Mercriuser 220 diesel VM six cylinder

i have oil in the fresh waterc

i have oil in the fresh watercooling system of my marine diesel engine.4.2 litre turbo.i pulled the cooling cap off and a thick sluge was floating on top of the water.the oil cooler is salt water cooled.does any one have any idea wear it could come from?

"Hi Murray,
I take it the en

"Hi Murray,
I take it the engine is a Vetus Marine ?? Maybe with "BMW" heat exchangers ?? If so, go to the BMW section of this web site. Mercury used these engines hooked up to Bravo drives back in the late 80's. I had a 34 footer with 2 of these, never had a problem with them, had the boat 10 years !"

"your engine oil cooler is lea

"your engine oil cooler is leaking internally. Oil pressure is higher than cooling system pressure, so the oil leaks into the copper tubes.

Then when you shut the engine off, cooling system pressure pushes coolant into the crankcase.
If you sample your engine oil, you'll find it has high Sodium or Potassium depending on which type of antifreeze you run.

Fix the cooler and then do a couple flushes of the cooling system, and then a couple of oil changes.

"

"Murray,
I believe you are co

"Murray,
I believe you are correct- your oil cooler is s/w cooled. Is your engine painted BMW silver? If it is, then look for the areas of the engine that have turned gold or brown. These are where the engine has become too hot. The old silver paint was great for indicating an overheat condition. These engines had individual cylinder heads and those heads are aluminum- overheating warps them and there is no fix but to replace.
If your engine is painted Mercury Black or VM brown- sorry, can't help you. Try using a NAPA exhaust gas analyzer(this is a vial with a blue dye that you place over the open coolant filler neck and run the engine under load- if the dye turns green then you likely have a head problem. Better than randomly removing the heads.
Or you could hope an inexperienced tech accidently added oil to the coolant instead of the valve cover."

"When I first bought my Randel

"When I first bought my Randell, both motors had straight water in the cooling systems. This I promptly changed to an anti corrosion ethyl glychol mix. Aluminium cylinder heads soon corrode away in straight water. Knowing the motors, I would say one of the heads is leaking or one of the cylinder head gaskets has let go. A real pain as you have to pull the 6 heads. At least they aren't heavy !"

"BTW you'll have to grind

"BTW you'll have to grind down a ring spanner to get on to the 2 back nuts that hold the turbo onto the exhaust manifold.



One of these ???"