I have a 2004 Kohler Command. At 240 hrs, the rocker arm bolts had loosened-up so much that a intake push rod became disengaged.
The autopsy also revealed:
- The valve dropped onto the piston
- the shattered valve guide shrapnel entered BOTH combustion chambers (i.e., the intake from the other side of the engine sucked some bits of sharpnel into the other head).
- substantial build up of grass BEHIND the cylinder head heat shields.
This is probably a sporadic problem, but I did find posts of others with the same problem I had:
http://www.mytractorforum.com/showpo...0&postcount=12
http://www.mytractorforum.com/showthread.php?t=109071
http://www.lawnsite.com/showpost.php...3&postcount=15
I suspect the rocker arms were either not torqued to spec and/or no Loctite threadlocker was applied to the rocker arm bolts during assembly.
THE GOOD NEWS:
Kohler stood behind their product. On my 6 year old engine with 240 hrs, they sent me no-charge a new short block, new head and new gaskets/bolts. I just had to do the labor to rebuild it and transfer the one remaining good head over.
ALSO.. I removed the cylinder head heat shields on both sides (but retained the blower shields around the flywheel, the top heat shield and muffler heat shield). Now grass doesn't get lodged in the heads' cooling fins.
YOU MIGHT WANT TO: remove the cylinder head side heat shields too and vacuum the grass out.
SEPARATELY, BUT RELATED... On the earlier Commands (late 1990s and very early 2000s) there was a headbolt recall too.
OVERALL, I wouldn't hestitate to buy another Kohler Command engine.
These Kohler Commands are stout machines
I'm amazed mine was still powering the tractor even though one cylinders intake & exhaust rocker arm bolts were substantially unscrewed resulting in bad valve timing and very little valve function.