Water in Oil

[Scott06]

Good point on running at the dock or easy putting around. my 140 mercruiser will get a bit cloudy when putting. My small lake at 140 acres doesn’t get a lot of room for a good run. Yes I can open it up and make abut five loops and it gets plenty warmed up to burn off the moisture. It runs the 140 thermostat and yes it gets to temp when putting. Needs a good hard run to burn it off.

You could try a 160 stat in it if you dont have too much scale in the water. My old 3.0 used a 140 stat, current boat (2004 5.0) came with a 160 stat, no issues with scale

 

[Lou C]

That’s the reason why I stuck with a 160 stat on my 4.3. I tried a 140 because that’s what used to be advised for salt water but the engine took forever to warm up & there was actually condensation in the exhaust system. When I had the cyl heads off I didn’t see any real evidence of salt crystallization as has been reported either. So yes cold running will lead to some condensation under the valve covers but if you have water in the oil from an engine or exhaust problem it’s going to be much more than that….

 

[Lou C]

Did that, and the plugs look fine. I don't think there is any water in the combustion chamber. Engine sounds good when running with plenty of power.

If you have water in the oil but no water in the cyls then it can be the intake manifold gaskets which on the Vortec engines (‘96 and up) you have to be careful with; the torque spec on them is much lower (like half as much) as the older pre Vortec. Also if the intake manifold corrodes under the thermostat housing it will put water right into the cam valley & the motor oil. Sometimes on used engines there will be pitting around the water ports in the cyl heads & the manifold and when I did mine (pre Vortec) I added a bit of Permatex Aviation sealer to those areas.

 

[Scott06]

If you have water in the oil but no water in the cyls then it can be the intake manifold gaskets which on the Vortec engines (‘96 and up) you have to be careful with; the torque spec on them is much lower (like half as much) as the older pre Vortec. Also if the intake manifold corrodes under the thermostat housing it will put water right into the cam valley & the motor oil. Sometimes on used engines there will be pitting around the water ports in the cyl heads & the manifold and when I did mine (pre Vortec) I added a bit of Permatex Aviation sealer to those areas.

He pressure tested it so gasket or rot should have shown up then