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CV740 27hp bogs severely under average load

Sep 16, 2023#1

Turbodriven

Can anyone help here?

I'm absolutely baffled by this issue. I am now 100% out of ideas. The problem presents itself in two ways.

1. Within the first few moments of average load mowing, the motor RPMs dip significantly (about 5-10 seconds after engaging everything ). The greater the load, the more the RPMs dip. I hooked up at tachometer and it shows 1200 at low idle, 3600 "high idle", and during mowing it will usually sit right around 1700 RPMs depending on load (barely enough to mow). If it's a downhill, it'll go to 2500 or so, and small uphills dip to the point of basically being at low idle speed. If at any point I pull back the sticks to a stop (blades engaged), rpms will slowly pull back up to 3300+ RPMs (in 3-5 seconds). Push the stick forward and it dips back into the 1700 range.
2. Using clean plugs, cylinder #1 plug is always turns sooty black (carbon fouled) after a ten minute mow. Cylinder #2 is white to very light brown (varies). But never rich like #1.

I've put together a spreadsheet to track this problem. Just because after checking EVERYTHING I wanted to make sure I didn't miss anything. I know it's a lot, but it will show that I've tested all the typical problems.
The mower is a 2005 Gravely 260z (zero turn) that I bought a month ago for cheap.
I'm completely at my end here and would be happy for any experienced ideas.

Sep 16, 2023#2

M

mechanic mark

Kohler CV740 loses power under load

www.lawnsite.com

Found this information above, let us know, thanks Mark

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Locate your engine above & see Troubleshooting Section.

Sep 16, 2023#3

Turbodriven

mechanic mark said:
Kohler CV740 loses power under load

www.lawnsite.com

Found this information above, let us know, thanks Mark

Thank you for the idea. In his thread it appears as if he had the wrong flywheel which put him out of time. Although I'm certainly under the belief this feels like a timing issue, I don't think I have the wrong flywheel. When I upgraded to the MDI ignition system, I did a lot of research, and it comes in two flavors. One with just the coils and one with coils and a flywheel (to convert ASAM systems). I looked at my flywheel, and pictures of the one that comes in that full conversion kit, and they are the same (in regards to timing keyway positions at least). Also, in the the thread you posted, my flywheel looks like the corrected marks he used to fix the problem. Not like his original flywheel.

All that being said. Is it near impossible to skip a timing gear on these things? Without opening up the case I can't really check that.

Sep 16, 2023#4

V

VegetiveSteam

This first bit has nothing to do with your issue but a little extra info for others possibly looking at this thread for their own issues. There are actually three conversion kits for the Kohler Command twin variable timed ignition systems. There are two kits for converting ASAM ignitions that come with a flywheel and two ignition modules. One kit is for both 22 and 23 hp engines and the other is for 25 hp engines. The third kit is for converting DSAM or DSAI ignition systems to the current MDI system. You should have and probably did use kit # 25 707 03-S kit. So all that should be good.

When you checked the flywheel key did you remove the flywheel?

On a note about jumping time. Valve timing may or may not be your issue and It's not a very common problem but a Command twin can get out of valve time easier than you might think. Especially if the engine has ever been over heated. The gear on the crankshaft is a pressed on gear with no key. If the engine gets hot enough, the crankshaft gear can heat up and expand letting it become loose on the crankshaft causing the crankshaft to turn inside of it. The gear doesn't move. The crankshaft does. If you open up the engine, the timing marks will still be lined up because that relationship didn't change, but now if the crankshaft did turn inside the gear it will cause the pistons to be out of time with the valves. The only way to check if valve timing is off on a Command twin is to check valve overlap.

Sep 16, 2023#5

Turbodriven

VegetiveSteam said:
The only way to check if valve timing is off on a Command twin is to check valve overlap.

Can you elaborate... or point me to a source that references how to do this?

Sep 16, 2023#6

V

VegetiveSteam

Turbodriven said:
Can you elaborate... or point me to a source that references how to do this?

Sure. Can you answer me one question first please? Did you remove the flywheel to check the flywheel key?

Sep 16, 2023#7

Turbodriven

VegetiveSteam said:
Sure. Can you answer me one question first please? Did you remove the flywheel to check the flywheel key?

Oh sorry. Yes, I did. Checked the magnets too.

Sep 16, 2023#8

V

VegetiveSteam

Click on the link attached below. It will take you to another thread about no timing mark. Once there, go to post #10. I posted a process there. There is also a video attached there showing what valve overlap should look like.

A quick description would be, take both spark plugs out so you can turn the engine over by hand easily. Pick which ever side has the best access to be able to remove the rocker cover. Remove the rocker cover. Rotate the engine until you get the piston at top dead center exhaust stroke. Use wooden dowel that will fit into the spark plug hole so you can feel where the piston is. Just be sure it's long enough that it can't fall down inside the cylinder.

At this time in the cycle the exhaust stroke has just finished and the next stroke is the intake stroke. You will be right between those two strokes. At this point both valves should be open. They aren't open much but they should both be open. If you can rotate the flywheel back and forth about an inch or two clockwise then an inch or two counter clockwise you should see the rocker arms doing a teeter totter. That's valve over lap. If you get that situation of valve over lap with the piston at any other point in the cycle besides TDC exhaust stroke, the engine is out of valve time.

Kohler xt675-2047 NO MARK crankshaft

Hi everyone, I have a problem because when I was removing the oil pan, the camshaft in the Kohler xt675-2047 engine from the Viking lawn mower popped out. The worst thing about it all is that there is no mark on the gear that is mounted on the crankshaft (it is fixed in place, it is not...

www.lawnmowerforum.com

Sep 16, 2023#9

Turbodriven

OK, thanks. As it would happen, I currently have both rocker covers off right now. I'll check that in the morning and report back. To be honest thiugh, if this would be even just a little bit off I'd expect some sort of interference with the pistons. No?

Edit : I guess if it was off enough the piston would be heading back down the cylinder and no interference.

Sep 16, 2023#10

H

hlw49

Have you pulled the valve covers and checked the valve lift? Just pulling them and looking at the valves will not tell you anything you have to turn the engine over and watch the valves move. they should move about the same amount.

Sep 16, 2023#11

V

VegetiveSteam

Turbodriven said:
OK, thanks. As it would happen, I currently have both rocker covers off right now. I'll check that in the morning and report back. To be honest thiugh, if this would be even just a little bit off I'd expect some sort of interference with the pistons. No?

There is quite a bit of clearance. I don't think I've ever seen a valve on a Command twin get smacked by the piston.

Sep 16, 2023#12

Turbodriven

hlw49 said:
Have you pulled the valve covers and checked the valve lift? Just pulling them and looking at the valves will not tell you anything you have to turn the engine over and watch the valves move. they should move about the same amount.

Yep. Line 32 and 33 of my 'checklist'. All four valves open and close the same amount (+/-0. 2mm). Measured with a straight edge running over the valve cover mating surface on the head (as a baseline for each measurement).

Sep 16, 2023#13

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VegetiveSteam

Something I forgot to ask. Does the engine appear to run fine with no load? Any signs of fuel mist blowing back out of the carb?

Sep 17, 2023#14

Turbodriven

VegetiveSteam said:
Something I forgot to ask. Does the engine appear to run fine with no load? Any signs of fuel mist blowing back out of the carb?

Honesty, she starts easy, revs easy, and to my untrained ears sounds fine with no load. It sounds like every other lawn mower I've ever owned. Again, untrained ears. But I digress.

When I push the sticks forward after engaging the pto it's just like someone flips a switch and she falls on her face.

That said... after running I have pulled the intake hose right away and never noticed any fuel build up on any of the pipes. I haven't had my hand over the the intake while idling yet because frankly I wouldn't know what to feel for. But I'll pay attention for excessive fuel misting.

Sep 17, 2023#15

Turbodriven

Following up on the valve timing check. At TDC exhaust stroke (on both cylinders), the valves teeter right at exactly TDC. I'm going on a limb and saying it's not my issue.

The more I dig in, the more this motor is proving to me that it's healthy. Ugh. Is there any chance this is an external problem? It's not my spindles dragging for sure, I've checked those, but maybe my hyro's are pulling too much drag?? I don't know much about that system or how to check it. And then there is always the carbon fouled #1 thing. If it was an external drag pulling the motor back I'd think both cylinders would be affected? I'm about to set this whole thing on fire at this point.

Sep 17, 2023#16

V

VegetiveSteam

Turbodriven said:
Following up on the valve timing check. At TDC exhaust stroke (on both cylinders), the valves teeter right at exactly TDC. I'm going on a limb and saying it's not my issue.

The more I dig in, the more this motor is proving to me that it's healthy. Ugh. Is there any chance this is an external problem? It's not my spindles dragging for sure, I've checked those, but maybe my hyro's are pulling too much drag?? I don't know much about that system or how to check it. And then there is always the carbon fouled #1 thing. If it was an external drag pulling the motor back I'd think both cylinders would be affected? I'm about to set this whole thing on fire at this point.

Okay what do we know? Compression is good. Ignition and valve timing are good. Carb is good. Governor is working as it should as proven by your string. So that tells us that the engine is trying to provide more RPMs by going to wide open throttle but won't speed up. Too much external load is a possibility.

And just to verify, when you did the ignition update you used kit # 25 707 03-S. Correct?

Sep 17, 2023#17

Turbodriven

VegetiveSteam said:
Okay what do we know? Compression is good. Ignition and valve timing are good. Carb is good. Governor is working as it should as proven by your string. So that tells us that the engine is trying to provide more RPMs by going to wide open throttle but won't speed up. Too much external load is a possibility.

