This past Friday after motoring in very light air for several hours the diesel just stopped! Both oil and temperature were normal, usually checked every 15 to 20 minutes. Also both were checked before starting that morning.

I jumped down to open engine compartment expecting to find a fuel problem, but Racor bowl was full and clear. The expansion tank was opened and it was frothy. After allowing to cool, the expansion tank had ample water; oil showed normal and no sign of water. The only other factor was that for the last few days there was soot around the compartment. The engine has about 3600 hours and is original to the boat an Allied 39 built in 1970.

My guesses are: head gasket failure, water cooled exhaust manifold, or O ring failure around wet sleeve cylinders.

Any input would be appreciated. Thanks.

Eddie