Kohler Command V-twin compression

[92saturnsl2]

I have two used mowers I recently purchased to fix up. One has a Kohler Command 22hp V-twin, CV22-S. The other has, I believe a Kohler 18 horse, same engine.

Just for grins, I tested compression in each, and the two are wildly different. The 22hp reads about 100 PSI in one cylinder, and 110 in the other. The other (18 horse?) reads 210 PSI in each. Both run good, cut good, no noises.

The 18hp with the greater compression does burn a bit of oil, I think it's valve seals as it will smoke just a tiny bit when you idle down the engine from full throttle. One of the plugs was pretty filthy with deposits.

What would a usual compression be for these engines, and should I be worried about the huge disparity between them?

 

[old1]

210 psi for compression sounds unbelievable to me. OPE has compression relief and usually is quite low. I would think that even 100 psi would be very hard for the starter to turn over. I suspect an incorrect reading somehow.

 

[racin4ds]

Originally Posted By: old1
210 psi for compression sounds unbelievable to me. OPE has compression relief and usually is quite low. I would think that even 100 psi would be very hard for the starter to turn over. I suspect an incorrect reading somehow.


This ^^^ Something is terribly wrong either in your gauge/reading or the engine! I've worked on MANY variants of Kohlers when I was a John Deere tech and I've never seen one with compression even close to that! 105-125 is about the norm on these.

If it does in fact have compression that high, then there is MAJOR carbon build up on the piston/head!!

 

[Eddie]

No valve clearance might do this?

 

[oldhp]

Did you release the pressure in gauge before using it again?

 

[bubbatime]

It shouldn't even crank at that pressure.

 

[Eddie]

There is a B&S problem where a starter will not turn over a B&S twin. The valve clearance had closed up and was causing it. Ed

 

[old1]

If the valve tappet clearance is to WIDE it will have to much compression, because the compression release will not work. Pretty common problem that I have fixed many of.

 

[racin4ds]

Originally Posted By: old1
If the valve tappet clearance is to WIDE it will have to much compression, because the compression release will not work. Pretty common problem that I have fixed many of.


Spot on, and so have I. Many B&S V twins suffer from this in all mowers from John deere to Cub Cadets.

 

[jeepman3071]

Originally Posted By: old1
If the valve tappet clearance is to WIDE it will have to much compression, because the compression release will not work. Pretty common problem that I have fixed many of.


Kohler Commands have hydraulic lifters.

 

[4WD]

I had one mower with that engine … got a twin thinking it would run smoothly … not really …
Only kept it a couple years bc a guy offered me a good price …
19 HP B&S one lung now …

 

[jeepman3071]

Originally Posted By: 4WD
I had one mower with that engine … got a twin thinking it would run smoothly … not really …
Only kept it a couple years bc a guy offered me a good price …
19 HP B&S one lung now …


The OHV single cylinder Briggs are fairly smooth running engines.

 

[meep]

my 1957 283 had far less compression than that and refused to run on level ground with any gas below 93 octane. something's not right. carbon?

 

[4WD]

Originally Posted By: jeepman3071
Originally Posted By: 4WD
I had one mower with that engine … got a twin thinking it would run smoothly … not really …
Only kept it a couple years bc a guy offered me a good price …
19 HP B&S one lung now …


The OHV single cylinder Briggs are fairly smooth running engines.

The Briggs has been great ...

 

[92saturnsl2]

Sorry guys, I forgot to subscribe to thread-- missed the responses until now.

I repeated the test a half dozen times because I couldn't believe the results myself. It is indeed 210 PSI in each cylinder, and I did vent the compression tester after each result.

I wish I had taken a picture of one of the plugs off this suspect engine--- the conductors were so shrouded in burned oil / carbon, I wasn't sure how it even fired, but it did. It has new plugs now, but it must go through plenty of oil for one of the plugs to get that bad. Could this be carbon deposits, and if this was the issue, wouldn't the thing knock/pre-detonate like crazy? Is it easy to remove a head and see what is going on inside? I suppose I could rig up a leakdown tester with an air compressor and see what that reveals.

This engine has hydraulic lifters IIRC, so there should be no valve clearance to set, correct?

We have lots of these engines at work powering Lincoln gas welders. They seem to be pretty reliable, only problem I remember is one bending a pushrod for no reason we could figure out. Otherwise they typically go 5,000+ hours with nothing but oil/air/fuel filter changes. I reckon this particular machine (my mower) has a ton of hours, but I don't know why that would result in HIGH compression..? The starter absolutely turns it just fine, so the compression release must be working? I don't know much about how they work.

 

[meep]

compression release lowers compression from max. it won't raise it. It's probably a weight on the camshaft/gear that flings outward once a certain rpm is reached. Until it flings outward, valve timing will be altered to not leave as much air/fuel in the cylinder to compress.

You most likely have several ounces of carbon caked up in the head, taking up space, and hence raising compression. Your nasty spark plug lends itself to that theory as well.

-m