water in oil

appears to be leak from radiator system into engine oil. what kind of fix can prevent this

The possibilities are:

1. "Leaking head gasket." Pull the heads and check for leaking gaskets. If no leaks from the head gaskets are found, go to step 2. **If you're really lucky, and have a V-6 or V-8, maybe you'll only need to seal the intake manifold to head area.

2. "Cracked cylinder." This is a major repair job. Have you overheated your engine recently? If you or someone had grossly overheated your engine and ran the radiator dry it's possible to develop a cracked cylinder. The fix would require a complete engine disassembly and having a cylinder sleeve installed. It is possible for someone to do the same job in-frame with a portable boring bar, but such people to do that job can only be found in the largest of cities. I know....I used to do that kind of work too. You'd still have to pull the pistons to inspect the cylinder walls.

Can you give us a bit more feedback as to what lead up to this problem?

There is one more possibility if you have an HD with the heavy duty towing package - the oil cooler could be cracked inside your radiator, but you would probably be able to see oil on top of your coolant in the radiator.

Hope this helps.

In reply to problem development, I noticed that my radiator overflow tank was always a bit low. I had two different mechanic shops check radiator thinking it was leaking. Both said no leak. There were no instrumentation indications of either high temperatures or any other instrumentation except the check engine light would occasionally come on. Now, I have had a slight leak in oil system for long time, but have always keep up with it by regular oil maintenance replacement. Then I noticed that my oil losses had stopped for no reason. Now it is clear that water is getting mixed in with the oil because the oil system is overflowing and oil quality clearly indicates oil/water mix.

Okay, in that case you probably DON'T have a cracked cylinder, but probably DO have a leak between the intake manifold and a cylinder head. If the oil is showing-up in the radiator too, then it could be what GMC Tech mentioned OR a leaking head gasket. In any case, at least the intake manifold has to come-off for that first step look. If you find nothing there in the way of water draining down into the center of the engine, then next the heads have to come-off(which means that the exhaust manifold comes loose first). Before re-installing the heads, make sure you know what the torque values are and use the proper bolt tightening sequence so as not to warp the heads. Buy a repair manual (cheap...about $20) from the auto parts store that pertains to your particular vehicle. If yours is a newer vehicle with all that spagetti wiring and hoses for the fuel emission control, tag each one with a small piece of masking tape so that you know where each line, hose, and wiring connection came from. i.e. #1 hose connects to #1 fitting. #2 hose connects to #2 fitting....and so forth. This is guaranteed to be a learning experience for you, but you'll save money doing it yourself. Have lots of rags handy.