Kohler CV740 27hp command won't start.

Homer1

Homer1

Well-Known Member
I have been working on an older Command CV740 27 hp engine on a ZTR trying to figure out what's wrong with it. It ran last year but with a little valve noise. Has been maintained as far as I know. This year, it turns over, but won't start. I have already been through a few checks to try and shed some light on it, but I keep coming up blank.

1. Checked and cleaned carb (did not open the accelerator as I don't have a new seal on hand) All jets and flow seem ok.
2. Checked operation of the fuel shut off solenoid, works correctly.
3. Checked fuel pulse pump, working.
4. Checked for spark, and changed plugs, both cylinders, good.
5. Tried to check for compression but came up blank, not sure if I am doing it correctly honestly (using a screw in gauge and turning over a few times) results in zero both cylinders.
6. Checked rocker movement, one valve seems to open half the rate of the other left side when turning engine over by hand.
7. Battery voitage good, 12.4
8. Fuses good (only 2 I can find on entire mower)

Haven't tried starter fluid yet.

I'm not sure if it's something I'm missing or something electrical. The safety sensors all appear to be working, as the engine cranks, and I assume it shouldn't even do that if one of them was not working.

Any suggestions?

Thanks.
 
Ok, starter fluid was a no go as well. Also, when I put my hand over the air inlet and crank the engine, I don't seem to feel any suction at all. I've been reading various topics regarding compression on these small engines, and how to figure out if an engine is just "blown" but I can't really tell. My gauge doesn't move a bit when using the tester on each cylinder. I'd think if the head gaskets were damaged this may cause this symptom, but both cylinders at the same time?

I didn't want to break this thing down all the way, but I am starting to worry the cam shaft is worn which may be why one of the valves isn't opening as far as the other.

with 700 hours on the engine it really makes me wonder if it's a worthwhile investment for me to even rebuild it. These projects are always money pits :-(
 
Well, valves look like they are doing great, but good call on the pistons. Zero movement. Looks like a connecting rod(s) broke off somewhere.

I'll have to break it down next week if I can even find the parts to put it back together affordably.
 
I believe that engine has hydraulic lifters. Requiring no adjustments. Neighbor has one on his Z Master with almost 2,000 hours on it.

But if you are NOT seeing the pistons move at all. It's time for surgery (sounds like).
 
Bad luck on that one
You would not beleive the number of twins that come in with the owner complaining it seem a little sluggish then I find one piston sitting in one side not moving.
 
The no compression would be a very good place to start. A leak down test will tell you what to look for. You need fuel, compression, spark, and timing and it will run.
 
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