Mercruiser 3.0 Rebuild or not

[markhodges78]

I have a mercruiser 3.0 I have been fighting issues with idling . I replaced the carb didnt fix the problem then I noticed that I had milky oil puddled on valve cover so I assumed I had a cracked block. I removed the elbow and found that the elbow is bad so that may be the problem with the water in oil right ? now moving on to the oil on valve cover I did a compression test and got 130 on all cylinders so I did a leak down test on all cylinders on got a 10-14 psi drop with pistons at tdc and it sounds like alot of air coming from the oil fill if I hold finger over the breather hose it will blow the fill cap off is this normal. pictures are attached... should I replace the intake and elbow and roll with it or should I tare down and rebuild ?


Thanks Mark

 

[Bondo]

Ayuh,..... I'd replace the exhaust, 'n Go Boatin',......

The milkyness in the valve cover is probably condensation,.....

 

[markhodges78]

Ayuh,..... I'd replace the exhaust, 'n Go Boatin',......

The milkyness in the valve cover is probably condensation,.....

It wasn't just in the valve cover.... I noticed the milky oil on top of valve cover making me think blow by because oil was on top the entire oil pan was full of milky oil so I changed the oil and took it out the next day and it was milky after 1 hour run... but I believe that was because of bad elbow and manifold which I will replace... but now my concern is the blow by issue.... are is it an issue ?

 

[Scott06]

It wasn't just in the valve cover.... I noticed the milky oil on top of valve cover making me think blow by because oil was on top the entire oil pan was full of milky oil so I changed the oil and took it out the next day and it was milky after 1 hour run... but I believe that was because of bad elbow and manifold which I will replace... but now my concern is the blow by issue.... are is it an issue ?

You may have to change the oil 3 times or so to get any milk cleaned out. Buy the cheapest oil you can put only 3 qts in, run it at the dock or on the muffs, keep changing the oil and filter until it stays clean.

 

[wshekar]

I would not think about a rebuild yet. The compression values are fine. Replace exhaust and replace oil several time as previously suggested.

 

[Scott Danforth]

I would never rebuild a 3.0.

to rebuild one will cost your $1800

to buy a good running 3.0 in a rotten boat is only $300 +/-200

i agree with everyone above, run it.