Water in oil. Can't find the source...

[AdellAdam]

1986 MerCruiser 140. I bought the boat with water in the oil. I took the head off and tore the block down. The head gasket was fine. I couldn't visually see any cracks in the block or head. I put the head back on with the original gasket (but left pistons, crank, cam out) and filled it up with acetone. I sealed the system off and applied some air pressure to it to see if i could find the leak. I had it up to 50psi but I can't even smell acetone coming from anywhere. I can't see any leaks and I even used a spray bottle with soapy water and nothing bubbled. There was way too much water in the oil for it to be the manifold. The guy before me noticed the water in the oil and changed the oil. Then he tried it again just on the hose and it filled up with water again. When I drained the oil there was about a gallon of water and a gallon of milk that came out. Short of heating the block up in an oven what can I do to find the source of this water leak? I'm getting really irritated with this. Can a maifold leak cause that much water?

 

[EddiePetty]

Re: Water in oil. Can't find the source...

...do the same hydro tests to your exhaust manifold and riser.

 

[NHGuy]

Re: Water in oil. Can't find the source...

You test the exhaust manifold water passages by blocking them off and applying air at 40 psi, then dunk it and check for bubbles. That's the logical step, you should do that next.

 

[AdellAdam]

Re: Water in oil. Can't find the source...

I'm curious as to how that could cause that much of a leak into the oil. All signs point to the block being cracked, but I will check the manifold. If it is the manifold I'll be PO'd cuz I just tore down the block for nothing!

 

[AdellAdam]

Re: Water in oil. Can't find the source...

Well, the manifold does not leak. Now what? I guess I'll just drop in a 4.3L and save myself the trouble...

 

[AdellAdam]

Re: Water in oil. Can't find the source...

I reassembled the engine, dropped it back in and ran it. No water in the oil. I had it running about 10-15 minutes on the muffs. It got warm and the water hoses were warm so it was up to opperating temp (i think). So I have no idea how water got in the oil to begin with. The guy who sold it to me pulled it out of storage and said he ran it and found water in the oil. His mechanic changed the oil and ran it and there was water in the oil. I have no idea what happened, but it seems to be okay now...

 

[Don S]

Re: Water in oil. Can't find the source...

Very few engines with cracked blocks leak on muffs running in the driveway.
Put the boat in the water and run it if you want to see if it leaks, or, you could block of the water hoses going to the exhaust exhaust, drain the block, and pressure test the block with air and see if it leaks.

 

[AdellAdam]

Re: Water in oil. Can't find the source...

I said in the first post that I pressure tested the block with acetone and 50psi air pressure and nothing leaked. I blocked off the tube running to the manifold and I used the water inlet pipe to supply the air pressure. I know the whole block got pressureized because the hose between the water pump and the thermostat housing got hard as a rock. I couldn't see anything or even smell any acetone anywhere. This whole thing baffles me. I'll be running it in the lake tomorrow to see what it does. I'll be so happy if it runs fine tomorrow, but I'm not getting my hopes too high.