Cracked Head

[pontiacta95]

I have a 1979 Mercury Thunderbolt 70HP. It is a three cylinder engine and the top piston sleeve has a crack right next to the spark plug hole. Is there a way of fixing this like aluminum welding or do i have to get a hole new power head?

Thanks!!!

 

[bgbass.1]

Re: Cracked Head

you can try using jb weld it may work its better than buying a new head

 

[Chris1956]

Re: Cracked Head

That crack is in the water jacket cover, not the cylinder head. You can replace the cover or smear it with some silicone, if the crack is not too wide. The water pressure should be less than 5 PSI at that place.

 

[emckelvy]

Re: Cracked Head

The crack may or may not be in the cylinder block water jacket cover. He says it's in the block. I've seen these crack the cylinder before from overheating. The impeller fails at speed, the engine heats up catastrophically, and the block cracks at the hottest point (#1 cylinder).

If you have the block cover removed and the block itself is cracked, it's non-repairable. The block is made of a special alum alloy which is extremely hard to weld.

A friend of mine had his welded up and it held for a while, then blew out. Of course at that point, the impeller was new so it pumped all kinds of water into the motor and ruined it.

Best thing you can do at this point is teardown and inspect the remaining parts to see if it'd be worth getting another block. If the crankshaft and rods are shot it's probably not worth fixing.

HTH.........ed