And just to verify, when you did the ignition update you used kit # 25 707 03-S. Correct?

Correct.

So the big question is how to test that hydro system? Or instead, what would cause a hydro system to have excessive load? If that's even possible? Fluid level is good and looks clean but it has a massive filter that I haven't changed. A clogged filter can't be an issue though, as it should have a bypass valve.

When I bought the mower it came with a 5 rib belt that was missing 2 ribs. So when I had the belt off to change it, I hand spun both hydro pumps and they felt fine (not overly stiff).

Another thing to note is that I'm pretty sure the parking brake is functioning correctly. I'm certain I checked this before but I'll release the hydro locks and make sure the mower rolls easy with the brake off to be sure.

Sep 17, 2023#18

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VegetiveSteam

I'm an engine guy so I'm no help with the hydros but were you able to look for any fuel mist blowing back out of the carb? And is the problem only with the blades engaged?

Sep 17, 2023#19

Turbodriven

VegetiveSteam said:
I'm an engine guy so I'm no help with the hydros but were you able to look for any fuel mist blowing back out of the carb? And is the problem only with the blades engaged?

No, valve covers are still off. I'm kind of tired of disassembling this thing and then putting it back together so I took a break today and cleaned up my gas leaf blower instead. I will though. And you're talking about just at high idle with the intake hoses off? What does that indicate if there is?

In regards to the second question. It feels like a combined load thing. The combined load of the blades and the hydros cause the issue.
So for example.
Sticks forward, blades engaged, I have a problem and shes at 1700rpms on flat ground.
Sticks at neutral (mower sitting still), blades engaged, and rpms go back to normal (3300+ rpms).
Sticks forward, blades disengaged and the rpms dip, but not as severe. It'll sit at 2500rpms instead of 1700 on flat ground for example.
The hydros are defininately pulling more average load than the triple blades given these behaviors, which may be completely normal? This is my first zero turn so I can't say.

Something to note, when I say "flat ground" I mean not going up hills. A lot of my property is on a mild slope which I mow sideways (think right or left wheel on the downhill). And I have noticed the problem is slightly less severe when I mow my front yard which is truly flat. As I understand, these Y intake CV Kohlers don't like operating sideways, with gravity and such. It's not my problem per se, but I'm sure it's not helping things.

Sep 17, 2023#20

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VegetiveSteam

I'm trying to figure out how to type this that it makes sense. What I am looking for is an exhaust restriction. I know your spreadsheet mentioned checking that but it may need to be looked at a little deeper. If there is restriction it builds up back pressure and can cause fuel to mist back out of the carb. With no load the engine can reach full RPMs with the throttle plate barely cracked off the idle stop. In that position there isn't a large amount of exhaust to try and get rid of so there may not be any mist blow back. You can try over speeding the engine momentarily 5 or 6 hundred RPMs by hand grabbing the governor lever and look for mist blow back. These engines will easily run over 4000 RPMs with no danger of harming the engine. They hydraulic lifters will begin to float if the RPMs get excessive and that will cause the engine to start cutting out and limit the RPMs. It's sort of an unintended benefit of hydraulic lifters on this engine that won't let it destroy itself from over speeding.

Depending on how the engine is mounted in the equipment it might be easier to just loosen the exhaust at the heads and see if that helps how it runs. It doesn't take much movement of the exhaust manifold away from the heads to notice a difference if there is a restriction in the exhaust.

Sep 18, 2023#21

Turbodriven

I've taken the exhaust off a few times now. It's not hard. It'll be loud but I'll try running it without to see what happens. Previously I blew through each exhaust port with (sealed) compressed air. #1 wasn't "holding pressure" different than #2 or anything but the testing method did seem pretty un-scientific at the time because my compressor wasn't filling that whole muffler in any quick order.

The more I think about it "scientifically", the more I think that it's the only thing that makes sense really though. Assuming a carbon fouled #1 isn't just some inherent design issue with this motor when you run it at low rpms under load for 5-10min (because the motor is being held back from some external issue).

If it's not a design issue, then we have to look at all the possible (generic) causes of carbon fouling on only 1 cylinder. It has to be one of three things. Too much fuel, too much oil, or not enough air. That's really all it could be.
1.We can eliminate too much fuel because the fuel/air atomizes at the single carb on this motor and gets put into both cylinders equally straight through the intake valves (both 1 and 2 intake valves were tested and they operate the same). If it was a too much fuel issue it would affect both cylinders.
2. It can't be oil because the leakdown test was passing, I'm not burning large amounts of oil, the head gaskets are new, and the valve seals were holding back gas (and therefore oil from the heads too) when I tested the valves. So there is nowhere for the oil to come from. Granted some oil is probably leaking past average condition rings, but not just on cylinder 1. That would be happening on both 1 and 2.
3. Literally the only thing (in my mind) that this could be, is that on the exhaust stroke, not all the un-burnt fuel on #1 is being allowed to exit. Creating a rich condition on the next intake stroke. And we know that the exhaust valve opens the same as #2 (again, checked cold). So this problem wouldn't be at the cylinder head given that evidence.

It's possible that when the motor gets hot the valves are acting differently for some reason. Or maybe the hydraulic lifters are not operating properly under load? It seemed to have fresh oil when I bought it so I didn't do an oil change. Perhaps I should. I know oil viscosity affects how hydraulic lifters perform (although I'm not an expert on hydraulic lifters either). That said, improper oil would affect all the lifters equally. So it sort of rules itself out.

Sorry for the long post, it's mostly me putting my thoughts on paper. I'll check the exhaust and report back. Thank you for all your help so far!

Sep 18, 2023#22

V

VegetiveSteam

I know you mentioned that all the valves were opening the same distance and sorry if I missed it but, how much are they moving? 3/8" or more?

And with a single barrel carb feeding two cylinders, one spark plug on a Command twin is typically just a slight bit darker than the other. The difference doesn't normally jump out at you but it is noticeable when you lay them side by side. So #1s being fouled is letting us know something is not right.

Sep 18, 2023#23

V

VegetiveSteam

Has it ever run right for you since you bought it?

Sep 18, 2023#24

Turbodriven

VegetiveSteam said:
Has it ever run right for you since you bought it?

No, I bought it about a month ago with a slew of problems. Mostly electrical issues which I sorted out. It was completely missing a starter relay for example. And wires were cut and/or not hooked up to the ignition switch (ad said it needed a new switch, but it did not)

But no, it always had this rich/motor bogging issue for me.

I bought it from an old guys son who didn't know anything about it. His dad came out for a few seconds at the end and just in passing mentioned that he parked it a year ago because of a leaking crank seal. He had maybe 10 mowers scattered around his lawn. Not one drop of oil has leaked past the crank seal on this since I owned it though. And he didn't seem superbly mechanical. So maybe he was confused about a different mower. Curious detail though.

I know you mentioned that all the valves were opening the same distance and sorry if I missed it but, how much are they moving? 3/8" or more?

It's tricky to get a measurement, but both intake valves are opening a total of 7mm. Exhaust appears to be the same.

Sep 18, 2023#25

Turbodriven

VegetiveSteam said:
I know you mentioned that all the valves were opening the same distance and sorry if I missed it but, how much are they moving? 3/8" or more?

I just took a look in the Kohler manual. It appears as if 7mm is a bit out of spec? Unless this needs to be done on a hot engine (hydro lifters freshly pumped up)? The motor has been cold and sitting for a few days.

Again though, #1 and #2 are the same amount out of spec. So it wouldn't explain why only #1 is rich??

Sep 18, 2023#26

V

VegetiveSteam

Retiring two years ago, I worked 27 years for a Kohler distributor doing this exact thing for about 9 months out of the year. We dealt mostly with Kohler authorized dealers helping them with engine troubleshooting, parts help and warranty. That was a little easier than this because it was all done on the telephone. A tech would call in and we’d discuss a few things to check or try. If they still had trouble they’d call back and we’d try to think of other things. Sometimes we found a solution with one call and sometimes it took multiple calls but we normally would find the issue.

The other 3 months of the year were spent conducting in person 4-day factory required schools for new Kohler dealers and update seminars for current Kohler dealers.

I also spent 14 years on the EETC 4-cycle test committee. While I feel I have a good bit of knowledge, mostly about Kohler engines, I admit not doing it everyday has dulled my skills some. Things that would just come right off the top of my head aren’t second nature any longer. I had a huge amount of reference material loaded with notes I’d made over the years. Thinking I wouldn’t have much need for it anymore I threw most of it away about a year ago. I threw away over 25 years of factory update books with notes in each one from our yearly factory training. I would love to that info back.

I think that as far as the engine goes you’ve covered just about everything there is to cover other than maybe a little more checking on possible exhaust restriction.

It reminds me of what my boss used to say when I’d ask him his opinion or to help me understand what I might be missing. He was a great guy and spent over 40 years teaching Kohler engines. He forgot more about Kohler K-series and Magnum engines than I ever knew. He was funny with a great sense of humor. I’d ask him for advice, and I’d say, we’ve, (meaning me and the technician), tried everything. He always like to reply, “you haven’t tried everything, or you would have found the problem.” I learned quickly to change my verbiage and started saying, “we’ve tried everything we can think of.

That leads me to the point of my rant. What are we missing? It was nice when I was still working. Three of us shared an office so it was easy to bounce ideas off each other. Usually someone would come up with something that might have been missed. If we were still lost, one of us would call the factory and run it past one of their techs.

I feel if the exhaust restriction turns up negative, it could be a hydro load issue but I just don't know. You’ll need to find someone smarter than me for testing that.

