</font><font color="blue" class="small">( Dare I ask what was going on at the time of failure? That seems like a heat-related failure, or would you attribute it to something else? )</font>
I was mowing one of our tree plantations without problems. I stopped to take care of something. When I restarted the engine a minute or two later, I had almost no power, so the failure seems to have occurred at startup.
Once I took off my hearing protector, it became obvious that something was clattering in the right cylinder (I said left side in my post last night--that was a brain-lock on my part), so I pulled the valve cover and found the bent pushrod. It was no longer under the rocker arm and had been jumping around. The rocker arm stud was loose, and I removed it with just my fingers.
From the discoloration, I suspect it is a heat related failure. I immediately checked the engine shroud for obstructions, but there weren't any. There may have been oil starvation to that cylinder. I'll have to wait and see what the engine shop says before I know for sure.
I can't see any obvious damage beyond the bent pushrod, but that cylinder has no compression whatsoever, so something serious seems to be going on. The owner of the Kohler repair shop that will look into it said it sounded like a valve guide problem, but he hadn't seen the engine at that point, so time will tell.
I did a lot of Googling after this happened and found that the Kohler 25 has had a history of problems. Searching through some of the postings on the sites frequented by the lawn care pros was eye opening. Early on, this engine seems to have had numerous issues, including blown head gaskets, lifter failures, bent pushrods, ignition modules blowing, etc., with most occurring within the first 200 hours. Mine had 110 hours when it went.
Supposedly, all these problems have been taken care of in the current production models. I certainly hope that is the case, and that this is an isolated problem.
We will see.
SnowRidge
