Kohler command hard start

[StarTech]

I'm under the impression that valve clearances aren't adjustable on this engine?

I assuming this is a CH14. There is only 36 versions to chose from.

Most use hydraulic lifters so no valve adjustment but both do have decompression systems built-in the camshaft. If it fails then you can have hard starting. Just like regular decompression you should see a little movement of one of the valves very close to the end of the compression stroke at TDC as the engine goes into the power stroke. It could be a simple as the spring on the cam has gone missing.

[Ron]

Working on a kohler command 14 hp ohv horizontal shaft engine. Actual model and spec numbers are not readable. It will start fine except when it seems to be on compression stroke. This is in a gravely 14g rider. Battery has been load tested and even switched to rule that out. Starter removed and load tested by a elec shop that works on starters. It tests fine. Seems like a valve issue but these valves are not adjustable. When it is not on compression stroke, it spins over fine. But when you shut it down and it is against compression, it will engage put not turn over unless you keep bumping it.

[Deere2me]

You need to check if the ACR is working. Also check the valve clearances. GET A MANUAL HERE : http://www.kohlerengines.com/manuals/landing.htm

[Ron]

I'm under the impression that valve clearances aren't adjustable on this engine?

[Ron]

I removed the valve cover and watched valves as I rotated the engine. I didn't see any movement of the exhaust valve right after intake closed. I posted a video on you tube. Tell me what you think.
http://youtu.be/e4DYIFPMWo4

[Ron]

I'm pretty sure it is the ACR. I installed plug and tried turning it over with a socket on flywheel cover nut. When I got to compression stroke it was very hard to get past that. I really don't have time to tear into this engine. It looks to be a pretty labor intesive. I assume you pretty much have to take the whole engine apart. I will return it to the owner and let him decide what he wants to do. I'm thinking it will be pretty hard on the starter.

[bgsengine]

Did you follow the diagnostic procedure in the shop manual (Linked earlier by deere2me) ?

You need to test compression and compare to the specs. a hard cranking engine can also be caused by a bad ground - I can't tell you how many times we have fixed a "Cranks Hard" after it has been to 2 or 3 other shops, and 9 times out of 10, all that was needed is to fix a ground problem - easily detected by doing voltage drop test.

Compression test will tell you if the problem is ACR/Valve related (You can't tell by turning engine by hand.) - you'd see compression higher than spec in the shop manual. If it has hydraulic lifters, it could also be a failed/collapsed lifter (rare, though).

[Ron]

I will do at compression test tomorrow. I hesitate to think it is a ground problems. Like I said previously and as shown in the video, there is no movement of the exhaust valve at the power stroke. If there was a collapsed lifter, wouldn't I hear a tapping sound?

[Ron]

Did you follow the diagnostic procedure in the shop manual (Linked earlier by deere2me) ?

You need to test compression and compare to the specs. a hard cranking engine can also be caused by a bad ground - I can't tell you how many times we have fixed a "Cranks Hard" after it has been to 2 or 3 other shops, and 9 times out of 10, all that was needed is to fix a ground problem - easily detected by doing voltage drop test.

Compression test will tell you if the problem is ACR/Valve related (You can't tell by turning engine by hand.) - you'd see compression higher than spec in the shop manual. If it has hydraulic lifters, it could also be a failed/collapsed lifter (rare, though).

Read through the shop manual, didn't see any "diagnostic procedure" about the ACR. It explains how it works and also says
"Compression Test
These engines are equipped with an automatic
compression release (ACR) mechanism. Because of the
ACR mechanism, it is difficult to obtain an accurate
compression reading.
Also, shop manual does not give any compression values. Shop manual---http://www.kohlerengines.com/onlinecatalog/pdf/tp_2402_a.pdf

[bgsengine]

Interesting.. I don't have the specs at hand (Always look ' em up when needed) but last one I can recall, which I do believe was a vertical shaft command 15 HP with the same problem - manual had a compression spec (In the specifications section, if I recall - Ill look it up this afternoon when I get a chance and point out where to find it.) and compression under a working release should be approximately 60% of spec (140 PSI x 0.60 = 84PSI) - So the one I was dealing with had 80PSI so I knew the hard crank was NOT caused by bad compression release.. voltage drop test showed me the bad spot between the engine block and the battery ground cable, since engine was securely bolted down, added a starlock washer to the battery ground attachment point on the tractor frame, problem solved.

- NOTE: that is for the engines that are equipped with compression release..

Some engines are not, and those will have an automotive style starter - the solenoid is integrated directly with the starter - they have a gear reduction for greater torque, *because* they are built for engines that do not have a compression release. - so hard cranking on those, you either got something really binding the engine, weak battery, bad wiring, or bad starter.