Once it's back together running again, if it's possible, post a video of it acting up. Maybe even one of it sitting running with no load at idle and also full throttle. Who knows. Maybe someone will hear something.

Sep 18, 2023#27

Turbodriven

VegetiveSteam said:
I feel if the exhaust restriction turns up negative, it could be a hydro load issue but I just don't know. You’ll need to find someone smarter than me for testing that.

Once it's back together running again, if it's possible, post a video of it acting up. Maybe even one of it sitting running with no load at idle and also full throttle. Who knows. Maybe someone will hear something.

If it's the exhaust, I'll throw a party I swear. Fingers crossed.

If not, I'll take a video. Or two. One of it starting cold and throttling up and down with no load. And one mowing showing the precise issue on the tach.

Sep 18, 2023#28

Turbodriven

Well, it's not the exhaust.
Interesting note, it runs like absolute dog sh@t without the muffler attached. Still dropping rpms though. With the added poor running, it was almost un-driveable now.

Also interesting, is the residue left from each cylinder. I took pics. The exhaust from the heads (muffler off) dumps onto the motor mount plate which is normally gloss black. Cylinder 1 is significantly blacker and spread wider. There is something going on in this engine.

At this point I just think this motor needs to be pulled apart piece by piece and inspected. Valves, crank case, everything. Whatever is causing this should be pretty obvious once I find it I would think. I'm out of external ideas though. Nothing from the outside is giving it away for sure.

I'll put the muffler back on tomorrow and shoot the two videos still. See if that presents any evidence I'm incapable of seeing.

Sep 18, 2023#29

V

VegetiveSteam

Maybe tearing into it is the next step but to me, the things you've checked such as, compression and valve timing on top of new head gaskets says to me it's not internal. But it wouldn't be the first time I was wrong. Your valves may be opening a bit under spec but I don't think it's enough to be an issue.

After you get it back together, try running it on one cylinder at a time and see if it runs the same on both sides. I know others will disagree and say they do it all the time with no issues but my recommendation, (actually Kohler's recommendation right in their service manual) is to not pull a plug wire while the engine is running or run the engine with a plug wire dangling firing to the atmosphere. Pull the plug lead and ground it to the block with a spark tester or some other way. Those leads need to be grounded. Then start the engine. Not doing it this way probably won't damage the ignition module immediately but there is a good chance if you pull the plug wire while running or let it fire ungrounded you've shortened the life of the ignition module.

Since there is normally no immediate failure people think it doesn't hurt anything. But when the customer returns in the next year or two needing a new ignition module, the tech who pulled the lead while running could be the reason they need it and it probably should have lasted a lifetime.

I didn't watch the video from an earlier post but I think you said you feel the flywheel is the correct flywheel? Not knowing the history or what the previous owner might have done to it doesn't help you any either. There's possibly more to it than they shared with you.

Sep 18, 2023#30

Turbodriven

VegetiveSteam said:
I didn't watch the video from an earlier post but I think you said you feel the flywheel is the correct flywheel? Not knowing the history or what the previous owner might have done to it doesn't help you any either. There's possibly more to it than they shared with you.

Yeah I'm almost certain it's correct. I base this on the following: the flywheel that comes with the 24-755-308-S MDI conversion kit has 8 gear teeth between the keyway and the start of the magnet. So does my flywheel. It's a little different in overall design but the timing degree is the same. And my flywheel was caked with grass/dirt on the internal magnets when I pulled it. Somone put hundreds of hours on it for sure prior to me owning it. I'm guessing hundreds of hours that the motor was healthy?

Sep 19, 2023#31

Turbodriven

VegetiveSteam said:
Once it's back together running again, if it's possible, post a video of it acting up. Maybe even one of it sitting running with no load at idle and also full throttle. Who knows. Maybe someone will hear something.

Ok here you are with the videos.

First video, cold starting and running.

Second video could use some narration as it's loud and bumpy (my yard isn't as smooth as I'd like) and I'm trying to drive a 2 stick zero turn with one hand in most of it.
1. First part is me running with blades engaged. You'll notice she falls on her face at about the 0:50 second mark a few seconds after moving. Make sure you full screen and have it the highest resolution so you can "pause" the video and maybe see the RPMs better at any given moment (youtube didn't upload at the full resolution for some reason). RPMs seem to hang mostly around 1500-1600 though and it dips down to 1200 when going up hills which is barely running.
2. Second part is driving with the blades disengaged. It hangs about 2500 and dips to about 1400 or so once after an uphill.
3. RPM's always come back up when I pull the sticks back though. And as you can see, the problem is at about 40% intensity with just the hydro drives engaged, and 100% with the drive and blades combined.

I'll take this moment to bring up two ideas.
#1 - a collapsed or locked hydraulic lifter? Would this manifest itself under load and cause the condition we have here? Or would this be apparent event while manually rotating the crank by hand (or running but sitting still).
#2 - heavily gummed up valves? On the back side of the valves. I've had the heads off previously and looked in the ports. I remember them being dirty, naturally, but not to the extreme. But this was just a cursory glance at best and my eyes haven't been calibrated in years. I didn't have the right valve removal tool so I never took the valves out.

Sep 19, 2023#32

Turbodriven

VegetiveSteam said:
After you get it back together, try running it on one cylinder at a time and see if it runs the same on both sides.

I did this and just grounded the unplugged boot with a alligator clip test lead. (note, I think these new MDI coils have built in protection though. As they have a lead running back from the boot and grounding out under a bolt of your choosing).

Neither side runs great by itself and neither would hold idle. The only noticeable difference between both sides is that when #1 was running, I was getting black sooty exhaust (noticeable). Whereas the #2 did not. I suppose this is to be expected. Edit: I realize though, that with black soot coming out of #1 under a no-load situation, it confirms that this is indeed a motor problem and not a loaded hydro (or other external) issue.

Sep 19, 2023#33

V

VegetiveSteam

I would agree. It's an engine issue but all the tests so far aren't revealing anything. A collapsed lifter should cause less rocker arm movement and be noticeable. They all move the same, so to me, that rules that out.

I'm going to bore you with a couple more questions. This is exactly how the engine ran when you got it correct? And after everything you've done it is unchanged? No better and no worse?

Sep 19, 2023#34

Turbodriven

VegetiveSteam said:
I would agree. It's an engine issue but all the tests so far aren't revealing anything. A collapsed lifter should cause less rocker arm movement and be noticeable. They all move the same, so to me, that rules that out.

I'm going to bore you with a couple more questions. This is exactly how the engine ran when you got it correct? And after everything you've done it is unchanged? No better and no worse?

Essentially yes. I would say that I feel like when I first got it I could still mow my lawn with a bit of a struggle. But now I feel like I'm a bit worse. Seat of my pants meter only. I could just be frustrated. None of the data has changed though. Still bogging about the same. Still getting carbon fouled on #1 only. Everything is the same except once in the beginning I ran compression with my crap Amazon tester and got like 170 instead of 160. Cylinders may have been wet though. I can't say. Which would have explained it.

Sep 19, 2023#35

V

VegetiveSteam

Turbodriven said:
Essentially yes. I would say that I feel like when I first got it I could still mow my lawn with a bit of a struggle. But now I feel like I'm a bit worse. Seat of my pants meter only. I could just be frustrated. None of the data has changed though. Still bogging about the same. Still getting carbon fouled on #1 only. Everything is the same except once in the beginning I ran compression with my crap Amazon tester and got like 170 instead of 160. Cylinders may have been wet though. I can't say. Which would have explained it.

Anything above 150 psi is good and your leak down test was good so the rings and cylinders seem good. I know there is the issue with some smoking on #1 cylinder but whatever is wrong seems to be affecting both cylinders.

It sounded really good when you started it cold even at idle. I know the flywheel key was checked and you had correct overlap with all valves open at TDC exhaust but to me it still acts like it's slightly out of time.

You did say that the valves were moving slightly less than spec so pulling the engine and inspecting the cam might be the next step. This may sound like an odd question but have you noticed anyplace on the equipment that looks like it's been welded on with an arc welder?

Sep 19, 2023#36

Turbodriven

VegetiveSteam said:
This may sound like an odd question but have you noticed anyplace on the equipment that looks like it's been welded on with an arc welder?

Nope. I haven't done a full inspection but I got a pretty good look at the heads when they were off and a decent look at the cylinder sections.

That said, it wouldn't surprise me if this thing got a bit hot in it's 1200hr life. I'm in Florida so we're in a pretty warm climate and the fins were a bit caked up when I got in there. Heads were flat though (not perfect but well under 'max out of spec' ).

If something was cracked or out of shape in some way I have to assume it's going to be a pretty obvious defect given such a severe lack of power it'd be causing.

I'm going to start pulling the motor out of the mower and tearing it down. I think we're at that point unfortunately.

Thank you for your help. I'll keep you posted.

Sep 21, 2023#37

Turbodriven

Ok, so I really don't know what I should do at this point. To be honest, I don't see anything glaringly wrong anywhere inside this motor. No cracks or case defects. Cam lobes all measure the same, governor gear assembly looks good. Crank seals are tired but they weren't leaking (I'm going to replace anyways). Oil passages look clear. And the valves don't look overly gummed up (just a small amount of carbon buildup which is normal I think).

So, I know that my rings aren't perfect (acceptable but not perfect). But I'm feeling like I should do a ring job while I'm in here. I haven't pulled the pistons yet but I do want to check the current rings too in order to see how they look. Make sure none are seized or anything. Cylinders look glazed but 100% smooth. I can still see cross hatching in the metal walls. A quick hone and fresh rings wouldn't hurt if I plan to put more years on her. And rings are fairly cheap.

