Bad Exhaust Manifold

[jcupo6]

I have a 1973 mercruiser 3.0 140hp engine. Water is in my oil. There was a little bit of water in cylinder #4. Change the head gasket, didn't seen any obvious cracks in the head. Compression is 1-130, 2-130, 4-130, 4-120 is this average? Seemed to have less water in the oil with the thermostat out. Could a bad exhaust manifold cause the water, and would that explain why it seemed to get worse with the thermostat?

Thanks for the help!

 

[Maclin]

Re: Bad Exhaust Manifold

Water in cylinders is usually from bad exhaustmanifold/riser or related gasketing.

Water in oil is usually from cracked internal cooling passages in the block.

Regarding less water in the oil with the thermostat out, there would be more pressure in the cooling passages in the block with the thermostat in than with it removed.

Time to pressure test the cooling system.

135 psi would be good compression for that engine. 120 is tired but not too bad yet. The numbers also depend on how the check was done, warm engine or not, "wet" or not, with all sparkplugs out and carb wide open and good battery and healthy starter.