Yanmar YM-240 Engine problem

CEY · Feb 23, 2005

I have a question related to the engine on this tractor. It is a 2 cyl. diesel, and I purchased it cheap because the previous owner claims it was overheated, began to labor and he shut it down, and thinks it spun a bearing. It has been run several times since, and the engine does not show any signs of a bearing that is spun and siezed. What it does while it's running is idle rough/irratic, and after running a minute or so, seems like it starts to labor. After shutting it down, the crankshaft turns easily, so the laboring doesn't seem to be a result of the bearings. I did notice that while running, in one spot between the head and block there is oil that seems to bubble in and out during compression strokes on the rear cylider. This leads me to believe it is a blown head gasket from overheating. The question I have is if anyone knows whether a blown head gasket would produce these symptoms:
Hard starting
Rough idle
Laboring after warm up (1 to 2 minutes after starting)

Any feedback is greatly appreciated.

Thank you.
CEY

thegreatrandini · Feb 23, 2005

Certainly could!!! You need to pull the head anyway!!! Why did it overheat?

CEY · Feb 23, 2005

He said he was rough mowing with it, and after it overheated, he looked at the radiator and it was plugged with fuzz.

Popstoy43 · Feb 23, 2005

Have you run the engine with the radiator cap removed. Just wondering if it is losing compression into the cooling system.
Does the oil look milky?

CEY · Feb 24, 2005

There seems to be a bit of pressure when the radiator cap is removed after idle for about a minute, I drained some oil out and there is no coolant in the oil. Coolant level is not down, at least that can noticed. Seems to be some pressure in the crank case, either due to blow-by or because the head gasket is leaking compression into the oil channel. I don't think it is blow-by, the tractor only has 671 hours.