The bigger question is the cam. We know my valves were opening 7mm instead of the manual recommended 8mm. But all my cams lobes measure the same (34.5mm). A new cam is $170 plus I've read scare tactic posts that you have to replace your hydraulic lifters too. And then break them in with 20 minutes at 2000rpms or the cams will be toast within an hour. Putting new cams in is another $80+. Probably a realistic $300 total parts list after tax. Unless I just throw a good used cam in for significantly cheaper. But I've heard that's just throwing money down the drain as you'll likely only get 30min in before the lobes wear down to round using old (mismatched) lifters. Scare tactics?

I know you have some experience with these engines. I'd love to hear your opinions on this. In the bigger picture too, and to the point of this thread, I've got this gut feeling that these cams aren't my problem. *shrug

Sep 21, 2023#38

S

slomo

What I hear with headphones on, from your video OP, is normal RPM's in the first video. Low idle is lower than you will ever use and high sounded fine to me.

Your next video, sounded like, you have one or several bad bearings in the deck. Sounded awful mechanical when you engaged the blades. Heard a lack of engine rpm with the blades on. Like you have some aftermarket blades or some high lift wonder blades of the week on her. Are you running OEM blades?

Summation the engine sounded fine until you loaded her up. I would be looking into the deck then the engine if it was me. Or your Chinese tachometer is not reading proper rpm's.

Sep 21, 2023#39

V

VegetiveSteam

Turbodriven said:
Ok, so I really don't know what I should do at this point. To be honest, I don't see anything glaringly wrong anywhere inside this motor. No cracks or case defects. Cam lobes all measure the same, governor gear assembly looks good. Crank seals are tired but they weren't leaking (I'm going to replace anyways). Oil passages look clear. And the valves don't look overly gummed up (just a small amount of carbon buildup which is normal I think).

So, I know that my rings aren't perfect (acceptable but not perfect). But I'm feeling like I should do a ring job while I'm in here. I haven't pulled the pistons yet but I do want to check the current rings too in order to see how they look. Make sure none are seized or anything. Cylinders look glazed but 100% smooth. I can still see cross hatching in the metal walls. A quick hone and fresh rings wouldn't hurt if I plan to put more years on her. And rings are fairly cheap.

The bigger question is the cam. We know my valves were opening 7mm instead of the manual recommended 8mm. But all my cams lobes measure the same (34.5mm). A new cam is $170 plus I've read scare tactic posts that you have to replace your hydraulic lifters too. And then break them in with 20 minutes at 2000rpms or the cams will be toast within an hour. Putting new cams in is another $80+. Probably a realistic $300 total parts list after tax. Unless I just throw a good used cam in for significantly cheaper. But I've heard that's just throwing money down the drain as you'll likely only get 30min in before the lobes wear down to round using old (mismatched) lifters. Scare tactics?

I know you have some experience with these engines. I'd love to hear your opinions on this. In the bigger picture too, and to the point of this thread, I've got this gut feeling that these cams aren't my problem. *shrug

How do the lifters look? Can you post a pic of the side that runs on the cam? And you don't want to change the cam if it's not needed obviously, but for a different reason than you may think.

Kohler says to replace the camshaft and crankshaft together. Never just replace one. So you'd be looking at a cam, crank and new lifters. The reason is, the teeth on the crank gear and the cam gear create a wear pattern on each other over hours of running. If you were to replace just the cam and lifters, and not the crankshaft, at best the engine will probably have a knock. It sounds very similar to a rod knock. I've hear it several times. At worst, the uneven pressure being put on the crank gear now with new cam teeth running against worn crank teeth can cause the crank gear to crack letting the crankshaft turn inside of it causing valve timing to be off. I've also seen that a number of times. The same result we discussed previously with an overheated engine and valve overlap.

The good thing is you probably don't need a new camshaft so none of what I just typed will probably matter.

If everything inside looks good, and there is no odd wear on the cam side of the lifters, I would take them apart and clean them. Then reassemble them with just a drop or two of oil. With the lifter sitting if front of you, you should be able to take a push rod and push in the lifter plunger. The plunger should spring back when you release the push rod pressure. Then put them back in the engine coated with oil on the outside but just the drop or two inside. You want them pretty much empty. They will clatter when you start the engine but will quiet down in just a few seconds.

I'm going to read back over some of what you posted to see what other ideas might come to mind.

Sep 21, 2023#40

V

VegetiveSteam

While you have it apart, look at the crankshaft gear very closely for anything resembling a crack.

Sep 21, 2023#41

Turbodriven

slomo said:
What I hear with headphones on, from your video OP, is normal RPM's in the first video. Low idle is lower than you will ever use and high sounded fine to me.

Your next video, sounded like, you have one or several bad bearings in the deck. Sounded awful mechanical when you engaged the blades. Heard a lack of engine rpm with the blades on. Like you have some aftermarket blades or some high lift wonder blades of the week on her. Are you running OEM blades?

Summation the engine sounded fine until you loaded her up. I would be looking into the deck then the engine if it was me. Or your Chinese tachometer is not reading proper rpm's. All this valve and such talk is getting you no place fast.

I currently have the belt off so I could take a video of the spindles spinning by hand. They don't sound gritty to me like bad bearings would. I'll check again though with some side tension applied. And I'll take a pic of the blades but I did sharpen them. No idea what they are though.

It's also important to note that I'm getting a slight power loss even without blades engaged. I'm at about 2500 rpms on flat ground just driving around. I haven't focused on blades/spindles because of this.

Sep 21, 2023#42

S

slomo

Turbodriven said:
It's also important to note that I'm getting a slight power loss even without blades engaged. I'm at about 2500 rpms on flat ground just driving around.

Have you checked the weight of that mega mower with YOU on it? Talking thousands of pounds guy. So you have this issue without the deck on. Okay that "could" rule out the deck. What is next? Something hydro related dogging the engine down? Is your mower hydro driven or a belt? Rule these out then look back into the engine.

Sep 21, 2023#43

Turbodriven

VegetiveSteam said:
While you have it apart, look at the crankshaft gear very closely for anything resembling a crack.

I'm in the office today, I'll look when I get home. Are you implying that a crack could allow the gear to slip? I thought we ruled that out when we verified exhaust tdc to be correct?

Sep 21, 2023#44

Turbodriven

slomo said:
Have you checked the weight of that mega mower with YOU on it? Talking thousands of pounds guy. So you have this issue without the deck on. Okay that "could" rule out the deck. What is next? Something hydro related dogging the engine down? Is your mower hydro driven or a belt? Rule these out then look back into the engine.

It's belt driven hydros. I've definitely considered malfunctioning hydros externally putting too much load on the motor, but that doesn't explain my carbon fouled cyl #1 (only). And this thing should normally run at 3300rpms under normal loads. I only weigh 175lbs

. Back to the blades.. When I'm sitting with the blades engaged my rpms actually go up. It's in the second video. When I pull back the sticks the rpms come back up to 3300 rpms (blades still engaged). That said, when I first engage the blades in the beginning of the second video, the engine first struggles, then climbs back up to 3300. This is all pointing to the engine in my opinion. Whenever a load is applied (no matter what it is) the engine struggles.

Sep 21, 2023#45

V

VegetiveSteam

Turbodriven said:
I'm in the office today, I'll look when I get home. Are you implying that a crack could allow the gear to slip? I thought we ruled that out when we verified exhaust tdc to be correct.

Yes. A crack would allow the gear to slip and yes that should have been ruled out by checking overlap, but since you're in there I figured it couldn't hurt to take a look.

And if you could clarify something for me. When you ran the engine on one cylinder at a time you said neither side would hold idle. I'm not quite sure what you meant. Was this with no load the engine wouldn't idle running on just one cylinder?

Sep 21, 2023#46

Turbodriven

VegetiveSteam said:
And if you could clarify something for me. When you ran the engine on one cylinder at a time you said neither side would hold idle. I'm not quite sure what you meant. Was this with no load the engine wouldn't idle running on just one cylinder?

Yes. I should have taken a video. When I unplugged either side, it was difficult to start. With both cylinders it's usually it's a pretty easy crank or two even at low idle throttle position, but with one side unplugged it struggled to start. A little 50-75% throttle feathering and she would though.

During normal operation with both sides running I can throttle all the way back to the stop and she'll easily hold 1150-1200 rpms (you saw the video). However when one side was unplugged, that action would kill the motor. To keep her running on one cylinder I would have to be at about 40% throttle (if I remember correct) and it was lumpy.

This was consistent of both sides. Neither idled well or started easy. The only difference I noticed between the two was that while running with #1 plugged in, I saw a noticeable sooty colored exhaust coming out. I don't normally see this with both running and not with just #2 running either.

Sep 21, 2023#47

Turbodriven

How do the lifters look? Can you post a pic of the side that runs on the cam?

See the pic. It's hard to get a good one as the mating surface of the lifters are almost chrome and it reflects my led shop lights.

On this subject, in your experience are these Kohler lifters the exact same as GM/Chevy small block lifters? I've heard they're the same (and they look the same) but Kohler charges 2x+ for theirs. LOL. Reminds me of a real world story where $200 Lamborghini side markers are literally off a Ford Fiesta or something and cost $20 at the Ford dealership.

Kohler says to replace the camshaft and crankshaft together. Never just replace one. So you'd be looking at a cam, crank and new lifters.

If I didn't hate Kohler engines before... I do now. This is just bad.

