Mercruiser 120 Water in Oil Mercruiser - FelPro - Sierra Gaskets

[mlackore]

I have a Mercruiser 2.5L (AKA 120) 1984 model with water contamination in the engine oil. I have gone through the standard, emergency motor-saving steps.

Considering the rough idle this boat exhibits, I suspect a head gasket, cracked head, or cracked block. I have a couple of questions before I dig in.

First question: In preparation for the project, I am shopping for some gaskets. What are some opinions regarding the Fel-Pro, Sierra, OEM, or other gaskets?

Second question: Before I proceed to dig deep into this old iron duke, I plan to do a compression test. Will this positively diagnose whether I have a cracked head, block or blown head gasket?


Thanks guys.

 

[Bondo]

Re: Mercruiser 120 Water in Oil Mercruiser - FelPro - Sierra Gaskets

Second question: Before I proceed to dig deep into this old iron duke, I plan to do a compression test. Will this positively diagnose whether I have a cracked head, block or blown head gasket?

Ayuh,... It ain't an Iron Duke....
That's a 2.5l Pontiac based corporate motor,... Used by alota Hot Rodders...

Yer's is a Chevy...

A compression test will tell ya if the headgasket is gone,...
A cooling passage pressure test usually shows ya where the cracks are...