Merc 350, Fresh rebuild, water in oil

[Big Boat Bay Buster]

I just fired up my freshly rebuilt 87,260. I was breaking in the cam, and noticed alot of steam and the oil turned into a milkshake! My oil level did rise which confirms its not just condensation. I had low compression and water in oil problem before which was the reason for the rebuild. I found both heads cracked which I assumed was the problem. I also bought NEW exh. manifold and risers to eliminate that as a cause. I used sealer on the head bolts and sealer on the intake manifold around the water jackets. The block and replacement heads were checked by the machine shop. Other than that, engine sounds real sweet!
After doing a search, it appears my next move is to replace the oil, pull the plugs and check for water. Drain the water, pressurize the system and listen for leaks. How does that sound? I'm not looking for a direct answer, just some food for thought and direction.
Thanks, Chris

 

[Bondo]

Re: Merc 350, Fresh rebuild, water in oil

After doing a search, it appears my next move is to replace the oil, pull the plugs and check for water. Drain the water, pressurize the system and listen for leaks. How does that sound?

Ayuh,..... You've been reading,..... Sounds like a Plan to Me......

For what it's worth,....
Leaving the sparkplugs Out, while pressure testing Isn't a Bad Thing, at All......

 

[f_inscreenname]

Re: Merc 350, Fresh rebuild, water in oil

Dollars to donuts it's the intake is leaking. Happens to the best of us.

 

[Big Boat Bay Buster]

Re: Merc 350, Fresh rebuild, water in oil

Thanks for the replys. The intake manifold is the top suspect. Main reason being is that its the only part that hasn't been reworked or replaced. There was heavy rust I/S/O the water jacket that I removed with muratic acid. The area where it mates to the head appeared good. I was told by a motorhead friend that cracks in the intake from overheating are common.My kid and I removed the milkshake oil, pulled the plugs, cranked the engine and confirmed NO water in the cylinders. At least that's a good sign. Tomorrow I'll decide whether to pressure test or dive in and remove the intake manifold. I will post my progress.
Chris

 

[Coors]

Re: Merc 350, Fresh rebuild, water in oil

No rtv, no silicone.
They don't work.
Perfect, permatex, etc does work.

 

[Big Boat Bay Buster]

Re: Merc 350, Fresh rebuild, water in oil

Commander f_inscreenname, please foward me your mailing address. I owe you a dollar and a donut.
Intake manifold sprung a leak right below the thermostat. At least its an easy fix. Will post pics later!
Chris