Sep 21, 2023#48

V

VegetiveSteam

Turbodriven said:
See the pic. It's hard to get a good one as the mating surface of the lifters are almost chrome and it reflects my led shop lights.
On this subject, in your experience are these Kohler lifters the exact same as GM/Chevy small block lifters? I've heard they're the same (and they look the same) but Kohler charges 2x+ for theirs. LOL. Reminds me of a real world story where $200 Lamborghini side markers are literally off a Ford Fiesta or something and cost $20 at the Ford dealership.

If I didn't hate Kohler engines before... I do now. This is just bad.

From what I see in the pics the cam lobes and lifters look fine.

As far as the lifters being the same as a small block GM, they are the same external size but according to Kohler they oil hole sizes are different. I can't say if GM lifters will work or not. I've never tried. They might work just fine.

Sep 21, 2023#49

Turbodriven

VegetiveSteam said:
From what I see in the pics the cam lobes and lifters look fine.

As far as the lifters being the same as a small block GM, they are the same external size but according to Kohler they oil hole sizes are different. I can't say if GM lifters will work or not. I've never tried. They might work just fine.

Yeah, and although I'm sure they're not perfect, as mentioned before... I don't think this is my problem. So with that being so, I'm not willing to drop $500 on a new crank/cam/and lifters for sure.

I'll bleed the lifters like you mentioned, hone and ring job the cylinders (need to make sure I order the right rings), and then slap this bottom end back together per the manual. I still have to pull my valves out of the head too and clean them up. Although they don't look super bad through the ports, I still want to check the guides and everything so I can say I touched everything.

Thanks for your wisdom.

Sep 21, 2023#50

V

VegetiveSteam

Let me ask a silly and probably useless question but, do you still have the spark advance module you took off this engine? If so, what's the number on it?

Sep 22, 2023#51

Turbodriven

VegetiveSteam said:
Let me ask a silly and probably useless question but, do you still have the spark advance module you took off this engine? If so, what's the number on it?

We talked about it in a different thread. I had the DSAM system apparently. The box was 24 584 27 and the coils were 24 584 15. I assume now they were all working fine?

Sep 22, 2023#52

Turbodriven

I was in the shop this morning and took a better look at my lifters (and got a better pic). They are all perfectly smooth except #1 intake (top left in pic1 with matching cam lobe the one nearest to it). You can feel that wear on the lifter with your finger.
A. would you be concerned about this? and..
B. if so, can I replace a just a single lifter or are we talking a full $500 crank/cam/lifter deal again? In your opinion?

Sep 22, 2023#53

V

VegetiveSteam

Turbodriven said:
We talked about it in a different thread. I had the DSAM system apparently. The box was 24 584 27 and the coils were 24 584 15. I assume now they were all working fine

And I know we talked about the flywheel too but since you're dealing with something elusive I thought it wouldn't hurt to know for sure you had DSAM. And you did. I'm trying to look under every stone.

Sep 22, 2023#54

V

VegetiveSteam

Turbodriven said:
I was in the shop this morning and took a better look at my lifters (and got a better pic). They are all perfectly smooth except #1 intake (top left in pic1 with matching cam lobe the one nearest to it). You can feel that wear on the lifter with your finger.
A. would you be concerned about this? and..
B. if so, can I replace a just a single lifter or are we talking a full $500 crank/cam/lifter deal again? In your opinion?

You can replace just one lifter. They used to come with a little tube of grease to put on the cam side. I assume they still do. Put a couple of drops of oil on the push rod socket side and a drop in the hole. Then run the engine at 1500 RPMs for 5 minutes.
The lifters normally rotate but not always. That straight line wear isn't all that uncommon and normally doesn't cause an issue.

Sep 22, 2023#55

Lawnman23

VegetiveSteam said:
The lifters normally rotate but not always. That straight line wear isn't all that uncommon and normally doesn't cause an issue.

What would cause that much of a grove on just the one intake lifter and nothing on the others? Usually its a lifter eating a cam lobe not visa-versa no?

Sep 23, 2023#56

G

gregjo1948

Turbodriven said:
Can anyone help here?

I'm absolutely baffled by this issue. I am now 100% out of ideas. The problem presents itself in two ways.

1. Within the first few moments of average load mowing, the motor RPMs dip significantly (about 5-10 seconds after engaging everything ). The greater the load, the more the RPMs dip. I hooked up at tachometer and it shows 1200 at low idle, 3600 "high idle", and during mowing it will usually sit right around 1700 RPMs depending on load (barely enough to mow). If it's a downhill, it'll go to 2500 or so, and small uphills dip to the point of basically being at low idle speed. If at any point I pull back the sticks to a stop (blades engaged), rpms will slowly pull back up to 3300+ RPMs (in 3-5 seconds). Push the stick forward and it dips back into the 1700 range.
2. Using clean plugs, cylinder #1 plug is always turns sooty black (carbon fouled) after a ten minute mow. Cylinder #2 is white to very light brown (varies). But never rich like #1.

I've put together a spreadsheet to track this problem. Just because after checking EVERYTHING I wanted to make sure I didn't miss anything. I know it's a lot, but it will show that I've tested all the typical problems.
The mower is a 2005 Gravely 260z (zero turn) that I bought a month ago for cheap.
I'm completely at my end here and would be happy for any experienced ideas.

View attachment 66771

Check a shop manual for proper valve adjustment. I think valves aren't supposed to be tdc when adjusted. I think there is a compression relief that holds the exhaust valve open a bit.

Sep 23, 2023#57

S

STEVES

worn valve guide/seal sucking oil / should of removed valves with head off, usually can do by hand pushing spring down /

Sep 23, 2023#58

J

JAZ

Turbodriven said:
Can anyone help here?

I'm absolutely baffled by this issue. I am now 100% out of ideas. The problem presents itself in two ways.

1. Within the first few moments of average load mowing, the motor RPMs dip significantly (about 5-10 seconds after engaging everything ). The greater the load, the more the RPMs dip. I hooked up at tachometer and it shows 1200 at low idle, 3600 "high idle", and during mowing it will usually sit right around 1700 RPMs depending on load (barely enough to mow). If it's a downhill, it'll go to 2500 or so, and small uphills dip to the point of basically being at low idle speed. If at any point I pull back the sticks to a stop (blades engaged), rpms will slowly pull back up to 3300+ RPMs (in 3-5 seconds). Push the stick forward and it dips back into the 1700 range.
2. Using clean plugs, cylinder #1 plug is always turns sooty black (carbon fouled) after a ten minute mow. Cylinder #2 is white to very light brown (varies). But never rich like #1.

I've put together a spreadsheet to track this problem. Just because after checking EVERYTHING I wanted to make sure I didn't miss anything. I know it's a lot, but it will show that I've tested all the typical problems.
The mower is a 2005 Gravely 260z (zero turn) that I bought a month ago for cheap.
I'm completely at my end here and would be happy for any experienced ideas.

View attachment 66771

Don't really think I will be of much if any help, but my Troy built 42 " did the same. Number 40 on your list said belts new or good. I replaced the belt on it and seems to have corrected the problem. Belt was good but stretched.

Sep 23, 2023#59

S

STEVES

if belts, are they on the correct side of guide?

Sep 23, 2023#60

Turbodriven

STEVES said:
worn valve guide/seal sucking oil / should of removed valves with head off, usually can do by hand pushing spring down /

Line 30 and 31 of my OP checklist sort of verified that at least the intake seal isn't leaking (and this motor has no seal on the exhaust valve by design). But I removed the #1 valves yesterday and they don't seem loose in the guides. Not tight, but not loose either. Guides are positioned vertically in the heads correctly too and haven't slipped. And leak down confirms that the exhaust valve is closing properly.

At this point I just think my motor is possessed by a demon. Nothing but a slightly out of spec cam is the only thing I see even remotely 'wrong'.

Sep 23, 2023#61

Turbodriven

gregjo1948 said:
Check a shop manual for proper valve adjustment. I think valves aren't supposed to be tdc when adjusted. I think there is a compression relief that holds the exhaust valve open a bit.

This motor has no compression release. And hydraulic lifters with no valve adjustment.

Sep 23, 2023#62

D

donslawns

Turbodriven said:
Can anyone help here?

I'm absolutely baffled by this issue. I am now 100% out of ideas. The problem presents itself in two ways.

1. Within the first few moments of average load mowing, the motor RPMs dip significantly (about 5-10 seconds after engaging everything ). The greater the load, the more the RPMs dip. I hooked up at tachometer and it shows 1200 at low idle, 3600 "high idle", and during mowing it will usually sit right around 1700 RPMs depending on load (barely enough to mow). If it's a downhill, it'll go to 2500 or so, and small uphills dip to the point of basically being at low idle speed. If at any point I pull back the sticks to a stop (blades engaged), rpms will slowly pull back up to 3300+ RPMs (in 3-5 seconds). Push the stick forward and it dips back into the 1700 range.
2. Using clean plugs, cylinder #1 plug is always turns sooty black (carbon fouled) after a ten minute mow. Cylinder #2 is white to very light brown (varies). But never rich like #1.

I've put together a spreadsheet to track this problem. Just because after checking EVERYTHING I wanted to make sure I didn't miss anything. I know it's a lot, but it will show that I've tested all the typical problems.
The mower is a 2005 Gravely 260z (zero turn) that I bought a month ago for cheap.
I'm completely at my end here and would be happy for any experienced ideas.

View attachment 66771

90% of the time when someone brings a mower in and they say that they have low power, they are running on one cylinder and don't know it because the exhaust doesn't sound that much different to the average person. Pull one spark plug wire off at a time. The engine should run on one cylinder and if you kill the engine by removing a plug wire then you know that the other cylinder is not producing power. You can also use an infrared to see if both exhaust pipes are hot, a cold pipe is a dead cylinder. If a dead cylinder is the problem you can work from there.

