Normal compression for kohler 15 HP motor?

[dirtyb115]

Hi all. Just got a craftsman mower for free b/c it did not run. He said it ran, then it would only run for about 20 min then stop. Then finally it would not start at all. It is getting spark, and seems to be getting fuel no problem. I did a compression check and its at 70-75psi. What is normal on these engines? Thanks in advance for any info.

Thanks!
Dave

 

[tcartwri]

100 psi is about the minimum

 

[dirtyb115]

I figured, but had my fingers crossed . Thanks for the info.

 

[oldnslo]

I figured, but had my fingers crossed . Thanks for the info.

Before taking the head off check the valve clearance. As these wear the clearance decreases and this can hold the valves open slightly especially when they get warm/hot and grow some in length.

Not of the exact specs on your engine but would guess around .010 - .012" for exhaust around .008 - .010" for intake.

Roy

 

[dirtyb115]

Thanks for the info, ill try and have a peek at them this weekend.

 

[Bird]

How old is that Kohler engine and which engine model is it? You can go to Kohler Engines and maybe look up whatever you need to know. I recently bought the smallest Toro ZTR mower with a Kohler Courage 15 vertical engine and downloaded both owner and service manuals. Section 3, page 26 (of 132 pages) says an accurate compression test is difficult because of the Automatic Compression Release that changes the compression ration from 9.4:1 to about 2:1 when starting the engine. So they recommend a Cylinder Leakdown Test in which you use 80-100 psi of air pressure to see if it leaks down. Judging by that, your 70-75 psi might not be too far off.

DISCLAIMER: I'm no mechanic so I'm just telling you what I read. But if you follow the above link, you might find a service manual for your engine.

 

[dirtyb115]

Well, went to have a look, its a Kohler Command 14 HP. (not 15...)
Ill try and have a look for the manual and see what i can find.

 

[Jim Thompson]

Well, went to have a look, its a Kohler Command 14 HP. (not 15...)
Ill try and have a look for the manual and see what i can find.

The Command is an OHV engine with hydraulic lifters and there is no valve adjustment. There were problems with both the lifters and rocker arms. There could also be bent push rods if the lifters are bad.

Jim

 

[dirtyb115]

Well getting ready to pull the head off. Wish me luck

 

[Bird]

Well getting ready to pull the head off. Wish me luck

Good luck, and at least it ought to be an interesting experience.