Water in oil, but not in cylinders

My 1990 Mercruiser 3.0 has water in the oil. Its like a milkshake, and the level is up about an inch on the dipstick over where I usually keep it. It had overheated due to impellor failure and lack of a warning buzzer (and lack of me paying attention).

The plugs don't show signs of moisture.

I've read the manual and I know what the possibilities are, but what I'm wondering is what is ruled out due to the fact that the cylinders aren't wet. Seems like that rules out a leaking intake, and maybe exhaust, since cracks in those wouldn't allow oil to mix with water unless the cylinders got wet in the process. Does that make sense? Does it also rule out the possibility of a bad head gasket?

Re: Water in oil, but not in cylinders

Ayuh,... Drain the block, isolate the cooling passages,+ Pressure test it with Air,...
You'll Hear where it's leaking, just follow the Sound...

Btw,.... What's with the New thread,..??
I know you've got Another 1 going about this Exact Same problem.... I posted on it...

Re: Water in oil, but not in cylinders

Sorry, didn't mean to dual post... the other one was a general "what could be wrong", this one was just a quick question about if the head gasket would get water in the oil but not the cylinders.

Really appreciate your help bond-o, with out you guys I'd be lost. Sure am learning about every aspect of boats... seems like as soon as I fix one thing another thing goes . By next year I'll be a certified mecanic (or maniac, whichever comes first ).

Re: Water in oil, but not in cylinders

By next year I'll be a certified mecanic (or maniac, whichever comes first ).

Click to expand...

Ayuh,... I was born a Maineiac, but had the Learn to be a Mechanic,.....

Re: Water in oil, but not in cylinders

I know a month or so ago I saw the process for pressure testing, but for the life of me I can't find it. I thought it might have been in the adults only section, or maybe in the manual somewhere...

Any clue where I saw it...?

Re: Water in oil, but not in cylinders

I posted the previous, Please post what you find, I'm curious to know what it is. This is my first I/O and not sure what to do.

Re: Water in oil, but not in cylinders

Come to think of it, what I read before was how to test for leaky cylinders I believe. Put it at TDC adn listen for leaks from the crankcase and exhaust and intake.

Wouldn't I want to be putting some air in the crankcase, like via the dipstick tube, and listening for leaks in the intake, exhaust, and spak plug holes? If the block is cracked, I would think I might have to rotate the engine a few times to pick up a leak. And how much PSI can I throw at the crankcase with out damaging anything? I'd have to plug the oil cap as well.

Re: Water in oil, but not in cylinders

Wouldn't I want to be putting some air in the crankcase,

Click to expand...

No,.. The Cooling system,... about 12/ 15psi...

Re: Water in oil, but not in cylinders

Which passages should I isolate, and where should I add air? The water mixes back with the exhaust in the elbow pipe that connects to the exhaust manifold I believe. I pulled the elbow and I see what I think are the water passages on the sides, and the exhaust is the center. That gasket was blown, and water was leaking around it. I wonder... could the water have managed to reach the oil due to that gasket being blown?

At any rate, if I plug those passages somehow, I would think I should remove the hose from the water circulating pump, and add air there? Or cap it off too and add air through the manifold drain plug, which might be easier to stick my air compressor hose in.