Sep 23, 2023#63

D

donens2018

From working with the Command series twins, my experience is that of faulty magnetos (coils). Also since Kohler used so many versions of coils, makes it difficult. The latest coils offered by Kohlers states to replace as a pair, primarily to avoid mixing up different versions. Sounds like you have coils failing. You may also check the kill wire, as Kohler for one version had a diode wired into the harness due to back feed. The newest coils have the diode built into the module.
Have you run engine with inline spark testers on each coil. Check for cylinder spark differences especially when it starts loosing power. Also check the wiring harness. I'm seen too many wiring harnesses with evidence of mice chewing. They like the insulation.

Sep 23, 2023#64

C

corvette 1

Turbodriven said:
Can anyone help here?

I'm absolutely baffled by this issue. I am now 100% out of ideas. The problem presents itself in two ways.

1. Within the first few moments of average load mowing, the motor RPMs dip significantly (about 5-10 seconds after engaging everything ). The greater the load, the more the RPMs dip. I hooked up at tachometer and it shows 1200 at low idle, 3600 "high idle", and during mowing it will usually sit right around 1700 RPMs depending on load (barely enough to mow). If it's a downhill, it'll go to 2500 or so, and small uphills dip to the point of basically being at low idle speed. If at any point I pull back the sticks to a stop (blades engaged), rpms will slowly pull back up to 3300+ RPMs (in 3-5 seconds). Push the stick forward and it dips back into the 1700 range.
2. Using clean plugs, cylinder #1 plug is always turns sooty black (carbon fouled) after a ten minute mow. Cylinder #2 is white to very light brown (varies). But never rich like #1.

I've put together a spreadsheet to track this problem. Just because after checking EVERYTHING I wanted to make sure I didn't miss anything. I know it's a lot, but it will show that I've tested all the typical problems.
The mower is a 2005 Gravely 260z (zero turn) that I bought a month ago for cheap.
I'm completely at my end here and would be happy for any experienced ideas.

View attachment 66771

New air cleaner, carb cleaner & spark plug.

Sep 23, 2023#65

M

moseemo54

Turbodriven said:
This motor has no compression release. And hydraulic lifters with no valve adjustment.

Had similar symptoms with my exmark Kohler, I believe it's a CH 745. Seemed like it was starving for fuel. Finally noticed the original fuel line on the suction side of the fuel pump was partially collapsing under load and restricting the flow. I had an experienced professional mechanic trouble shooting it with me and before we found it, had replaced the fuel filter and fuel pump. Might be something worth checking.

Sep 23, 2023#66

C

Cajun power

leak down test...start there.

and listen closely ..it could be from multiple places (head gasket failure, cracked or warped head, valves). this will establish and point you to where leaks might be coming from if you have leaks. (see youtube for numerous methods and standard tips. always do this on top dead center, one cylinder at a time)

also look for any blown gaskets in the intake manifold where it mates to the cylinder head. usually this will cause a very lean condition, but if the intake gaskets are big time blown, this messes up the fuel air mix and can cause alsoloss of power....but it's usually a very high revving engine and super hot even at idle! if the intake manifolds are warped, and or the gaskets have failed big time, then you simply don't get enough fuel or air..

also...make sure you don't have something wrapped around the blades, blade spindles, tensioner pulley, and or pto clutch. check those belts and make sure nothing is binding up the blades. (engine OFF when checking of course!)

is the fuel pump operating normally? (ENGINE OFF: remove the fuel line from the carb and crank the engine and let it run...make sure you have a catch can for gas and in a safe position...and a fire extinguisher at the ready just in case....fuel flow from fuel pump should be strong and steady.

when was the last time that the carb has been cleaned? specifically the main jet...at idle debris will allow the engine to run and sound normal...at a higher rpm fuel demand, debris in the carb can cause loss of power.

Sep 23, 2023#67

doug9694

Turbodriven said:
Can anyone help here?

I'm absolutely baffled by this issue. I am now 100% out of ideas. The problem presents itself in two ways.

1. Within the first few moments of average load mowing, the motor RPMs dip significantly (about 5-10 seconds after engaging everything ). The greater the load, the more the RPMs dip. I hooked up at tachometer and it shows 1200 at low idle, 3600 "high idle", and during mowing it will usually sit right around 1700 RPMs depending on load (barely enough to mow). If it's a downhill, it'll go to 2500 or so, and small uphills dip to the point of basically being at low idle speed. If at any point I pull back the sticks to a stop (blades engaged), rpms will slowly pull back up to 3300+ RPMs (in 3-5 seconds). Push the stick forward and it dips back into the 1700 range.
2. Using clean plugs, cylinder #1 plug is always turns sooty black (carbon fouled) after a ten minute mow. Cylinder #2 is white to very light brown (varies). But never rich like #1.

I've put together a spreadsheet to track this problem. Just because after checking EVERYTHING I wanted to make sure I didn't miss anything. I know it's a lot, but it will show that I've tested all the typical problems.
The mower is a 2005 Gravely 260z (zero turn) that I bought a month ago for cheap.
I'm completely at my end here and would be happy for any experienced ideas.

View attachment 66771

Sep 23, 2023#68

R

riceski@gmail.com

Turbodriven said:
Can anyone help here?

I'm absolutely baffled by this issue. I am now 100% out of ideas. The problem presents itself in two ways.

1. Within the first few moments of average load mowing, the motor RPMs dip significantly (about 5-10 seconds after engaging everything ). The greater the load, the more the RPMs dip. I hooked up at tachometer and it shows 1200 at low idle, 3600 "high idle", and during mowing it will usually sit right around 1700 RPMs depending on load (barely enough to mow). If it's a downhill, it'll go to 2500 or so, and small uphills dip to the point of basically being at low idle speed. If at any point I pull back the sticks to a stop (blades engaged), rpms will slowly pull back up to 3300+ RPMs (in 3-5 seconds). Push the stick forward and it dips back into the 1700 range.
2. Using clean plugs, cylinder #1 plug is always turns sooty black (carbon fouled) after a ten minute mow. Cylinder #2 is white to very light brown (varies). But never rich like #1.

I've put together a spreadsheet to track this problem. Just because after checking EVERYTHING I wanted to make sure I didn't miss anything. I know it's a lot, but it will show that I've tested all the typical problems.
The mower is a 2005 Gravely 260z (zero turn) that I bought a month ago for cheap.
I'm completely at my end here and would be happy for any experienced ideas.

View attachment 66771

Try this and I have found this to be an absolute -- charge the battery to the fullest - or even put a different good battery in the mower - have found IF the battery doesn't deliver enough amperage it can cause what you are saying to happen. If the alternator isn't putting out enough to run everything correctly - these symptoms can come about. Good luck with it.

Sep 23, 2023#69

doug9694

The only thing I can come up with is maybe a leaky porous casting around the intake valve or the intake manifold itself.
Carefully see if one cylinder is running much cooler then the other. Or use an infrared thermometer.
The cool cylinder is most likely where the issue is.
Reading more comments another prob. may be a hydraulic lifter collapsed after the cold thick oil thins when warm.
Also do the spark plug wire pull test. That should tell which is bad.

Sep 23, 2023#70

S

Sockmonkey

Turbodriven said:
Can anyone help here?

I'm absolutely baffled by this issue. I am now 100% out of ideas. The problem presents itself in two ways.

1. Within the first few moments of average load mowing, the motor RPMs dip significantly (about 5-10 seconds after engaging everything ). The greater the load, the more the RPMs dip. I hooked up at tachometer and it shows 1200 at low idle, 3600 "high idle", and during mowing it will usually sit right around 1700 RPMs depending on load (barely enough to mow). If it's a downhill, it'll go to 2500 or so, and small uphills dip to the point of basically being at low idle speed. If at any point I pull back the sticks to a stop (blades engaged), rpms will slowly pull back up to 3300+ RPMs (in 3-5 seconds). Push the stick forward and it dips back into the 1700 range.
2. Using clean plugs, cylinder #1 plug is always turns sooty black (carbon fouled) after a ten minute mow. Cylinder #2 is white to very light brown (varies). But never rich like #1.

I've put together a spreadsheet to track this problem. Just because after checking EVERYTHING I wanted to make sure I didn't miss anything. I know it's a lot, but it will show that I've tested all the typical problems.
The mower is a 2005 Gravely 260z (zero turn) that I bought a month ago for cheap.
I'm completely at my end here and would be happy for any experienced ideas.

View attachment 66771

Sep 23, 2023#71

S

Sockmonkey

Check the governor linkage/settings.

Sep 23, 2023#72

S

STEVES

do both intake valves have the same 'deposit' on the stem?

Sep 23, 2023#73

L

LMPPLUS

Sounds like you have a compromised head gasket.

Sep 23, 2023#74

B

biggertv

Sounds like a Fuel/Air Delivery problem.

Sep 23, 2023#75

C

CWatters

I know you suction tested the fuel feed and changed the filter but twice now I've had insects cause my mower to bog down under load. In both cases I disconnected the fuel line after the filter and because fuel drained out I assumed it was all OK. In one case it would run for an hour and cut 1.5 acres before bogging down! I would drain your fuel tank and dry the inside with rags. Vacuum out any debris. In one case the insects partially blocked my fuel switch which on my mower is before the filter. So my filter looked OK, some fuel drained out but the line was still blocked just enough to be an issue under load. Idle and unloaded it ran fine.

If not already checked I would also remove the deck belt and turn the blades by hand to check they aren't partly binding.

