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My first MTD engine (that I know of). It's one a Craftsman 247.203724

Per customer: Smokes on start up. Sometimes a lot. Sometime barely any. Runs good for about 10 minutes then starts to lose power. Has to clean off the spark plug regularly.

When we unloaded it, it smoked like the dickens backing off the trailer. Then cleared up (not all the way) once it was level. (Note: Wasn't much of an incline) Smoked a little more once it was throttled up.
150lbs of compression. No smoke coming out of the oil filler tube (after the engine is turned off). But some coming out of the carb, after it's turned off.

Anyone have any idea's? I'm gonna clean the plug and mower with it for a little bit. Should have more details then.

If the oil is over-full and smells like gas, check the carb fuel shut-off silinoid. I have this same engine and would like to be updated on what you find wrong with it. So far other than haveing to keep the valve lash adjusted it has given me no problems.

The only ways i Know for oit to get into combustion chamber is rings, head gasket, or valve seats. I am not a mechanic and dont know alot so let some of the other pro s on this site chime in.

dfbroxy said:

If the oil is over-full and smells like gas, check the carb fuel shut-off silinoid. I have this same engine and would like to be updated on what you find wrong with it. So far other than haveing to keep the valve lash adjusted it has given me no problems.

The only ways i Know for oit to get into combustion chamber is rings, head gasket, or valve seats. I am not a mechanic and dont know alot so let some of the other pro s on this site chime in.

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No solution yet. But the oil was a little over filled. Maybe a 1/4" over full. When I removed enough to put right on the full mark, I let it run again. No difference. Although it runs rough. This afternoon, I'm going to adjust the valves, and see if that makes a difference. The fact that it turns over great, makes me think the valves aren't out of adjustment.

The smoke had a bluish tint to it. I drained he carb bowl. There was a little trash in it. Changed the fuel filter and shot some seafoam spray into the carb while it was running. Several squirts until it tried to die. Stop, then squirt more. Repeated about 5 times. No change in the way it ran. And the smoke.

The smoke comes and goes.

I ran it until it started running bad. Checked the spark plug (which I cleaned before I cranked it again), and it was still about as clean as it was when I cleaned it. A little more dirty. But nothing major.

It looks like the solution was a valve adjustment. They were way out of whack.
BTW, adjusting these were a little tricky. Get'M set, tighten them down, and the gap gets way too small.
10mm int. .15mm exh.

It runs better for about 10 minutes. Then sounds like it's bogging down while mowing. Release the mower, and she picks up a lot. But not all the way.

Lots of oil in the carb after mowing with it. A couple of times, in some taller grass, it would've died if I hadn't released the mower deck.

Head gasket ????

Is it a Briggs engine ? Craftsman does not make engines..

Boudreaux In Eunice La. said:

Head gasket ????

Is it a Briggs engine ? Craftsman does not make engines..

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It's an MTD 4P90HUB

hrdman2luv said:

It's an MTD 4P90HUB

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Nope MTD does not make engines either..

It is gonna be a Briggs or a Kohler If it's a Tecumseh then it's an older model.

If it's a Briggs OHV the model type and code is on the Valve cover. You might have to clean it to see the #'s

Sounds like a head gasket. Start motor and warm up a few minutes, pull dipstick and check for blowback with motor running, if there is any its prob gasket.

dfbroxy said:

Sounds like a head gasket. Start motor and warm up a few minutes, pull dipstick and check for blowback with motor running, if there is any its prob gasket.

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There is none. I pulled the dipstick just after mowing for like like 30 minutes, and seen no smoke, fumes or any sort.

Boudreaux In Eunice La. said:

Nope MTD does not make engines either..

It is gonna be a Briggs or a Kohler If it's a Tecumseh then it's an older model.

If it's a Briggs OHV the model type and code is on the Valve cover. You might have to clean it to see the #'s

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It's definitely not a Briggs.

Craftsman T1200 Lawn Tractor (2014)
Looking up the number it is a Briggs and Stratton Engine.

Boudreaux In Eunice La. said:

Nope MTD does not make engines either..

It is gonna be a Briggs or a Kohler If it's a Tecumseh then it's an older model.

If it's a Briggs OHV the model type and code is on the Valve cover. You might have to clean it to see the #'s

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It is a MTD manufactured engine in China. MTD has been using a factory in china for engines They oversee the quality control, and assembly, etc. First engines were used on push mowers around 2005, now used on Troybilt,Yard Machine, Cub Cadet, push mowers, tillers, riders, etc. There had been an EFI version since 2015 on select Troybilt, and Cub Cadet riders.

