Kohler Command Engine Question

[bjamison]

I've got a Kohler Command engine that I pulled from a Simplicity tractor. I don't find much info on servicing/trouble shooting these engines on the internet, so I thought I'd try posting here to tap into some of your experience with them. I know CCC/MTD used the Command in their 2000 and 3000 series tractors.

Here's the problem:

The engine has no power other than to move the tractor around the yard. If I engage the mower deck, it will bogg down badly.

The engine is oozing oil out of the front main seal and at the overhead valve covers - the crankcase is being pressurized. The engine doesn't smoke and otherwise starts and runs great.

I checked/serviced the crankcase breather and it is OK.

Last night I pulled the engine out of the tractor and removed the shrouds and finally the cylinder heads. There is a little carbon on the pistons, but they look good. The cylinders appear to be in great condition, no scoring and I can still see cross hatching from I guess the factory hone. The cylinder walls are very reflective - almost mirror like. The head gaskets, which I thought might be blown after I eliminated the breather, didn't appear to be breached in any way - allowing pressure back into the engine crankcase via the valves.

So what next? Do I have a bad set of rings?

What do you think is wrong with this engine?

Any help would be much appreciated.

 

[jchamberlin]

Bill: Thinking out loud,

1. If the exhaust was totally blocked, you probably wouldn't even be able to start it; may be partially blocked resulting in significant loss in power.

2. If the engine runs, but dies under load (as you describe),

2.a. Is the governor and linkage working?

2.b.1. Is an adequate fuel supply getting to the carburetor?

2.b.2 If the carburetor is getting gas, is it delivering an adequate flow to the engine? That is, are there issues with the float, the needle and seat, or the main jet circuit? --Has it been cleanded recently?

2.c Is the spark strong? Does it stay strong when the engine revs?

3. As far as the pressure in the crank case, if the breather is clear, the only other passage I can think of for pressure to build up is through the rings. A leak down test would confirm.

Perhaps experienced gear heads may have something to offer, I'm just ticking off theoretical possibilities.

Good luck.

 

[rmcshane]

Ok...dumb question here, but I'll offer...did you make sure the air filter was not plugged?

 

[bjamison]

Thanks guys for the replies.

I'll check the exhaust, but I'm 99% positive it's clear. Governor and linkage are OK. Good fuel supply - gravity feed into a new fuel pump. Carb has been cleaned, including fuel shut-off valve, carb looks very good - almost new. Good spark, stays strong when rev'd too. I don't think you can do a leak down check on a Command as I think it has automatic decompression.

Ryan - air filter is new, so it's good.

I'm wondering if the rings didn't seat or I have read that sometimes with these Commands, if the engine is overheated, the rings will loose their hardness???

At this point, I'm thinking it's the rings.

 

[jchamberlin]

Bill, I may be wrong, but I think the engine has to be turning for the ACR to work, so a COMPRESSION test would not reveal anything, but I know that when I adjust the valves on my M18 I can certainly get them both to seal. But then, I don't think the M18 has ACR, either, and I've never adjusted the valves on the K301AQS or K321 which I think do have the ACR. The Kohler manual tells me there is an adjusting screw for the 10 through 16 UP engines. Anyway, I think you can do a leak-down test, but not a compression test on your motor.

If you think it is the rings, though, you might as well take them out and look at them, it sounds as if you're already there, anyway.

 

[jdiederichs]

Bill, refer to the service manual for the details, it is on the way.

I suspect that one or both head gaskets failed allowing the cylinder(s)to pressurize the crankcase so badly. Yes, these gaskets are a graphoil compound. The new gaskets are a better design than the originals. Now what actually occurs with the old gaskets is that they can develop "worm holes" in the gasket material and dump compression into the lifter bore area or down the oil return passages. That is a good update anyway and will provide long life service for the engine.

The Command horizontal twin as you have is a darned good engine, this will make it better than new.

 

[jchamberlin]

Jim Diederichs: I'm sure glad you frequent this site; you are such a fount of useful information on highly technical subjects. Keep up the good work!

 

[bjamison]

Jim - I got your e-mail, much thanks!!!!

Based on your comments (and my e-mail reply) do you think I need to go further than the head gaskets and forget doing a cylinder bore or hone and new rings - and re-install everything and see if the new head gaskets would do the trick? That would certainly be the easiest/least costly route and if the head gaskets didn't work, I can always go deeper into the engine.

 

[bjamison]

Update: Replaced the head gaskets, re-installed it back in the tractor, but I've got an electrical problem to troubleshoot. The solenoid will "click", but the engine won't turn. I think I've got a loose connection or a not so good ground somewhere. It's dark now - next week or weekend, I'll have a look see at it.