In the "Best Engine" thread I mentioned the Kawasaki engine on my Scag mower had grenaded, I finally got a chance to tear into it and see what went wrong. I pulled the spark plug first to see which cylinder was bad and the end was smashed and full of aluminum chips, at this point I pretty much knew it was fatal. I pulled the head off and discovered a broken valve and lots of shrapnel. This isn't get any better.... I took a look in the cylinder and there was the valve seat in two pieces, along with two holes in the piston. The piston is all cracked in addition to the holes. Lots more shrapnel. A quick look at the cylinder, it doesn't look too bad but I haven't pulled the rod and piston out yet. I also don't know to what extent the shrapnel is spread through the crankcase. After I took the head off, I was surprised to learn it was manufactured in the USA and not Japan.
Hi STeve, I have a Kawi small engine service manual if you decide to rebuild and want to look at it. doug
Looks like your exhust valve let go. You didn't happen to have grass obstucting the flow of air did you? It looks like something has been hot between piston depression in head and outside exhaust port in that second pic.
Thanks DigDug, I appreciate the offer. I don't think I'm going to be attempting repair, bewteen parts cost and my labor I doubt it will be worth it in the end. I've found a new Kohler 25hp engine that will bolt in place for $600, that will probably b the route I go. I'm pretty diligent in preaching how important keeping the air passages clean is to my help, we blow them out almost daily. I can't say for sure that it was never blocked. I'll look at it closer tomorrow and report back. I think what you are seeing is oil residue, something was weeping oil between the cylinders and it got blown around a bit.
$600.00 for a Kohler engine sounds like a pretty good deal.