Overheated Tractor - Where to start

[bjr]

Are grey market Yanmar engines THAT expensive? I'm shocked. I would have thought there would be a canyon full of donors with the influx of containers of grey tractors. Is there no aftermarket rings available, eg Hastings or Perfect Circle, Mcord gasket hopefully? I would be thinking different tractor at this point. The tractor may bring more for parts and just go get another tractor with that money. bjr

 

[wrenchturner]

Sorry to hear about your overheated engine. I would like to offer you a piece of advice. When the machine shop rebuilds the head, make sure he checks the valve springs. When an engine overheats the heat from the exhaust valve goes into the springs and cause them to weaken. I learned this the hardway. Worked on an engine that had a head job done by another shop due to overheating. Engine would run good until about 1800 rpm then start misfiring. The other shop could not find the problem. Good compression, and everything but at around 1800 RPM the valves began floating. I kept going in circles till I did a running compression test. Anyway, the other shop was not too happy with the machinist when I told him what I had found.

 

[SailorBob]

Sorry to hear about your overheated engine. I would like to offer you a piece of advice. When the machine shop rebuilds the head, make sure he checks the valve springs. When an engine overheats the heat from the exhaust valve goes into the springs and cause them to weaken. I learned this the hardway. Worked on an engine that had a head job done by another shop due to overheating. Engine would run good until about 1800 rpm then start misfiring. The other shop could not find the problem. Good compression, and everything but at around 1800 RPM the valves began floating. I kept going in circles till I did a running compression test. Anyway, the other shop was not too happy with the machinist when I told him what I had found.

That is a good idea. New springs are cheap insurance. I will add that to the list of parts that I am going to replace.

i am also toying with the idea of replacing the cylinder liners too. I don't want to spend any money that is unnecessary but, I don't want to have to tear it down again later either.

I think I found the source of the knock. One of the piston rods had a lot of play on the piston pin. I can wiggle it and feel the slop in it