535i: Oily coolant in intake duct around throttle body

[Dash01]

Is this consistent with a head gasket problem?

How would oily coolant get there?

[wiggywigton]

If you know that you have a blown head gasket that is allowing oil into the coolant system then there is a possibility that your TB gasket is leaking coolant (oily in your case) into the intake passage. There normally is an oily deposit on higher mileage vehicles that builds up over the years. THis is normal and should be cleaned with a carb cleaner.
I am assuming that your car is running rough. YOu might have jump to conclusion to think that it is a blown head gasket but it might just be the TB gasket. I am assuming that you checked the obvious, the radiator, to see if there is oil in the coolant?!?!?

[Dash01]

I drained the rad. water into a bucket, and the water shows no oil.

I now think the oily water in the throttle body was the normal oil that collects there in an old car, plus some coolant.

But, how would the coolant get there?

[genphreak]

I drained the rad. water into a bucket, and the water shows no oil.

I now think the oily water in the throttle body was the normal oil that collects there in an old car, plus some coolant.

But, how would the coolant get there?

Get an oil sample from your crankcase and get a test. It is the only way to know, other than pulling the head and inspecting- even then it might be a small crack requiring hot-tanking to find it... so you might consider finding a second hand head as it will make replacing the current one faster (not waiting for the shop to machine and rebuild it); it can help prevent the chance of a crack going undetected.

To answer your question, I would expect coolant is seeping into the oil at the top of the engine, boiling off in the head and being recycled by the EGR system (along with the CO and other nasties) back into the intake via the vent pipe that goes to the main intake boot, just before the Throttle Body. All these pipes are cooler so it will condense a little. Because it contaminates the oil before doing this, there will be traces of ethylene glycol in the coolant- if this is happening.

[Dash01]

Thanks for the insight and suggestions.

This problem came about last week driving down the road, per normal.

Suddenly, the temp gauge went to the edge of the hot zone, so I turned off the AC and temp went back to normal momentarily. Then, temp went back up to edge of hot zone, and the low oil pressure indicator came on.

The engine shut down by itself as I was pulling into a parking lot, so rolled to a stop. Steam appeared around the heat deflector flap around the exhaust manifold. Radiator runoff had oil sheen on it.

I called AAA and got flat-bedded home.

The HG has over 150K on it.

I'd previously experienced the common oil pressure light issue common among 535i cars, but wiping off the oil pressure sensor cured it. I suspect the oil pressure sensor still needs replacement, but that does not mean the oil pressure is necessarily OK--could still be the pump.

The car starts but has low oil pressure indicator, so shut down after a few seconds.

The oil filler cap has some thick milk chocolate-colored oil goo on it, which I suspect is the result of mixing oil and coolant.

Further insights or suggestions?

[slupregime]

popped head gaket