Compression check both cylinders.

Sep 23, 2023#76

OzPete

Worn valve lifters will give that symptom. They are Hydraulic Lifters, and they wear out.
We had a similar issue on a CH740 in a Walker. Replacing all four Hydraulic Lifters resolved it straight up.

Sep 23, 2023#77

doug9694

OzPete said:
Worn valve lifters will give that symptom. They are Hydraulic Lifters, and they wear out.
We had a similar issue on a CH740 in a Walker. Replacing all four Hydraulic Lifters resolved it straight up.

I agree!

Sep 23, 2023#78

T

TobyU

Turbodriven said:
Can anyone help here?

I'm absolutely baffled by this issue. I am now 100% out of ideas. The problem presents itself in two ways.

1. Within the first few moments of average load mowing, the motor RPMs dip significantly (about 5-10 seconds after engaging everything ). The greater the load, the more the RPMs dip. I hooked up at tachometer and it shows 1200 at low idle, 3600 "high idle", and during mowing it will usually sit right around 1700 RPMs depending on load (barely enough to mow). If it's a downhill, it'll go to 2500 or so, and small uphills dip to the point of basically being at low idle speed. If at any point I pull back the sticks to a stop (blades engaged), rpms will slowly pull back up to 3300+ RPMs (in 3-5 seconds). Push the stick forward and it dips back into the 1700 range.
2. Using clean plugs, cylinder #1 plug is always turns sooty black (carbon fouled) after a ten minute mow. Cylinder #2 is white to very light brown (varies). But never rich like #1.

I've put together a spreadsheet to track this problem. Just because after checking EVERYTHING I wanted to make sure I didn't miss anything. I know it's a lot, but it will show that I've tested all the typical problems.
The mower is a 2005 Gravely 260z (zero turn) that I bought a month ago for cheap.
I'm completely at my end here and would be happy for any experienced ideas.

View attachment 66771

One thing that caught my attention in your other post was that you said when it's running with no load it's about $3,600 RPMs which I feel is a little bit high but not terrible. Most of these mowers are designed to run no more than 3,400 today but again, I forget what it's actually on and I think it was a larger gravely but don't remember if it was commercial residential but regardless 3600 is not terribly fast.
But when you said you engaged the blaze in it bogs down and then comes back up that is a classic sign of one of two things...

Either the engine power is low and it's weak for whatever reason or the governor is crazy out of adjustment or not working at all and not allowing the carb to do its job.

I I find the quickest diagnosis for this is to actually watch the carburetor throttle plate from the top and to first verify that it can open all the way and then when you pull the blades on watch to see if the carburetor throttle plate is opening all the way during that entire time that it's bogging down and coming back up too freewheeling speed.
I have seen more than one engine that sounded like it was lawn power etc when in fact it was just a governor adjustment.
Other times, the governor has been busted and they have basically adjusted the throttle so it will go no faster than somewhere around 3,600 RPMs and of course it will bog when you put a load on it because the throttle cannot move on its own.

Sep 24, 2023#79

S

Savage3

Try spraying carb cleaner around intake where carb mounts. If RPM changes, there is an air leak.

Sounds like two possibilities worth investigating:

1. Intake leak causing AFR to be off.

2. I've seen the same symptoms when one coil is not producing proper spark. It sparks, but, not enough spark on one coil. Just because they are new, doesn't mean they work properly. Check the resistance on both coils (static). See if they are about the same.
If you don't have a spark tester or proper ignition tester, pull plugs and test dynamically while cranking engine. See if spark is weak or red on each plug. Also, check coil and kill wire for short to ground.

Sep 24, 2023#80

S

smallenginesmd

Turbodriven said:
Can anyone help here?

I'm absolutely baffled by this issue. I am now 100% out of ideas. The problem presents itself in two ways.

1. Within the first few moments of average load mowing, the motor RPMs dip significantly (about 5-10 seconds after engaging everything ). The greater the load, the more the RPMs dip. I hooked up at tachometer and it shows 1200 at low idle, 3600 "high idle", and during mowing it will usually sit right around 1700 RPMs depending on load (barely enough to mow). If it's a downhill, it'll go to 2500 or so, and small uphills dip to the point of basically being at low idle speed. If at any point I pull back the sticks to a stop (blades engaged), rpms will slowly pull back up to 3300+ RPMs (in 3-5 seconds). Push the stick forward and it dips back into the 1700 range.
2. Using clean plugs, cylinder #1 plug is always turns sooty black (carbon fouled) after a ten minute mow. Cylinder #2 is white to very light brown (varies). But never rich like #1.

I've put together a spreadsheet to track this problem. Just because after checking EVERYTHING I wanted to make sure I didn't miss anything. I know it's a lot, but it will show that I've tested all the typical problems.
The mower is a 2005 Gravely 260z (zero turn) that I bought a month ago for cheap.
I'm completely at my end here and would be happy for any experienced ideas.

View attachment 66771

Sep 24, 2023#81

S

smallenginesmd

Turbodriven said:
Can anyone help here?

I'm absolutely baffled by this issue. I am now 100% out of ideas. The problem presents itself in two ways.

1. Within the first few moments of average load mowing, the motor RPMs dip significantly (about 5-10 seconds after engaging everything ). The greater the load, the more the RPMs dip. I hooked up at tachometer and it shows 1200 at low idle, 3600 "high idle", and during mowing it will usually sit right around 1700 RPMs depending on load (barely enough to mow). If it's a downhill, it'll go to 2500 or so, and small uphills dip to the point of basically being at low idle speed. If at any point I pull back the sticks to a stop (blades engaged), rpms will slowly pull back up to 3300+ RPMs (in 3-5 seconds). Push the stick forward and it dips back into the 1700 range.
2. Using clean plugs, cylinder #1 plug is always turns sooty black (carbon fouled) after a ten minute mow. Cylinder #2 is white to very light brown (varies). But never rich like #1.

I've put together a spreadsheet to track this problem. Just because after checking EVERYTHING I wanted to make sure I didn't miss anything. I know it's a lot, but it will show that I've tested all the typical problems.
The mower is a 2005 Gravely 260z (zero turn) that I bought a month ago for cheap.
I'm completely at my end here and would be happy for any experienced ideas.

View attachment 66771

You're overthinking the issue. If it runs you have to look at the basics. KISS(keep it simple stupid)
1) check cyl compression Should be close in both cylinders.
2) Spark: Solid blue visible
3) Clean fuel, no contaminates : water, dirt, old
4) Good constant fuel flow: disconnect line at carb (into a container) remove plugs and crank engine
5) Check that throttle cable is not slipping/moving under load (very common)
6) Perform all the above with belt(s) disconnected from deck/clutch: If engine runs strong connect belt(s) and run again.
If problem returns look for issue(s) with mowing/drive system.
PS: Remove top engine cowling/cover. Make sure no rodents have built a nest on top of your cylinder head(s) Another common problem that causes engine to run hot / poor performance
Retired owner of small engine shop for over 15 years .
Marc

Sep 24, 2023#82

S

STEVES

Turbodriven said:
Line 30 and 31 of my OP checklist sort of verified that at least the intake seal isn't leaking (and this motor has no seal on the exhaust valve by design). But I removed the #1 valves yesterday and they don't seem loose in the guides. Not tight, but not loose either. Guides are positioned vertically in the heads correctly too and haven't slipped. And leak down confirms that the exhaust valve is closing properly.

At this point I just think my motor is possessed by a demon. Nothing but a slightly out of spec cam is the only thing I see even remotely 'wrong'.

My thought was piston on intake stroke sucking oil by intake valve stem seal. Not the static testing.

Sep 24, 2023#83

L

lefty2cox

This is awfully reminiscent of a fuel starvation issue under load. I'd be curious to find out how TobyU's suggestions panned out. Whether or not that throttle plate was actuating when under load. Could it be as simple as a loose or poorly positioned throttle cable anchor point? I read through all of the posts and didn't see anything relating to eliminating that. I apologize if I missed it or if this is off base.

Sep 25, 2023#84

Turbodriven

lefty2cox said:
This is awfully reminiscent of a fuel starvation issue under load. I'd be curious to find out how TobyU's suggestions panned out. Whether or not that throttle plate was actuating when under load. Could it be as simple as a loose or poorly positioned throttle cable anchor point? I read through all of the posts and didn't see anything relating to eliminating that. I apologize if I missed it or if this is off base.

In my OP checklist I put a string on the governor lever (which is of course attached to the throttle) and under the rpm drop under load I pulled on the string to no effect. Full throttle has the throttle plate fully open (verified). So that tells me the throttle is full open under load. Also says to me that the governor isn't weak and backing things down under load either. When I got into the motor this was confirmed. Governor lever isn't binding, and the gear/flywheel assemble operates as it should with no defects. Also, fuel starvation wouldn't be my number one answer because I'm getting thick carbon fouling on the #1. Which at a glance and from other tests doesn't appear to be from oil. So I can't be rich and lean at the same time. That said, when I put this engine back together with a fresh rebuild I'm going to tear down my carbs piece by piece and make sure everything is right in there too. Might switch back to the (cleaned) OEM carb even.

That said, there have been a lot of people suggesting things that have already been covered. Like head gaskets. They are new. So I apologized if I didn't respond to everyone.

Sep 25, 2023#85

T

toolman034

Have you checked valve stem clearance that is very important for peak power? I did a repair not too long ago that had zero clearance the motor would still run but had very little power. That was due to wear in the seat and causing the valves to open too early and closing late alowing fuel to escape. I ground the stems to regain the clearence and the motor straightened out an run as it should with plenty of power. The almost same would happen if you had too much clearence it would cause the valves to open late and close early. Just a expierance that I had that may help.

