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Hi everyone,

I have a Countax lawn tractor fitted with a Yanmar 2V78 V-twin diesel engine.

It has started to throw a load of steam out of the air intake when I turn the engine off and my first guess is the head gasket. I have recorded a video so if any one with knowledge of diesel engines or Yanmars can help me then that would be greatly appreciated.


The oil seems okay still, no milky oil.

Thanks in advance!

It looks low on antifreeze, how much does it use when running, also how many hours on it ?

I think you might be right on blower head gasket.

gainestruk said:

It looks low on antifreeze, how much does it use when running, also how many hours on it ?

I think you might be right on blower head gasket.

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The radiator is full and the reservoir is at the correct level. It doesn't really consume anything out of the ordinary.

It has done 480 hours

I am not that familiar with that engine. But I have worked in diesel engines. I did look up the Yanmar 2V78 engine and it looks like it is water cooled. The diesel engines that I have worked on the cooling system would over pressurize the cooling system from the engine compression would be a sign of a blown head gasket.

reynoldston said:

I am not that familiar with that engine. But I have worked in diesel engines. I did look up the Yanmar 2V78 engine and it looks like it is water cooled. The diesel engines that I have worked on the cooling system would over pressurize the cooling system from the engine compression would be a sign of a blown head gasket.

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Yes and I have had one just leak down side of engine, on a large diesel we would take a piece of white paper against the exhaust outlet run engine up to about 1500 rpm and see if we got much moisture, I have seen a few steaming out exhaust at idle.

If you are not loosing any antifreeze you might be ok, I would run an oil sample and see if you have any antifreeze show up in oil, if you do it could be head gasket to cracked cylinder, I don't know if that engine uses liners or bored block.

I would test by pressurizing the cooling system, or a compression test, or a test kit. Sounds workable right now; later could be more expensive.