Re: 2.5l mercruiser head gasket
I don't know whether one could be related to the other but in my past experience it is worth the time to check for a leak in the exhaust system any time there is overheating before it causes more problems. Overheating could have been the cause of the problem with the head gasket instead of the head gasket being the cause of the overheating.
My friend, father and I learned the hard way that the exhaust system in a boat handles both the exhaust gas and water after it cools the block. My dad is an auto mechanic with over 30 years experience (and running his own shop) and wasn't aware of that when he helped swap a motor in the friend's boat and we had trouble with an exhaust bolt during the swap. He said to not worry about it. On a car it wouldn't be a problem (well, at least it is something you can live with, just don't let an emissions inspector find it!) but apparently it is on a boat. The boat didn't even need a new motor so we caused even more problems doing a fix that didn't need to be done. He paid a marine 'mechanic' to check the lower unit when it started making noise and $150 later he said it was the motor and the lower unit was fine. Of course AFTER all the trouble of switching it all out the noise was still there and it was the gimbal bearing and u-joints.
Anyway, some water was leaking in with the exhaust and it basically superheated as soon as it hit the hot gasses, turned to steam, caused the motor to overheat and cracked the exhaust manifold. We got lucky that the overheating didn't cause any other problems because overheating can kill a motor.
The only positive to the mess was that we found a great marine mechanic that we go to for anything we aren't 100% sure about now and he took care of some other adjustments at no charge when he replaced the manifold. We also got away with using the manifold off of the old motor since it was fine. The motor we put in had come out of a boat which had been run into and totaled while on the trailer so we got everything for $200 and he scrapped the rest of the boat. And we have a spare motor and all the brackets and accessories (minus the exhaust manifold) now. Man that was an expensive and frustrating year but it could have been a lot worse.
Anyway, I don't know if any of that made sense but I would probably check it out or have it checked out just to be safe.