Not Murray, They have to use Briggs engines by contract

ILENGINE said:

It is a MTD manufactured engine in China. MTD has been using a factory in china for engines They oversee the quality control, and assembly, etc. First engines were used on push mowers around 2005, now used on Troybilt, Murray, Cub Cadet, push mowers, tillers, riders, etc. There had been an EFI version since 2015 on select Troybilt, and Cub Cadet riders.

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Intersting. No wonder I was getting all sorts of weird results for that engine number.

Powermore engine is what I found.

hrdman2luv said:

Powermore engine is what I found.

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The is the name that MTD uses for their Chinese engines.

It's a first for me too Never knew MTD made a engine.

Update: installed a new head gasket. and now, no compression. Torgue to 44 ft.lbs. Everything was clean. No problems at all. Adjusting the valves was a little difficult, but after a few adjustments, I ended up with them spot on spec.

Your push rods or 1 rod is not in place. You don't have to take the head off to put them back in the right way, just loosen the rocker arms..

Boudreaux In Eunice La. said:

Your push rods or 1 rod is not in place. You don't have to take the head off to put them back in the right way, just loosen the rocker arms..

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When I was adjusting the valves, they were opening and closing as they should.

What did you set them at ??

If you did the head bots to 44 ft lbs then back then off carefully and retorque between 20 & 25 ftlbs.
If you run the engine with that amount of tension on the bolts they will most likely strip the threads when the alloy gets hot.

Did you check the valves on the inside of the head to see if they seated properly while you had the head off? An unseated exaust valve would cause a no compression issue.

Boudreaux In Eunice La. said:

What did you set them at ??

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Int.05 & Exh .08. The exh was a little tight. But the feeler would still slide.

dfbroxy said:

Did you check the valves on the inside of the head to see if they seated properly while you had the head off? An unseated exaust valve would cause a no compression issue.

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No sir, I didn't. There was a lot of carbon build up. I scraped almost all of it out the a spoon (for the rounded edges). Then wiped what I could with a rag. (I need a new wire wheel for my drill). But, it was getting about 150 before I removed the head. Which is excessive, from what I've read. But still compression.
Now, I can hold my thumb over the plug hole while trying to crank it. I can feel it pushing and sucking. But it's not hardly any.

hrdman2luv said:

Int.05 & Exh .08. The exh was a little tight. But the feeler would still slide.

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Is that MM or thousands ?

Boudreaux In Eunice La. said:

Is that MM or thousands ?

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Thousandths. I think the MM was 10 & 15. Being that there's a 3 thousandths tolerance on these, makes me think it's not real critical. But where I set them was within tolerance. Unless something came loose when I tried to start it.
They were snugged up. I double checked that before I put the valve cover back on. Triple checked the gap.

hrdman2luv said:

Thousandths. I think the MM was 10 & 15. Being that there's a 3 thousandths tolerance on these, makes me think it's not real critical. But where I set them was within tolerance. Unless something came loose when I tried to start it.
They were snugged up. I double checked that before I put the valve cover back on. Triple checked the gap.

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That has the be a translation error.
No one runs 50 thou or 80 thou on the valve lash unless you got a blower and are using nitro.

0,5 & 0,8 mm is aboyt right or even 0.005" & 0.008" could also be right.

bertsmobile1 said:

That has the be a translation error.
No one runs 50 thou or 80 thou on the valve lash unless you got a blower and are using nitro.

0,5 & 0,8 mm is aboyt right or even 0.005" & 0.008" could also be right.

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Yes, translation error. .005 and .008. Could be I got the int. and exh mixed up. But I don't think so. Even if, I'd still get more compression than I'm getting. I hope the head gasket is reusable. I'm thinking I'm gonna have to take the head off again.


What causes low compression?
Valves not seating properly. Possible, but not probable.
Not adjusted properly. Almost impossible because I checked them several times.
Head gasket bad. It's new
Rings gone. Impossible, because I was getting plenty of compression before removing the head.

I did loosen the PCV cover. Because there was two bolts under the fly wheel, I wasn't able to take the plate all the way off. Just loosened it to get a look at the screen under the plate. With the gasket still in position (and looking good) I snugged all the bolts back down.

Going from good compression to none seems strange. A piece of junk that gets caught under a valve will cause those symptoms. Clearance gets set on a valve that is not closing all the way.

ILENGINE said:

Going from good compression to none seems strange. A piece of junk that gets caught under a valve will cause those symptoms. Clearance gets set on a valve that is not closing all the way.

