I posted an article last month about white smoke coming from my 3HM35F Yanmar engine and promised to update the forum after it went in to be fixed. To recap, we had white smoke from the engine. It got progressively worse under load from say 2100rpm onwards. The engine did not overheat, there was no loss of power and no loss of coolant. However, you could see what looked like a stream of unburnt fuel coming out of the (wet) exhaust. When our engine guy first tested it, he said he couldn't find anything wrong so he asked another Yanmar engineer who said it would be a small crack in the head gasket. The head gasket was replaced and the injectors cleaned. When I rang to check on the progress, the engine guy said the machinist confirmed that the head gasket had blown in two areas. I was relieved as the research I had conducted (see below) listed numerous potential causes. We used the boat yesterday (the engine guy didn't have time to test it under load and we wanted to use it over the long weekend) and (you guessed it) the white smoke problem is still there - exactly as it has been prior to the replacement of the head gasket (although the stream of unburnt fuel has now gone). My previous research has produced numerous causes for white smoke including: a) blown head gasket b) timing c) bad fuel d) bent rod e) loose hoses f) burnt valve seats g) water in the fuel h) fuel cetane rating too low I'm going to try a cetane additive to eliminate (h). If anyone has any other ideas I would greatly appreciate hearing them.
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Steam?
Hi David, Where are you located and in what kinds of weather conditions and water temps are you motoring? We have the same engine in our 37.5. Hot exhaust water hits cool damp air sometimes on our boat creating steam. Other times we get nothing. May not be the cause, but its just a thought. Gary Wyngarden S/V Wanderlust H37.5
Hi David, Where are you located and in what kinds of weather conditions and water temps are you motoring? We have the same engine in our 37.5. Hot exhaust water hits cool damp air sometimes on our boat creating steam. Other times we get nothing. May not be the cause, but its just a thought. Gary Wyngarden S/V Wanderlust H37.5
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