Export thread

Afternoon folks, hows everyone been running?

Recently just came across a john deere las100 with about 600 hours on it. It starts fine, runs great for about 15-20 minutes than seems to lose power. It doesnt surge, and it apparently only started happening after a few cuts in the spring.

Any ideas of what this issue may be?! I have yet to do ANYTHING to it, i will start in the morning (to damn hot right now 36 celcius)

What troubleshooting steps would you take?

Any and all recommendations are greatly appreciated!

John Deere made a model 100 in the mid 70's with a 8 HP Briggs. Is that what a las100 is. Also when you say losing power just what do you mean by that, starts to miss fire or just dies like its running out of fuel?

https://www.deere.com/en_US/product...wers/lawn_tractors/100_series/100_series.page

I personally havent ran it yet, ill do that in the morning. A friend just told me thats the issue. Starts normal, runs fine, doesnt surge or pulsate so to speak. Ill obviously run through all the normal stuff tomorrow, filters, plugs, etc.

Ill also get an exact model number and a better idea of what happens after 20 minutes of run time!

Old mower, worn rings with oval bore = loss of power when hot.
Old condenser ignition does the same when the cap is pasts it's use by date & gets hot.
electronic ignitions can go the same way.

FPMotorsports said:

https://www.deere.com/en_US/product...wers/lawn_tractors/100_series/100_series.page

I personally havent ran it yet, ill do that in the morning. A friend just told me thats the issue. Starts normal, runs fine, doesnt surge or pulsate so to speak. Ill obviously run through all the normal stuff tomorrow, filters, plugs, etc.

Ill also get an exact model number and a better idea of what happens after 20 minutes of run time!

Click to expand...

So you are saying its a newer John Deere in the 100 series not a John Deere Model 100. It helps to know what year, model and engine John Deere you have with the information as to just what its doing.

Yezzir, LA125, running a 21 hp briggs.

Thank you for the suggestions Bert!

I took a look at it yesterday, theres lots of trimmings and things floating around the gas tank, the fuel filter is crammed full of things. The air filter and plugs were gross. The carb needs a good soak too. I will try these quick easy fixes first, than run it again for an extended period in order to see if there is still power loss. At which point I will look into the recommendations Bert has put forward.

UPDATE: Okay, so over the weekend I put in 2 new plugs, properly gaped. New air filters, new fuel filter (it was disgusting) I drained all the gas in the tank (there was a ton of leafs and things in there) Cleaned it, put fresh gas in. Did oil and oil filter. Cleaned all fins, cleaned everyone, checked hole in gas cap. Its certainly idling much better, it sounds better and has a bit more GO in it when just driving around but the issue from previous is still there....

What happens is that after 15-20 minutes of cutting, (actually using the deck, or under "load" so to speak) the motor loses almost all power. Does not shut off, but reverse becomes super slow mode reverse, and forward the same thing.

Any recommendations?

Just to make sure we are singing from the same song sheet.
Does the mower travel slow or dose the engine run slow ?

If it seems to be mosty ground speed then you are looking at low oil in the box or air in the box .

If it is engine then check you are firing on both cylinders.
If you can also try activating the choke partially.
If the engine runs better with a little choke you still have a fuel delivery problem.
Some times it takes multiple cleans to get all the crud out , particularly f you do not remove the tank completely and clean the outlet from the tank.
JD put pre filters into the tank on a lot of models and yours could be one of them.

Do the cheap & easy first.

The rpm and everything seems fine, starts up just fine no problem from cold. Runs well. sounds great, runs on with the choke on run. But it moves slow, and than after cutting a bit just travels slow.

LA120 John Deere with a Brigg & Stratton engine that moves slow. It has a Tuff Torq T40 hydrostatic transmission. The very first thing I would check is the transmission linkage then make sure the drive belt is OK. As I recall the trans drive pulley tens to strip out on that model transmission but then it wouldn't move at all.

So now that your problem is clear, we can get some where.
I have not seen any L 100's in my shop with a stripped input shaft pulley but I will keep that in mind.
What I tend to see more of is the clutching pulleys coming loose so you do not get full tension on the belt thus the belt slips and the mower goes slow.

So now you will have to drop the deck off and get under the mower.
For these jobs I now drain the fuel tank & remove the battery ( if it is not a sealed type ), then sling the mower up from the front axel and stand it on its rear end.
This will not hurt the mower or engine & makes things a lot easier to work on.
The transmission belt runs very close to the mower and is a bit hard to see almost hidden by the side rails.