Sep 25, 2023#86

Turbodriven

OzPete said:
Worn valve lifters will give that symptom. They are Hydraulic Lifters, and they wear out.
We had a similar issue on a CH740 in a Walker. Replacing all four Hydraulic Lifters resolved it straight up.

I'm replacing the one with wear on it (see post #52), and I'm disassembling the other three and cleaning them. That said, I've pulled one apart already and it looked super clean with no issues.

On that note however, and I talked with someone else about this too, but I'm not 100% sure what kind of oil this had when I bought it. It looked like new oil, but maybe someone put some crazy wrong oil in it. Not totally sure how even the worst oil weight would cause this, but I know these lifters require a certain type to operate correctly for sure. So in the rebuild, I'm definitely going to eliminate this by confirming that the correct oil is in it.

Sep 25, 2023#87

L

lefty2cox

This one is a stumper. What about the safety circuit? Can that end up intermittent and cause this? Or would that sound more rough rather than the smooth drop you have in RPM. Both the hand levers and the blade require bum in the seat. Have you tried to disable the seat safety temporarily? I apologize if this has been covered.

Sep 25, 2023#88

Turbodriven

lefty2cox said:
This one is a stumper. What about the safety circuit? Can that end up intermittent and cause this? Or would that sound more rough rather than the smooth drop you have in RPM. Both the hand levers and the blade require bum in the seat. Have you tried to disable the seat safety temporarily? I apologize if this has been covered.

It has not. However the seat is already disabled. I'll double check but I'm pretty sure it's just the two seat switch wires twisted together and insulated. If there was something "off" in that I'd feel like it would cause problems in all levels of operation though.*shrug. And certainly wouldn't cause carbon fouling on only #1.

That said, I've got this gut feeling that #1 carbon fouling might be a red herring of sorts. One thing brought up to me was that neither side runs well with the other unplugged. It's not like #2 runs great when #1 is unplugged. They both struggle to idle when run independently. That said, whatever is wrong is affecting both cylinders. Just affecting them a little differently. Perhaps just because of the design of the motor. #2 is lower with a slightly longer intake runner (being a cv motor). In any case, seeing #1 black and sooty and #2 white/tan initially made me think this was a problem with only #1. Now I'm not so sure.

In the end here soon though I'll have a freshly rebuilt and inspected motor. And if that doesn't fix it then I'll know that it HAS to be something else besides the motor.

Sep 25, 2023#89

L

lefty2cox

Gotchya.

Again, this was a long one so sorry if this was also covered and I don't remember, but did you do a leak down 1/2 way down and at the bottom of the stroke?

Sep 25, 2023#90

Turbodriven

lefty2cox said:
Gotchya.

Again, this was a long one so sorry if this was also covered and I don't remember, but did you do a leak down 1/2 way down and at the bottom of the stroke?

No, I didn't. Just TDC. I guess it's a moot point at this stage since I just honed both cylinders for new rings. However I will say that both cylinders looked really good. A bit glossy but with visible cross hatching in both still. No scoring or anything. I don't have any bore measuring tools but I don't see any reason to suspect anything wrong.

Sep 28, 2023#91

V

VegetiveSteam

Turbodriven said:
I just honed both cylinders for new rings

You might already know this and I meant to mention it when you first talked about honing the cylinders. After honing them, wash the cylinders with hot soapy water and a stiff nylon scrub brush then rinse with plain water. It's the best way to get rid of the honing grit.

Sep 28, 2023#92

Turbodriven

VegetiveSteam said:
You might already know this and I meant to mention it when you first talked about honing the cylinders. After honing them, wash the cylinders with hot soapy water and a stiff nylon scrub brush then rinse with plain water. It's the best way to get rid of the honing grit.

Yeah, she's clean. I'm on hold waiting for a ring compressor in the mail today. I'm used to just pinching in 2stroke rings but this oil ring ain't having it.

Sep 30, 2023#93

T

tedshred

I've split a couple beer cans and used a hose clamp to compress rings in a pinch....

Interesting that this entire thread is laser focused on the motor, which seemed to run well in the first video. No hesitation throttling up, sounded smooth at elevated rpm etc

In #19, you mention the engine lagging with drive wheels but no blade engagement. And I think there are a couple other mentions like this sprinkled thru the thread...

I'm not a mower guy, just a mech eng who likes this stuff better than netflix...but the engine dipping with drive wheels only would point to something making the hydraulic pumps working harder than designed. Wrong oil viscosity, plugged filter, bad pump bearing, general system neglect, collapsed hose, etc

Wouldn't have to seem excessive on its own, but when combined with blade engagement, the load package might be asking for more oomph than is available from the Kohler

When the landscapers in my neighborhood go ripping around when not mowing, their engines barely sound loaded up when they engage the sticks, and immediately recover rpms as they scoot off.

I am curious to see how the rebuild changes things...

Oct 1, 2023#94

B

bertsmobile1

Unless towing the engines is running on the idle circuit till you engage the blades
This is common with most tractors & mowers, no effective load till it does some work , mowing, plowing etc etc
So your observation is quite correct .
Often I get engines with a blown head gasket that run fine till the PTO is activated .

Oct 1, 2023#95

Turbodriven

tedshred said:
In #19, you mention the engine lagging with drive wheels but no blade engagement. And I think there are a couple other mentions like this sprinkled thru the thread...

I'm not a mower guy, just a mech eng who likes this stuff better than netflix...but the engine dipping with drive wheels only would point to something making the hydraulic pumps working harder than designed. Wrong oil viscosity, plugged filter, bad pump bearing, general system neglect, collapsed hose, etc

Wouldn't have to seem excessive on its own, but when combined with blade engagement, the load package might be asking for more oomph than is available from the Kohler

Well, I think we can rule out the engine/carbs. After a full rebuild there is no change. I found some little things during the rebuild that were not perfect but fixed them as I went through it. The engine is operating as it should. But the problem still exists. An interesting note. When I run the motor in the garage for 5 minutes, both plugs come out golden brown. When I mow with it, and she bogs down severely, I come back with carbon black #1 and pure white #2. I now believe this is just the behavior of this engine when it's at full throttle but externally bogged down. Somehow all the fuel ends up in #1 because the intake runner is shorter? I'm guessing of course, but it must be so.

Also, as noted before, when the blades engage the rpms dip for a second into the 2500-2800 range but then come back up fairly quickly. I believe this is normal behavior. When I hear lawn guys engage blades I feel it sounds the same. My old lawn tractor had the same behavior even. Coupled with the fact that the spindles all spin free with no obvious binding (checked when belt was off), I think we can rule out the deck/blades/PTO.

Which seems to leave only one thing as you mentioned. The Hydro system. I may open a new thread in the transmission forum but for the sake of this thread I'll go into it here too. What would cause a hydraulic system to have excess load?? I don't believe a clogged filter would do this as all filters should have a bypass valve. The fluid on the dipstick looks clean and of the right consistency (tank fluid compared to the bottle of manuf. recommended fluid that I have)

This mower has two separate pumps (L and R) that each run an independent wheel motor for it's respective side. In addition, the left side operates a hydraulic deck lift. (I'll attach a diagram).
1. That said, when I start mowing it seems like it takes about 10-20ft before it falls on its face. I feel like this points to a blockage of some sort (ie: runs great until pressure builds up and forces the system to bind somehow)
2. However, when on jack stands, operating the left stick full forward has no effect on rpms. Wheel spins like it should and literally the rpms don't even dip 1 rpm. Same with the right stick. So that indicates the blockage only occurs under load? See #3 next...
3. When mowing, operating the left stick (only) full forward causes rpms to drop to well under 2000. Same with right stick (only). No difference between the left and right. Remember each side is it's own independent system. On that note: I hope my lawn forgives me, it now has ruts.
4. As mentioned before, when mowing and the rpms drop, pulling the sticks back to neutral brings the rpms back to 3400+ (within a few seconds).

I don't know. Seeing that the left and right side both exhibit the same behavior, it makes me thing the problem is in the tank or filter part of the system. Maybe the filter is fubar'ed (maybe the bypass valve is not functioning in it)?? I guess I can buy a new filter.

I'm just so over this thing at this point. I'm real close to quitting and just parting her out.

Oct 2, 2023#96

K

ksvondrak

You say you ran it for about 5 minutes and both plugs looked the same, but after driving for a while #1 was black. Did you try just letting it run for 5-10 minutes with blades engaged only and then check plugs? If they are still the same, then definitely I would think something with hydros.

Oct 3, 2023#97

Turbodriven

ksvondrak said:
You say you ran it for about 5 minutes and both plugs looked the same, but after driving for a while #1 was black. Did you try just letting it run for 5-10 minutes with blades engaged only and then check plugs? If they are still the same, then definitely I would think something with hydros.

I don't think only having the blades engaged while sitting still would constitute a real load. The rpms with the blades engaged were 3400+ just sitting there (that's why I ruled out the deck being an issue).

It's a moot point at this juncture anyways, I just sold it. I sold it for more than I had in so that's good at least. Thanks everyone for the help, I just couldn't keep throwing resources at a ghost. Sad that I'll never know what the real issue was though. Maybe the next guy is smarter than me (us).

At least this thread will provide someone in the future a roadmap of things to check when they have a similar condition as this.

Oct 3, 2023#98

K

ksvondrak

Yeah, I wouldn't think that would be much of a load either, but just figured 1 more way of ruling out motor and proving a load issue.

Glad you were able to sell it for more than you had invested.

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CV740 27hp bogs severely under average load

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