On an oil cooler leak it's more likely to leak oil into the coolant. That part is a liquid to liquid heat exchanger. When the engine is running the oil pressure will be significantly higher then the coolant pressure. Fluid will leak from the high to the low, or from oil side into the coolant side. Then when you shut down and oil pressure goes to zero, if the engine is up to temp and the coolant under pressure, THEN it will leak the other way from coolant to oil galley.

Water or coolant in the oil typically results in something that resembles a chocolate shake. It's not really red and thin. It's more gooey or frothy. Sometimes a light tan. Transmission fluid looks red and thin. If you think it's water in the oil, pour some in a glass and let it sit a while to see if it separates.

 

http://www.passatworld.com/forums/b5-garage/462762-misfire-misfire-misfire-misfire.html

http://www.passatworld.com/forums/b5-garage/463514-low-coolant-no-coolant-wtf.html

These 3 threads all relate to the same issue, it would be much easier to follow if it was all in one thread.

Looks likely a cracked head, or leaking head-gasket.

 

Tomvw you are right and unfortunately I think I found the problem. I drained the oil first thing this morning and it is that brownish/light brownish color and thinner than engine oil should be.

Question now is, head gasket or cracked head? I always thought a head gasket would put oil in the coolant which you would see in the coolant tank. This is the other way around or are both normal to head gaskets?

 

The oil being thinner than normal doesn't seem to make much sense unless it is contaminated with fuel.
What you have reported doesn't indicate anything that could have caused this. Maybe get the oil tested.


To determine whether head-gasket or cracked head get the head crack tested, the symptoms are the same.
A head leak between an oil gallery and the cooling system will mostly put oil in the coolant.
A head leak between a combustion chamber and the cooling system will mostly put coolant in the oil.
You can get the coolant tested for these.

 

I can't seem to get my picture of the oil to upload but its chocolatey milk looking, doesn't seem to be any separation, I have some in a glass see if anything separates. However, when I smelled the oil, it smelled of fuel (confirmed by my wife - in a blind test - since my sinuses are horrible - too much info I know).

The fuel in the oil would explain the misfires and rough running, it would run fine at higher rpm (hwy speed) but stumble at idle/lower speed, I'm assuming that is because the fuel pressure goes up as speed increases? or is that incorrect?

the issue still remains of the disappearing coolant. Right now everything is drained so I can't start her up. I need to "flush" the oil if that's possible and then perhaps figure out the fuel smell?

 

I'd change that oil if you believe there could be water in there. Bearings get ruined by the water/oil emulsion, as it is corrosive and won't lubricate properly (happened to a Toyota truck I had). And being an emulsion, might not separate either.

 

Yes, a chocolate milkshake is moisture contaminated oil.

 

This may come as a complete shock (sarcasm intended) looks like head gasket is toast. Set up for a compression test, pulled fuel pump fuse, cranked it and out shot water/coolant from the #2 cylinder (possible #3 as well). I was hoping for an odds busting explanation like the oil cooler or turbo mixing but no luck. Got everything torn down and just ready to pop the head off next week after working the holiday weekend. Will post pics if I can see the gasket issue.

 

I've seen a cracked head do the same, but at this point with coolant in the oil, the motor is likely shot. I had a head gasket fail on a 3.8l V6 Ford and the bearings were toast within 1 mile. Coolant came out of the exhaust.

 

I am not as pessimistic as PZ on this, but there certainly is the possibility of serious bearing damage.

I suggest you get the head crack tested, and do a couple of quick flushes with cheap oil before adding the correct oil.

 

Finally got the head off today and this is what I found:

No glaring failures, hard to see in this picture but cylinders 2 and 3 are almost spotless so that is obviously where the coolant was going, cylinders 1 and 4 are black. Haven't checked the head yet. The only other thing of note was the gasket itself was split (evidently it is 3 separate pieces joined into one?) and it was peeling between the layers by the #4 cylinder but that could just be from the act of removing the head.

 

I suggest you get the head properly crack tested, don't rely on a visual inspection unless you find a crack.

 

What did you ever find out?

 

Cracked head, replaced the head, all is good, probably cracked after overheating due to coolant flange issue.

I had ZERO oil in the coolant like a "normal" head gasket issue, kept losing coolant into the oil.


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Glad you got it sorted

 

Bumping old thread... how is this engine running many years later? Usually milkshake in the oiling side compromises the bearings etc.

 

She's be running absolutely fine since the replacement. Had the normal oil pick up sludge issue two years after that but unrelated. Have 200K on her right now, new timing belt coming this spring.

She wasn't driven long with the issue so hopefully that helped.