Kohler Command CH940 ACR mechanism

[makallio85]

Hi all,

I am working on very fresh Kohler Command CH940 engine and I was like 120% sure that it has ACR issue as it couldnt crank past compression stroke at all and engine is really hard to turn even with 2 hands. Without plugs, cranks just fine. Exhaust valve didnt open during compression stroke (as i thought it would, to relieve a bit). Starter wasn't really ruled out, but as it dealer said that cost for it is 400, I thought that maybe there is something else happening here. At least worth to check.

As i have understood from service manual ( http://www.kohlerengines.com/engines/onlinecatalog/pdf/sm_62_690_01.pdf ), it has ACR. But when I pulled crankcase cover and took cam out, I was surprised. Didnt find anything related to ACR.

So my questions are:
- Is there ACR mechanism in this engine?
- If there is, how it is supposed to work?

Engine has only less than 20 hours on it so i wonder what could cause this kind of issue.

Thanks in advance!

 

[StarTech]

First you must re-read the manual. You have a Command which uses hydraulic lifters and there is no ACR involved.

The section you are referring specifies Command vs all other Kohler engines. Even the single Command engines don't have an ACR.



BTW you have the option of using a DB Electrical starter which is the same J&N starter.

 

[makallio85]

Thanks. My bad then - why it is so hard to read manuals carefully Well at least experience is gained.

I presume it is starter then - cant think about any other option.

 

[StarTech]

First I would making sure it is not a bad electrical connection or bad battery (low charge or just plain bad) before assuming it is a starter problem.

Of course yesterday I was just to move a customer mower that been sitting for 4 weeks. It would only whine. First I found the positive cable end at the battery bad then I found the starter locked up from rust. I did notice that last time I first it that starter seem to hang up for a little bit. Oh well a couple new starters now on order. One for the mower and one for the stock shelf.

Thought I had them but I haven't gotten to that area of this year's inventory yet. Last movement was back in 2018 and I had a programming induced error in 2020 so I not surprised they are not there.

 

[makallio85]

Yeah, i already provided power with booster pack directly to starter terminals. Still cranks slow.

thanks for help!

 

[bertsmobile1]

There are a lot of junk 2 pole starters out there
Worth pulling it apart & checking the brushes
Magnets are ferrite and very soft so easily damaged
Also watch it closely with blower housing removed to see if it is the starter pinion that is giving you grief
The original starters were upgraded to ones with an extra tooth on the pinion to give them greater mechanical advantage.
I found that out the expensive way .

 

[VegetiveSteam]

Maybe a bit late to this party on this one but, try cranking the engine with the spark plugs in and the spark plug wires off. You'll still be cranking under full compression but it will take the ignition out of the equation. If it cranks fine with the plug wires removed, your starter and the connections are probably fine. Some of those big block Kohlers had a weird ignition timing issue that affected a small enough number of engines that Kohler never bothered trying to figure out what was causing it. If it cranks fine with the plugs in and wires off I know of at least a partial fix.