White smoke from Yanmar 2GM

[Modulation]

Developed over the end of last season. New prop on boat (same size as old) and she motors very well so I don't think it's to do with overloading. The manual gives a long list of what it might be but what are the more likely causes and what should I look for first?
Incidentally, it vanishes about a metre from the exhaust so I think it's nearly all water vapou.r
Did a search on this but nothing came up - only stuff on grey or black smoke

 

[atol]

white smoke generally denotes water in the fuel.
check your water seperator,or could be cylinder head or cracked piston liner

 

[misterg]

... or it could just be condensation in the colder weather...

Andy

 

[tinkicker0]

Developed over the end of last season. New prop on boat (same size as old) and she motors very well so I don't think it's to do with overloading. The manual gives a long list of what it might be but what are the more likely causes and what should I look for first?
Incidentally, it vanishes about a metre from the exhaust so I think it's nearly all water vapou.r
Did a search on this but nothing came up - only stuff on grey or black smoke

White smoke is unburned fuel.

Steam on the other hand is condensed water vapour from the combustion process getting in either by internal leak or via the fuel or intake systems

 

[pagoda]

White smoke is unburned fuel.

Steam on the other hand is condensed water vapour from the combustion process getting in either by internal leak or via the fuel or intake systems

2GMs are direct cooled. Our 3GM occasionally generates a little "steam" in cold conditions <8C ? - depending on ambient humidity. It vanishes as you said , within a metre? - recall cars running on cold mornings... diesels included? The hyrdocarbon combustion process produces ultimately CO2 and water.. Whether you see the water depends on temperature & humidity.

If you think it's unburned fuel - stick a small mirror or similar in the "smoke" and check the condensate. Oil or water?
Water drawn into combustion chambers would probably make the engine run very roughly at the least. ( at the very worst you could suck in enough to crack the block!!!)

 

[charles_reed]

2GMs are either raw-water or indirect cooled.

One of their typical faults is of the coolant getting past the head gasket, into (usually # 2) a cylinder.
If a raw-water cooled engine, apart from a white exhaust there is no other sign - with indirect cooling there is a drop in the coolant level, due to the overflow being pressurised on the combustion stroke and depleted on the induction stroke.
I had a 2GM that ran for 3 years with that problem with no apparent drop in power.

 

[BlueSkyNick]

White smoke is unburned fuel.

Steam on the other hand is condensed water vapour from the combustion process getting in either by internal leak or via the fuel or intake systems

I thought black smoke was unburned fuel