The other common slow moving problem is a brake full of crud that does not fully release, also very common particularly if you do a lot of rough mowing ( every long grass, weeds ) or mulching ( stirrs up a lot of dust ).

The rarest problem is low oil but this should be very obvious as you will see a build up of dust & clippings stuck to the oil where it is leaking out of the tranny.
Only 4 places, top pulley ( input shaft ) l & r axels and the control arm, all of which have oil sels on them.

Okay so, today I got the deck off and everything seemed fine there, mower belt looks a bit worn so ill change that just because. Now I have the deck off, and ive went under what should I be looking for?

1. Is there a way to check the fluid in the transmission?
2. How can i tell if the drive pulley, or belt or any of the linkages are out of whack? They all seem tight and fine, the belt and brake so on seem good...
3. There is a electrical sensor or something of that nature plugged into the transmission, could this cause issues?!


What should i be looking for under the mower with regards to my problems?

Also Product Number on side of frame was: GX0120A044346 if that helps!

FPMotorsports said:

Okay so, today I got the deck off and everything seemed fine there, mower belt looks a bit worn so ill change that just because. Now I have the deck off, and ive went under what should I be looking for?

1. Is there a way to check the fluid in the transmission?
2. How can i tell if the drive pulley, or belt or any of the linkages are out of whack? They all seem tight and fine, the belt and brake so on seem good...
3. There is a electrical sensor or something of that nature plugged into the transmission, could this cause issues?!


What should i be looking for under the mower with regards to my problems?

Also Product Number on side of frame was: GX0120A044346 if that helps!

Click to expand...

You should have a Tuftorque 40 transmission and the method to check the oil level is not easy
https://www.tufftorqservices.com/EnvEEdefault/FlatHTML/TechInfo/ttcoil/pdfs/cc%20T40%20MODELS%20CHECKING%20&%20ADDING%20OIL.pdf

with the drive engaged you should be able to turn over the engine by rotating the drive belt.
If it just slips a little when the engine get on compression it is just OK
If it won't turn ov the engine without the spark plug in place, the transmission drive is too sloppy.
You shouls have an adjustment on the fixed pulley on the clutch arm.
Check both of these pulleys carefully as they are plastic and a normal service replacement item as is the belt itself.
Occasionally the clutch spring can go weak but that is not very common.


There is nothing electrical inside the box although you may have a reverse cut out connected to the drive pedal and /or a neutral safety swithc so you ca not start the mower with the transmission engaged although from memory JD put that one on the brake pedal.

You can read the entire factory workshop manual via the support section / manuals on the Deere web site .
However it only brings a few pages up at a time , you can print them out but you can not download & print the entire manual in one sitting unless you are an authorised JD service man.

Completely lost now. Now the effin thing wont start. I have DONE NOTHING to this mower since it arrived here friday except remove the deck. After that it wont start, i had disconnected the battery and now it doesnt start. It has to be boosted so any ideas there?

It also will stall the minute you press down on reverse. Now the steering weel appears to be jumping gears down the shaft when you try and turn the tires.

Like I can fix cars, atvs, snowmobiles but im about ready to roll this Deere into Deere because im completely fu%#^#d here.

Okay yeah, well that was what was happening as well as the fuse being blown. So the motor is starting each time now again. No problems there, the issue with turning right is the teeth on the plate bolted to the bottom on the right turn side are worn completely off. That seems like an easy fix.

Now i ran the mower for an hour PLUS. And cant seem to recreate this guys issue. I am presently uploading a video i made showing all the under workings and such so perhaps when that is ready yall can watch it and see if you can notice or hear anything of note.

Heres the video! HALLLLP! lol

https://youtu.be/TuGeGKnMCiQ

Side note, I measured the belt i took off the mower deck and it was 96"'s on the outside, now the parts look up says the Deere belt # is GX20072 and i am getting ALL sorts of measurements online that are contradictory! Some say 104, some say 108... i measured 96 wtf lol

FPMotorsports said:

Side note, I measured the belt i took off the mower deck and it was 96"'s on the outside, now the parts look up says the Deere belt # is GX20072 and i am getting ALL sorts of measurements online that are contradictory! Some say 104, some say 108... i measured 96 wtf lol

Click to expand...

