Low Hour Kohler CH20 Burning Oil

[Morkai]

The CH20 in my GT2544 starting burning oil on the right side and smoking a lot. (see pic of right plug) It has less than 200 hours on it.

I don't have a leak down gauge, so I haven't been able to do that yet. I checked vacuum at the dipstick tube and it was fluctuating around 1-2".
I heard about the reed valve problem on the twins causing them to suck in oil and burn it, but I would think that would be in both cylinders. Is it possible it blew the head gasket? I sure hope I don't have to rebuild this thing with under 200hrs on it.

 

[Billrog]

Is the air filter clean they'll heat up and smoke it it's plugged up?

 

[Bob_Bainbridge]

My 2004 3235 with Kohler Command 25 had the same problem. It blew a head gasket with 300 hours and I found the head bolts were barely tight. I replaced gaskets, torqued the bolts, ran it up to operating temperature and retorqued them. I had no further head gasket problems but the right cylinder started fouling the plug with burnt oil and had to be cleaned monthly. I never did a compression check but power and sound seemed normal. At 550 hours the front seal went and would leak out 1 quart of oil during a 2-hour mow of an acre. The dealer said it would cost $500 to replace the seal, requiring the engine to be pulled. With the oil leak, the bad cylinder and then the vacuum PTO actuator went bad, I decided to trade it in on a 2015 XT3-GSX.

Bob B.

 

[RandyT]

Lets start with a compression check on both cylinders. You can do compression check on the command because there is no compression release. If you don't own a gauge you can get free rental at most auto parts stores. The 1-2" of vacuum is low but is that with a mercury gauge or water gauge. Small engine manufacturers use water vacuum, not mercury so I don't know what your actually readings are.

 

[Morkai]

I am leaning towards head gasket or valve seal. I was afraid the excessive dirt had gotten into it and wore the rings, but it would probably be bad on both sides.

I do have a compression gauge, I read something about the ACR and figured that was a no go. I remember it looking pretty good. I'll get some readings on both cylinders today. Is it better to do it with both plugs out or one at a time?

Vacuum is in inches of mercury. I was mainly checking to see if it had a vacuum or pressure. My finger test had suggested vacuum. I wasn't much it was bouncing back and forth with the pulses between 0-2" mostly in the 1-2 range. I do have a 3225 with a CH22 I can take a vacuum reading on to compare.

 

[RandyT]

Perform the compression test with both plugs out and the Command engine doesn't have ACR.

 

[Morkai]

BTW, it's a CH20S spec 64638

I got a max reading of 170psi on both cylinders cold. I did see fresh oil on the right plug and even the adapter after running the comp test. It looks like the breather tube has some oil inside it too. So maybe it is sucking oil up through the breather. Is there any reason why there would be more oil going to the right cyl?

 

[RandyT]

Kohler has readings for a warm engine which normally create lower readings than cold engine. I suspect you have a head gasket issue on that cylinder.

 

[Morkai]

Kohler has readings for a warm engine which normally create lower readings than cold engine. I suspect you have a head gasket issue on that cylinder.

I am inclined to believe you. I pulled the breather cover and the reed looks ok, but there is oil all in there the filter looks soaked and there appeared to be oil in the breather hose. I'll bet it blew the gasket at the oil drain and is blowing back through the crankcase, but that cyl sucks a lot more oil back in on the intake stroke than both are getting back through the carb. I guess there's only one way to find out, pull the head. It's head 1, on the right side.

When I lookup the head gasket I get p/n KH-24-841-01-S. That looks like the oem gasket, isn't there supposed to be an updated version? Or is that only for the 25 and above?

 

[RandyT]

That was for the larger engines. the head gasket issue was on the 25 hp engines and didn't effect the smaller engines.

 

[Morkai]

It's not the head gasket, looks fine to me. That leaves me with valve stem seals. I think the intake was leaking based on what I'm seeing, added some pictures.

