Yanmar smoking/racing after 2 hours

[carl gamble]

This past weekend, we motor our Hunter 310 for about 1.5-2 hours and then huge plumes of balck smoke came out of the exhaust and the engine started to race. Sut down the engine and could not get it started over the next 2 hours.

Next morning, checked oil, coolant and transmission fluid levels and all looked fine. Started engine just fine.

The engine never really seemed to get hot at least it was not hot down below right after we turned it off.

Any ideas on where to start looking?

 

[Gary Fisher]

Run away Yanmar

Carl,

2 thinks come to mind, (1) Smell your oil, it may be mixed with diesel fuel that would cause foaming
and could cause a runaway. Happened to me a couple of years ago on my 28.5. We found the cause
was a leaking fuel pump diaphragm that was mixing diesel into the oil. (2) check for water vapor
in your fuel, when water gets into the injection pump it causes odd things like smoke and the no start
situation, check the oring on your fuel cap, as if it's cracked or bad will let water into your fuel. Hope this helps. Gary Fisher

 

[Steve Dion]

Recent oil change?

Carl:

Have you had a recent oil change? If the crankcase was overfilled this is a common problem for a run-away engine.