Yan Marr burning white smoke but engine seems to run fine

[waynepoynter]

I have a young YanMar engine on a beneteau 473 sailboat and I haven’t driven the boat in a while. today I tried to take the boat out and I was billowing white smoke more the faster I read the engine, but no loss of power.

The internal cooling reservoir was dry as well as the tank. I put coolant in the tank, but only a small amount would fill it up. Restarted the engine same thing.

Injectors are one issue and maybe a head gasket issue, any other ideas.?

 

[ChromeDome]

If the white smoke is steam it must come from heat.
Did the engine feel very hot?

Time to check coolant flow (thermostat) and sea water supply (impeller pump) and, despite being young, the exhaust elbow?

If not steam you may be right about head gasket. How does the engine oil look? Replaced recently? Level ok?

 

[Spirit (of Glenans)]

Check that the raw water inlet is not blocked.
If your filter is connected do a seacock in the hull close the seacock, detach the hose from it, attach a length of spare hose that will terminate above the waterline then open the seacock and insert a suitable rod, drain snake, length of wire clothes hanger, whatever, to push out the blockage.
If your raw water supply is through a seacock integral to a saildrive, particularly a Volvo Penta one, you will need to attach the length of spare hose as above, but you will not be able to rod it, instead apply air pressure either from your lungs or a dinghy pump. In my case I found lung power to be sufficient to remove the fragments of mussel shell that I had accidentally rammed into the inlet while clearing out the saildrive leg with a length of metal bar.

 

[vyv_cox]

The first thing to establish is whether it is smoke or steam. Smoke hangs around for ages until blown away whereas steam disappears relatively quickly. Smoke sometimes will be emitted from an engine that has not run for some time because fuel has dripped from an injector while stationary, or due to overfuelling when trying to start it, but this soon ceases. How long did you run the engine?

 

[Dellquay13]

The disappearance of coolant is concerning. Does the engine oil look like like dirty brown custard?

 

[DickB]

Steam is due to raw water volume insufficient to cool exhaust. Check the rubber exhaust pipe just after the exhaust elbow. It shouldnt be very hot. The interesting thing is that to col the engine requires little water so the engine temperature may be fine (80 deg), but may not be enough to cool the exhaust.

 

[ChromeDome]

The disappearance of coolant is concerning. Does the engine oil look like like dirty brown custard?

There may actually be coolant in the oil even if looks normal. The mayo feature rakes quite a lot of water to build.

 

[Dellquay13]

If it is a newish Yanmar, will the engine be freshwater cooled, with raw water cooling for the exhaust?

 

[Iliade]

Cracked block from freezing during the cold spell before Christmas?

Unburnt diesel 'white smoke' reeks of fuel. Steam smells of hot ironing. Hold a white cloth against the exhaust to get a quick decision as to whether it is unburnt fuel (sadly unlikely) or steam.

 

[waynepoynter]

If the white smoke is steam it must come from heat.
Did the engine feel very hot?

Time to check coolant flow (thermostat) and sea water supply (impeller pump) and, despite being young, the exhaust elbow?

If not steam you may be right about head gasket. How does the engine oil look? Replaced recently? Level ok?

The engine is not overheating.

If it is a newish Yanmar, will the engine be freshwater cooled, with raw water cooling for the exhaust?

Sorry auto correct changed it to young, 1,700 hours