Go to the Gates site Auto Parts Interchange | Gates Corporation and type your belt number in.
When the equivalent Gates belt comes up click on the gates belt number and you go to a second screen.
Click on the Gates number again & it will bring up the full product details, including the belt length & section.
Unlike 99% of the lists & tables you will find on the web, this inormation is actually correct.

Old british Empire countries ( sing Rule Brittania in your head ) measure belts on the inside circumference in fractional inches.
Rebellious Americians ( sing Star pangled Banner in your head ) measure on the outside circumference in decimal inches.
Europeans measure both circumference and section and specify V belts as mean effective circumference in mm
Clots with no idea make up Excel spread sheets to convert Eng to USA to European and generally get it very wrong then publish their garbage on the web when they instantly become fact.

Next, pulleys wear on the sides which causes the belts to run deeper in the pulleys and effectively go slack.
Authorised service centeres fix this by replacing all the pulleys and the belt $$$$$$$$.
People like me fit smaller belts to take up this slack each service till the belt stats running on the centre so there is a good chance the fitted belt is not the same size as the one it left the factory with.

Further to your belt dilemma
GX20072 is actually 103 & 7/8 inches outside circumfernce.
Most aftermarket belts are whole inches only so most will list this belt as a 104" ( USA ) but some sloppy spreadsheets crop off the decimal so list it as 103"
Then others add 2" instead of subtracting 2" o get an Eng number os it becomes a 105 " (english) which further idiots add another 2" to convert the incorrect conversion back to USA size & you end up with a 107"

You have to be really careful because there are 5 different lawn tractors with 125 in their name
When using the JD parts catalogue it is the numbers on the decal on the side of the hood that you use.
And unless you are really familiar with JD it is always best to use the actual JD web site
John Deere - Parts Catalog

I have no idea which JD tractor uses a 96" belt.
It is listed in the Stens Book as fitting a 50" deck and has an OEM number M41668

Thanks for the info Bert, thats where i got the belt numbers from. The bottom of the seat. GX20072.

But further more, ill just put the belt that was on it back on because the mower was cutting fine and i dont think the belt on the mower deck is the reason why the tractor moves slowly after 15-20 minutes of cutting.

But ive been unable to recreate the problem after 1-2 hours of running it on the block. I am going to replace the steering sector gear.

Any ideas after watching the video Bert?

FPMotorsports said:

Thanks for the info Bert, thats where i got the belt numbers from. The bottom of the seat. GX20072.

But further more, ill just put the belt that was on it back on because the mower was cutting fine and i dont think the belt on the mower deck is the reason why the tractor moves slowly after 15-20 minutes of cutting.

But ive been unable to recreate the problem after 1-2 hours of running it on the block. I am going to replace the steering sector gear.

Any ideas after watching the video Bert?

Click to expand...

GX20072 is a 103.875" belt fitted to the 42" cut deck.
So if the dealer fitted a different deck, it will be the wrong belt for your mower.

FWIW the deck generally does not affect the ground speed unless it is boging down the engine.

So your problem will lie in the transmission belt system or the brake or the clutch or the tranny itself.
So do the tests I outlined earlier.
Check that there is nothing stopping the clutch from fully disengaging
Check that the brake also fully disengages ( note the brake works on the layshaft not directly on the rear axel )
Check that you can turn over the engine by rotating the transmission belt.

From the video it looks like the clutch is not fully disengaging .
The bend between the clutch pulleys should be a lot more S shaped than that.
Go to the JD manual and compare the photos to your mower.

Bert, do you legit feel at this point that those clutch pulleys are the root cause? Read below..

UPDATE:

Well I changed the steering sector and so thats all good to go. Cleaned and put the deck back on. Loaded it on the trailer.. took it to my buddies 2 acre lot to see if i can recreate the problem and sure enough, after 20 minutes or so of cutting the thing just starts crawling. There is no loss in RPM, the motor sounds the same, but after 20 minutes of mowing i began to lose all forward momentum, and reverse doesnt even want to work much at all, soo slow that it barely moves in reverse. If you take your hand and force the peddle down even further it goes a BIT quicker.. for a second or two than back to being slow. The transmission is warm to the touch but nothing outrageously hot.

Any ideas!? I have done so much i think you pros should be able to narrow this down at this point!

FPMotorsports said:

Bert, do you legit feel at this point that those clutch pulleys are the root cause? Read below..