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Ah yes. That is an extreme possibility. I was cleaning the top of the valves. There was a lot of carbon build up. This gives me an idea. I can take the valve cover off, and recheck the lash. If it's still the same. Take the exhaust pipe off, and see if I can see the exhaust valve. Maybe shoots some seafoam in there, and let it set for a while.

How about compressed air through the exhaust? Anything that might me keeping the exhaust valve open, or even the intake, would be loose. For the simple fact that there was compression before.
But in thinking deeper into this, once the valves started opening and closing, (when I tried to start it), should've either been sucked in or pushed out away from the valve seat.

Right? Unless maybe it's now lodged in the valve seat.

What did you use to clean carbon off the inside of the head and the valves? And did you lap the valves after?

dfbroxy said:

What did you use to clean carbon off the inside of the head and the valves? And did you lap the valves after?

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A spoon. Normally a wire wheel. But I need a new one.
Can't see how carbon could get under a closed valve though.

This might be irratating but pull the valve cover off one more time. See if everything looks ok. Then while watching the rockers, turn the motor over by hand. Make sure both have the same amount of travel in both directions.

dfbroxy said:

This might be irratating but pull the valve cover off one more time. See if everything looks ok. Then while watching the rockers, turn the motor over by hand. Make sure both have the same amount of travel in both directions.

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I took the head back off, pushed the valves open by hand (no spring compressor for this type). And blew it out. Let some seafoam soak on the inside and out of both valves for about an hour. Then blew it off again, scraped a little more carbon off from around the valves. Cleaned it up, put it back together. She cranked this time. Smoked like the dickens on low rpms.

Final diagnosis, these engines are crap.

And to answer your question, carbon gets under the valve when the exaust valve opens the exaust goes through the open valve, through the exaust port in the head and out the muffler.

dfbroxy said:

And to answer your question, carbon gets under the valve when the exaust valve opens the exaust goes through the open valve, through the exaust port in the head and out the muffler.

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Well, yeah, I know how it gets under an open valve. But it can't get through a closed one. Which is what happens when the head comes off. They close. If I had 150lb compression, before removing the head, seems that I'd have that much after it went back on.

One thing I forgot to mention in the last update, was the keepers. I didn't pay a lot of attention to them, when I put the new head gasket on. Just sort of stuck in the hole and didn't pay any attention to how deep it went, compared to the other one. So when and torque it down, if it wasn't in there all the way, that would explain the loss of compression.

I did notice some tiny tiny air bubbles coming through the exh valve. That's how I check to see if the valves are seated, spray something around the top of the valve, shoot compressed air towards the bottom of the valve, from the inside. The were so tiny, that I don't think that could've caused the extreme loss of compression. So I'm gonna say it was one of the keepers not seated right.

A quick test is to remove the carb & exhaust pipe.
In a dark place shine a strong torch down the plug hole and look for light in the inlet & exhaust.
As for your worry about how it gets undr the valve when closed. it dosen't.
It falls off and drops under the valve when it opens then gets squashed into the seat when the valve closes

I have been busy prepping some garden beds and repairing some irrigation at our 1/2 garden for the fall and winter garden.

One reason some carbon will get in there is that when you chip away at carbon with a screwdriver and not get it shiny all the way is.................

Combustion in an engine is very powerful, and will cause some flakes and chips to come loose all the time.

Springs on those OHV engines are easily pressed down with some strong man hands. I take the keepers out easy like that myself.

I had to go get me a new BRASS wire wheel today for my drill. I am prepping a 4 HP Briggs for a overhaul. I love doing those 10 and 9 series. Way better than the new E series engines. They are Classics like the old 283 and 327 Chevy engines.

I spend a about 40 bux on new parts and a few hours on one. Get it on a nice frame and get 130 to 150 bux for it......

Hope you get it resolved Mon Ami ~!~!

bertsmobile1 said:

A quick test is to remove the carb & exhaust pipe.
In a dark place shine a strong torch down the plug hole and look for light in the inlet & exhaust.
As for your worry about how it gets undr the valve when closed. it dosen't.
It falls off and drops under the valve when it opens then gets squashed into the seat when the valve closes

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I did shine a flashlight under the valves, best angle I could get, and didn't see any. May have just been the angle. But the bubble test showed some open spots. Extremely minimal. So obviously there was some compression loss from the first go round. The second, after doing what I described, was much better. Enough compression to start it. I haven't done a compression test since I put it together the last time. Calling it quits on this one. It's got more issues that I care to take on. And more issues than the owner is willing to pay for.

I do wish he'd let me keep the engine though. I'd like to "tinker" with it. The other shop in town says they've improved their pistons and rings. Thicker rings now.