Water in oil, 90 Merc 3.0

[arrkerr]

Hey guys - the search isn't working on the forum and I am (or was) about to head to the lake... when I checked my oil level and found it milky.

I just had the boat in the water last weekend and it ran great. Great WOT, cruised around a bit, ran fast across the lake a few times, etc.

This was the first time in the lake since changing my impellor, which finally went the time before and caused a bit of a heat issue. My boat was lacking the "optional" (!!!) overheat buzzer, but we did notice before it got too hot (I hope).

So what are my next steps? Can I change the oil and filter and take her out today, or am I in deep trouble and my boat is done for the year?

Thanks guys.

 

[Bondo]

Re: Water in oil, 90 Merc 3.0

Ayuh,... My 1st Guess is,... It got Hotter than you thought...

Change the oil,+ Test run it for awhile, keepin' a close eye on the oil level,+ conditions....

Level is More Important than color,....
Residual amounts of Water will steam off as the motor Works,....
A Rising oil Level, means it's gaining Water as it runs,+ it's time to find out Why,...

 

[arrkerr]

Re: Water in oil, 90 Merc 3.0

Ya... it sure looks higher than it was, but I'll keep a closer eye on it. I'll also run a comrpession check. If thats fine, is the head gasket the suspect? Or is there another place water could mix with the oil?

 

[Bondo]

Re: Water in oil, 90 Merc 3.0

Or is there another place water could mix with the oil?

Cracked Blocks are common enough, especially in the Spring....'course those are Frost induced,...
Heat induced, it could be about Anywhere....

 

[arrkerr]

Re: Water in oil, 90 Merc 3.0

Would a low compression result if there is a crack in the block?

Is there a test that can be done at home, or is this a task for a shop with the ability to do a good pressure test, etc?

 

[arrkerr]

Re: Water in oil, 90 Merc 3.0

Ok, compression reveals
139 / 141 / 159 / 130

Looking under the oil cap I see milky oil all in the valves. Should I pull the valve cover and try to clean it all up, or dump some oil down in there to clean it, when changing the oil?

The book says that this can occur due to:
Water in bilge (no)
Water seeping past piston rings or valves (maybe)
Engine running cold (no, just normal)
Intake manifold leak (maybe)
Cracked casting (maybe)

For the water seeping past piston rings, it says it could be a bad manifold gasket among other things. If the water is actually leaking past piston rings, wouldn't I see some evidence of water in the cylinders... running poorly, water shooting out, etc?

If the intake was leaking, would a significant amount of water get in under normal conditions? Or do they just mean small amounts could somehow sneak in.

Ugh, not excited about a cracked casting. Do I need to pull it to test it, or is there a test the shop can do? Would the compression test reveal a cracked cylinder block, in which case it might be the cylinder head?

Thanks guys!