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Hello everyone.
Just joined and I'm looking for information and advice on my Kohler CH20 Command.

I acquired a nice John Deere F620 FMM with a blown engine @ 1100 hrs.

I located a replacement CH20 (spec. 64638) with 214 hrs. out of a 2544 Cub Cadet.
The original engine was a spec. 3134, I believe.
They appeared nearly identical except for the fuel pump configuration.

I pulled this engine down to the shortblock for inspection, and it was very clean and
reflected what I believed to be accurate hours.

Everything was reassembled per the Kohler service manual, with genuine Kohler gaskets and seals.
I installed it, it fired right up, and it ran beautifully.

I mowed for 2 hours, and it used just a little over 1qt. of oil, and showed a slight amount of smoke from the exhaust.
There are no external leaks at all.

I ran a compression check and a leakdown test. #1@ 105psi. and #2@ 110psi. with minimal leakdown.

I checked the crankcase breather, and the reed valve is intact and appears to be working.

At this point I must admit, I have limited experience with small air cooled engines.:redface:

Everyone I talked to locally suggested I re-ring it. I really didn't know.

At any rate, I pulled it back out, ordered a Std. ring kit and gaskets, along with valve seals, and a set of fresh plugs.
Upon dis-assembly, I found .050 crankshaft end play that wasn't there before.
Kohler spec. is .02 - .023, and I had .015 when it went together the first time.

What I found was a scarred block thrust surface and crankshaft face on the flywheel end.
Has anyone repaired one of these Command blocks?

I'm thinking resurface the thrust area of the block and clean the crankshaft face up.
Can this be fitted with a bronze thrust washer of the appropriate thickness to make up the difference?

BTW, this mower was intended for resale, so dropping in a new $2000 engine is not an option.


Thanks in advance.


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No problem with doing a top hat bush, if you can make it yourself
I would put a hardened thrust washer between it and the crank.
Way back in tme when mowers were expensive and labour was cheap they used to make bushes for cranks.
Now days the labour costs make it uneconomic.
We used to send such engines & those with siezed craknks to Malasya , Indonesia & Vietnam and they used to repair them & use them but even now that is uneconomic.

Thanks for the reply, bertsmobile1.

I did some checking at the local machine shop, and we discussed different ways to salvage this block.
We decided, due the the undercut in the rear crank journal, a simple "floating" thrust washer arraignment wasn't going to work.

We come up with a "lipped" type bushing that would index it's self into the crank journal bore in the block, press fit with red Loctite.
It was going to require over-boring the front 1/3 of the rear main journal bore to create a seat for the new bushing.

All in all, I think that would be a reasonably sound repair.

The problem then, became cost. Approx. $450. The required bronze bushing material came in at $30/in.

Yep, Thirty dollars per inch!:confused2:

It looks like I'll either be looking for a Std. replacement block and crank, or a complete used engine.



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Radar2 said:

Thanks for the reply, bertsmobile1.

I did some checking at the local machine shop, and we discussed different ways to salvage this block.
We decided, due the the undercut in the rear crank journal, a simple "floating" thrust washer arraignment wasn't going to work.

We come up with a "lipped" type bushing that would index it's self into the crank journal bore in the block, press fit with red Loctite.
It was going to require over-boring the front 1/3 of the rear main journal bore to create a seat for the new bushing.

All in all, I think that would be a reasonably sound repair.

The problem then, became cost. Approx. $450. The required bronze bushing material came in at $30/in.

Yep, Thirty dollars per inch!:confused2:

It looks like I'll either be looking for a Std. replacement block and crank, or a complete used engine.



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Click to expand...

Yes, frustrating isn't it.
I use a product called Guard Shaft .
It is basically a continuously cast heavy walled tube of leadded gunmetal 85:5:5:5 if that means anything to you.
Bought from a metal supplier it is around $ 50 /kg for full lengths ( about a meter ) which can go over a grand for bigger sizes.
That price doubles if you buy a slice and you pay for the swarf as well so I get full lengths.
Bought from a bearing supplier I would pay around $ 75/ kg so the per inch price depends upon the diameters.

So it is the same story, unless you have the gear & time to do te job yourself or have a moate that dose th machining for a carton, it is uneconomic.
Particularly when you can buy a remaindered engine for around $ 600 to $ 1000 and break your old engine for $ 200 to $ 300.