Kohler Command CH20

[IH982D]

Hey guys, I've got a Command CH20 twin that's got me stumped.

A little background first.

I picked up a MTD/CC GT2544 rider specifically for the engine and rearend.
It was a clean tractor with 214 hours on a working meter.
It had a dead cylinder, (#2) and got parked for a couple seasons before I bought it.
The PO had removed the #2 head and tin work.
I bought it like that.
Turns out, it was just a bad coil module.

I pulled it down to the shortblock, cleaned and inspected everything, and it looked like new inside and out.
I installed 24-841-01-S head gaskets and swapped the 8mm TTY head bolts in favor of standard Kohler 8mm non-TTY head bolts.
Everything assembled and torqued to the specs in the Kohler manual.
Filled the crankcase with Castrol GTX synthetic 10W-30.
I used this CH20 to re-power another (green) machine, and it is a direct replacement for the engine I took out.

Fired right up, ran beautifully, idled nice, and sounded great.

Ran it around for about an hour, and it dropped one cylinder, ran rough, stalled,
and rolled over hard like it wanted to run on only one cylinder. That was last fall.

I shoved it in the corner and worked on my Cubs all winter.........


Last week, I dragged it out, pulled the valve covers, and found a bent pushrod on the intake side, head #1.
Further inspection revealed it had ingested one of the small bolts that holds the air breather pan on.
Evidently, that's a common problem with the CH Commands.

Luckily, the bolt head was too big to get past the valve, and the threaded portion kept the valve from seating.
Lucky me. LOL!
Fished it out with a magnet through the intake port, put a used pushrod in it, buttoned it all back up,
used LOCTITE on the air breather pan bolts, and it runs great.

I mowed my first mow of the season and it never missed a beat.

Here's the problem.
2 hours mow time, and the dipstick barely shows any oil left......
Used about 3 pints.

Here's where I'm at now.

#1 cyl. has 105 psi.
#2 cyl. has 110 psi.
Leakdown test shows only faint air entering the crankcase
and nothing past the valves.
Zero external oil leaks anywhere
#1 plug shows oil fouling
#2 plug shows slightly rich, but no oil fouling
Reed valve passes visual inspection, but this engine has
excessive crankcase pressure (no measurable vacuum)
Exhaust has faint blue smoke, but you need to be inside the shop under florescent light to actually see it.
No oil in the air breather, but just a damp trace in the breather tube.
No vapor stream, or oil mist out of the breather tube.

So....any ideas what to do next?

J-mech? Anybody?


Thanks, Mike

[Leadslingingdaddy]

They had problems with leaky head gaskets...Is there oil in the air cleaner cover?

[J-Mech]

I'm with Randy. Most likely a head gasket issue. I check cylinder 1.

Did you plane the heads? If not, I'd do that and install a new gasket. That's about the only thing I can think of.

[IH982D]

Thanks for the replies, guys.

I've been scratching my head over this thing the last couple days.
#1 cylinder is where the problem is, I think.
Yesterday, I pulled the #1 head just to see if there was any weird damage
from the bolt sandwich it tried to eat.

The piston and head really didn't look like the plug would indicate.
Pretty clean.
Gasket looked great, as well. No signs of being blown.
Nothing blown into the lifter valley, nothing blown at the oil return. Nothing.

Evidently, the valve did contact the piston when the push rod bent,
but absolutely no sign of damage.

One very small "smudge" where the valve made contact, but it completely
wiped away with a shop towel. It disappeared.
I pulled the intake valve, cleaned it and the seat with Brake-kleen and some Scotch-Brite.
I was careful to wrap cellophane tape around the valve stem so as not to damage the valve seal.
It sounded good when dropped on the valve seat. Nice "POP".

Reassembled the head, filled the intake port with some Brake-kleen, and waited.
Didn't leak a drop past the valve. It's sealing.

Against my better judgment, I Copper-coated the recent head gasket,
put it all back together, and mowed another hour with it.
Used almost 2 pints.

Right now, it's back out and sitting on the bench.......

I really can't imagine bad oil rings at 214 hours???
Especially when I got this engine, #1 was the good hole with a clean plug, and #2 was
slightly gas fouled from a bad coil module.
There was absolutely no sign of excessive oil consumption.
Heads and domes looked normal, inside muffler looked dry.

There was no baked brown stains under the valve covers like it had ever been hot,
and I'm pretty sure it was even full of oil.........

I'm going back down to the short block again and double checking everything.

Ordering another pair of head gaskets, but want to make sure
the part # is the latest updated gasket.
Is 24-841-01-S for sure the latest head gasket for a CH20?


Thanks,
Mike

[J-Mech]

Don't tear the the motor down to the short block. Seems like a waste of money to me.

Don't copper coat the head gasket. Install it dry.

Did you check the head for warpage? Or plane it?

You have to figure out where the oil is going. You can't burn a quart and hour and not see it smoking or leaking. You have to be missing something. I've got a motor that doesn't burn that much and it smokes like a fire.

Does this thing have a electric fuel pump? Or a mechanical one?

Dump the synthetic oil and fill it with regular 30WT.

[gt383mag]

hey J you should post this in your "how to post questions" thread im no help to your problem but you did a great job at covering every base ... wow great info you have done everything i would have done the same way im curious also

[J-Mech]

I agree Mike is doing a great job giving information!

I keep rolling this over in my mind. Put it back together and switch oil. I really think the oil may be the issue. (30wt regular)

[Berwil]

Could the oil ring be stuck in cylinder 1 from sitting a few years?

Bill

[IH982D]

Oops!
Too late.
I already pulled the tin and both heads.
Both head gaskets looked to have been sealed just fine.
I'll straightedge everything when I get it all cleaned up.

Outside of some yard dust, this thing is as clean and dry
as when I dropped it in the first time.

I normally wouldn't Copper-kote a graphite head gasket,
but I was almost certain this would be coming back apart soon.

Kind of odd, but both heads and pistons look about the same
as far as deposits go. #2 plug appears rich........#1 is oil fouled.
Both pistons and cylinder walls seemed to have an over abundance of
oil. Not burnt oil, fresh raw oil. More than you would expect.
Almost reminds me of an old two stroke with a fat injection pump.
Could this thing be ingesting oil into the fuel through the fuel pump?

Reason I ask is, the original 2544 Cub had the integral valve cover mounted fuel pump,
and this machine had the remote vacuum fuel pump on the shroud.
I went with the remote pump and OEM (green) valve cover to keep the machine original.

The original pulse signal for the fuel pump comes from the front cover
just like the OEM engine did. Cub just had a 1/8" pipe plug there.
No baffle or screen behind it that I could find.

On the oil, I figured if it's drinking it this bad, I wasn't going to dump
any more synthetic in it. Last fill was the same Rotella 30W I run in all the other mowers.

This "oily cylinder thing" has me wondering now..........
I was expecting some dry soot on #2 at least.

The heads are untouched. The pistons and cylinders, I wiped most of the oil out of before I thought to get the camera.


Just went out and checked.
The intake, the intake ports, and the pulse hose to the fuel pump have an oily film inside. Exhaust ports are.......#1 greasy, #2 sooty.



Mike

[IH982D]

".........Could the oil ring be stuck in cylinder 1 from sitting a few years?......"


I'm glad you said that, Bill.

I couldn't hardly make myself type it.....

It sure looks like a twin cylinder oil pump to me, too.

If I had to describe what a cylinder would look like if stuck wipers were letting the piston suck oil right out of the sump, it would look like this...

On a positive note, it seems to have good upper cylinder lubrication! LMAO!



Mike