Kohler Command 25hp burning oil

Bleach

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I have a 1997 Craftsman 50" riding mower with a Kohler Command CV25S 25 hp and it's burning oil bad enough to foul one of the plugs in less than an hour of mowing. It has just under 600 hours on the clock. Compression seems really good with just over 180 psi on the affected side and a little over 200 psi on the good side when warmed up. It's burning oil on the side with the breather on the valve cover. The breather doesn't seem to be plugged. I've read here somewhere that the reed valve could be a culprit but I only have side that burns oil. I had to replace a the valve stem seals on one of the heads before at around 100 hours but I don't remember which side. It seemed to have fouled a little differently that time.
I would really appreciate some help to point me in the right direction this time around.
Thanks in advance.
 

ILENGINE

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Some of the original CV25 engines had issues with blowing head gaskets. Later models used a head gasket with a fire ring.
 

Bleach

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I'm sure we can rule out any head gasket problems with my compression test results. Aside the oil burning, it runs really good until the plug fouls. I'm still running the original carburetor but I've replaced both ignition coils this past winter.
 

cpurvis

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Oil rings are responsible for getting excess oil off the cylinder walls. You can have good compression and bad oil rings. That's one possibility.

Another is worn valve guides. They won't be detected with a compression test, either.
 

Bleach

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The fouling doesn't happen as quickly when I keep the small hose running to the breather disconnected.
 

bertsmobile1

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So how do you think the oil gets into the combustion chamber ?
The grenlins didn't put it there.
I am sorry there is no can of magic fix sprayed into the air at midnight while dancing naked around your mower.

The compression figures you quoted are garbage the engine does not pack 200 psi brand new.
So you either have a bad head, bad head gasket ( the breather points in this direction ) or bad rings ( only oiling on one cylinder points that way )
One of the 3 or all of the three
 

Bleach

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Bert, I don't know what to say about the compression numbers but they are what they are. I used a good quality compression gauge and it was done with a warmed up engine. I was a little amazed at the numbers myself. I had used the same gauge on one of my cars recently and the readings I got were normal.
 

ILENGINE

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Kohler says that engine should have a minimum of 160 but doesn't give a top number. Just says 160 or above. So your reading may be within the normal range.
 

Bleach

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Other than the oil burning the engine runs good and still has plenty of power. The biggest issue is I'm poisoning myself when riding the mower, especially at higher RPM's. I can deal with fouling plug easily as it only takes a few minutes to remove, clean and replace it. I'm mowing around 2-1/2 acres about once a week now and spending lots of time in the seat.
I'm not about to buy another mower even though this mower has a lot of other issues but it still cuts grass well.
 

Rivets

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I'd also be checking for a bad head gasket on that cylinder, but wouldn't rule out a worn oil seal on the intake valve. cylinder leak down test would give you a better picture of what is happening in the cylinder, without tearing anything apart.
 
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