UPDATE:

Well I changed the steering sector and so thats all good to go. Cleaned and put the deck back on. Loaded it on the trailer.. took it to my buddies 2 acre lot to see if i can recreate the problem and sure enough, after 20 minutes or so of cutting the thing just starts crawling. There is no loss in RPM, the motor sounds the same, but after 20 minutes of mowing i began to lose all forward momentum, and reverse doesnt even want to work much at all, soo slow that it barely moves in reverse. If you take your hand and force the peddle down even further it goes a BIT quicker.. for a second or two than back to being slow. The transmission is warm to the touch but nothing outrageously hot.

Any ideas!? I have done so much i think you pros should be able to narrow this down at this point!

Click to expand...

Well it has to be either the tranny or the tranny belt system, one or the other or perhaps a bit of both.
Running the mower on blocks puts no load on the transmission so I am not suprised that you could not recreate your problem.

FWIW the pump in the tranny is a series of tiny little pistons runing in holes .
A rotating face cam pushes these pistons up which pump around 0.5cc to 5 cc of oil each
There are no seals on most of these piston pumps so when the oil gets hot & thin it runs down the side of the piston rather than being pumped by the piston to go on and move the motor.
Thus oil level is very important ,
Clean oil is even more important.
You have not mentioned that you checked the oil level, have you ?
Not sure about your prticular box but they all have at least 1 filter and a lot of them have 2, one external that you can change and one internal that gets changed every time the box is opened up.
Either of these get clogged and it will also act like a low oil situation.
This is Tuff Torques web site, click on the word troubleshooting at the bottom of the page to download the full trouble shooting flow sheet, apparently you can not get directly to the flow chart.
Document Moved
You will find the complete service manual contained within the JD manual for your mower which you can view for free via the JD web site or buy a copy. They are all over Evilbay & Craigs at a slightly cheaper rate but it is all there and available for free.

The direct link showing how to check the transmission oil was in one of my posts a while back.

At this point I've done everything except removing the transmission and checking it's oil. Other folks on different forums suggest even at this point, with 600 hours it's a temporary fix. That doing the tranny oil would maybe get one more season out of it.. Plus doing this probono, I'm not so sure I want to take the huge last step on a hope and prayer. I've read lots of negative things about the t40's.

Alright, transmission is out, its open its drained. Its really clean, no unnecessary movements, no natural disasters so to speak. Tomorrow ill refill it and see!

Any recommendations on what i should refill it with!?

Today i came home.. put a gasket on, filled it with new 5W50.. installed it. Instantly started making a grinding type noise... Pulled it back into the shop.. put it on stands. I also lost all power WITHOUT cutting, so zero load in about 5 minutes this time. Before it lost power the same way.. after 15-20 minutes of cutting..

When i turn A wheel the other turns opposite.. now im not a master mechanic but that seems not right. What I am saying is if i turn say the right axle forward.. the left axle goes backwards. And vice versa. So the tires are turning... opposite directions.

I didnt remove any parts of the transmission when i opened it.. just opened it checked the magnets for shavings, cleaned it real good let it dry over night. New gasket, new fluids. reinstalled..

If you have both drive wheels off the ground and turn one, the other will rotate in the opposite direction. That's how a differential works. It's fine.

UPDATE TIME:

Well folks, after it sitting in my garage under a bed sheet for a month my friend decided to order up the tuff torq rebuild kit (1A646099590) It contained a new center case, motor, pump, all pistons, orings, seals, even gasket maker. So, I pulled it all apart again (3rd time), this time I removed everything, all the internals. Layed them out, cleaned everything thoroughly and went ahead with the rebuild kit. New oil, installed. Runs like a banshee. Cant even keep up to her now. She jerks ya back good and hard when ya press on the peddle.

Very happy to report, that its been two weeks since the rebuild (I wanted to wait before updating, dreading that I would get a text any minute saying "hey buddy, bad news" haha) and everything is still working totally fine!

Thanks everyone for all the recommendations, for all the help and suggestions. You can consider me very well versed in the removal, rebuild, understanding, and reinstallation of the K series hydrostatic tuff-torq transmissions!

Good to hear,
Wear on tranny hydraulics is measured in 10th of thous so without special measuring gear you will not be able to deect it.
Found that out the hard way, big loss on warantee repairs.

So now we know where to send all the Hydro problesm to :laughing:

I just read a pile, and watched https://www.youtube.com/watch?v=YDjhAo6aZ7s video's 200 times. Ready to rock!

Who's youtube channel is incredibly close to your display name...