78 3.0 mercruiser overheated ?

[gearhead79]

I reacently perchased a 78 fourwins with a 140 mercruiser. Was told that the head gasget was bad ,also that it had been replaced and went bad recently after that. Which lead me to believe that it had overheated. Quick inspection of the motor showed deffinate signs of water in the oil. So is possible is the gasget. Hopefully not more like cracked or warped head or possible leak in the water jackets in the block. In any case gonna tear it down least to the block to have look see go from there. But what im curious about is the common causes of overheating for that particualr make of engine. So far i considered the impeller the water pump. Is the impeller the most common or is there more to consider.

 

[Rocky_Road]

Re: 78 3.0 mercruiser overheated ?

You are right about the raw water (impeller) pump being the most common culprit.

But another possibility is that the belt broke, and the owner tried to drive it back to the dock. This engine has a water pump behind the pulley...and without the belt, the engine will heat up pretty quick!

Just two possibilities....

Good luck!