After three years without a problem our 3GM30F began to overheat while mortorsailing on the third day of a run down the coast from Cape Fear to Ft. Pierce. No noticable loss of power or other obvious symptoms other than;
- Slight loss of coolant, mabe 8 oz. with no sign of leakage.
- Lube oil in the freshwater coolant, a little at first, then more and more.
We shut down each time the alarm went off and did not overheat the engine - no scorched paint, hot smells or painful to the touch engine surfaces.
Once at Ft. Pierce we pulled the head and found signs of a leaking head gasket around the center #2 cylinder. And, steam cavitation pitting on the head’s combustion chamber and exterior surface of the injector! It appears that there has probably been some head gasket leakage here for quite a while - loss of compression may account for the somewhat difficult starting when cold we have been having?
How would oil be getting into the cooling system from this location? Or may we be faced with two unrelated problems-- a leaking head gasket, plus a leak of oil into the coolant from some other location?
How much pitting on combustion chamber surfaces is tolerable before performance is affected?
Now that the head is off, what other potential problems should we be looking for or preventative maintenance items taken care of before fitting the new gasket and putting her back together and hoping that the problems have been fixed?
I cross-posted this to the yanmarhelp.com forum but don’t yet know how active it is.
Thanks for any suggestions,
PS. Apart from and despite the engine problem we had a fine run offshore from Cape Fear to Ft. Pierce, Four and a half days and four nights close reaching with starry nnights and lots of dolphins accompanying us from time to time. Wind veered the last day and a half so we did some hard motorsailing into headwinds and swell to make Ft. Pierce before nightfall and with favorable tide in the inlet.
After we get the engine back together we are heading across Okeechobee to the Gulf Coast for a while then to the Bahamas. Anyone have a suggestion for a good do-it-yourself tolerant yard in the Ft. Myers - Sarasota vicinity whwew I can haul and fit a new rudder? Or a cheap place to leave Itchen for a couple of weeks while we take care of things at home?