 

[RandyT]

the cylinder walls looks really smooth. Is there any crosshatching left or has it worn off. How bad of a ridge do you have at the top of the cylinder. And what does the other side of the head gasket look like,

 

[Morkai]

The gasket is the same on both sides, no problems visible. I can see a few of the crosshatching marks still, but most are gone. I don't know what you're referring to about a ridge, there is nothing other than the bevel at the top of the cyl wall. There is no ridge in the wall itself.

If the intake valve seal is leaking will I see any sign inside the intake port?

 

[Morkai]

Pulled the intake valve and the seal looks good from what I can tell. I can feel resistance sliding it though the seal as compared to just inside the guide. I also checked the cylinder bore, if I got my gauge calibrated right, and got about 3.0325 give or take .0005. Looks like it's close to factory specs.

Looks like all I'm left with is the rings. I guess I'll be ordering an overhaul kit and rings, or piston/rings.

 

[rcbe]

morkai/Randy - at the risk of perpetuating one of those old wives tales, is the any possibility that using syn oil vs dino oil is involved here? Not too long ago, kohler was cautioning owners to stay with dino for the first 100 hrs or so before switching to syn... as I remember, kohler was concerned about rings not seating..

 

[RandyT]

morkai/Randy - at the risk of perpetuating one of those old wives tales, is the any possibility that using syn oil vs dino oil is involved here? Not too long ago, kohler was cautioning owners to stay with dino for the first 100 hrs or so before switching to syn... as I remember, kohler was concerned about rings not seating..

Kohler was saying not to use synthetic for the first 50 hours because they were concerned about rings not seating, but that has been removed from the owners manuals and service manuals in the last 6 months. I think if it was a synthetic oil problem is would be effecting both cylinders.

 

[RandyT]

Pulled the intake valve and the seal looks good from what I can tell. I can feel resistance sliding it though the seal as compared to just inside the guide. I also checked the cylinder bore, if I got my gauge calibrated right, and got about 3.0325 give or take .0005. Looks like it's close to factory specs.

Looks like all I'm left with is the rings. I guess I'll be ordering an overhaul kit and rings, or piston/rings.

can you move the piston in different directions. Maybe you can see what the top ring gap is and have a better idea of if it is worn rings. You mentioned you thought the intake gasket was leaking on that cylinder, so that can cause wear and effect one cylinder.

If you pull the piston out remove a ring from the piston and then slide it down in the bore, and see what the ring end gap is.

 

[Morkai]

I do run Mobile 1 10w30 in it, but only after the normal break-in period...can't recall the hours. I think the rings are seated, has good compression and power, and the oil usage came on quickly this last year, I would say before 180hrs it never used a drop. It may be burning some oil in #2, but if it is, it's not enough to foul the plug out bad like #1. Did I mention that it's a 2005 model?

I wouldn't think the top ring would be bad with the compression I was getting. I'm thinking either worn or broken oil ring. I can try and see it though. Not the intake gasket, I was wondering about the intake valve seal, unless that's what you meant. Best I can tell by appearance and sliding the valve through it the seal seems good. I'll get some pics of the seal and valve tomorrow. I did see some burnt marks past the seat and plenty of carbon or something on top of the valve.

I'll definitely check the gaps when I pull them. I thought about popping a new seal and head gasket on it and trying it again and then with heavier dyno oil. If that stopped it I'd know it's the rings. I guess I should've tried that first.

 

[RandyT]

This may seem strange, but here goes. You mentioned that you thought the intake valve stem seal was leaking, I am now wondering if the head doesn't have a casting flaw that is allowing oil to seep down around the valve guide itself, kind of like a crack in the head.

Has a head on a CV23 a couple of years back that was leaking oil externally, but was found to have a casting issue and the oil was seeping through the aluminum from the push rod gallery just below the spark plug. I am possibly thinking a hairline crack next to the intake valve guide. Look it over closely. May only leak when the engine is hot.

It is very unusual for the horizontal engine to have oil usage from around the rings, because they are not that close to the actually oil, unlike the vertical. Most oil usage is from blowby through the intake and would be burned in all cylinders.

 

[Morkai]

No cracks or anything that I can see. It's definitely not the seal, it's good and tight.

The top ring gap looks way out. I don't see how it had good compression, unless the 2nd ring is better. No way to measure without pulling it, but it looks over .050"