ThetaTau87

I replaced my upper radiator hose due to a small tear at the clamp on the engine side. When I opened up the coolant reservoir I found a milkshake typical of oil contaminated coolant.

The car runs great. The oil is clean with no signs of any coolant in it. My coolant temps are right where they should be. The only symptom is oil consumption (about 1.5 quarts in 750 miles.) I just bought this car at the end of June. I checked the oil when I inspected the car, but not the coolant. I don't know if this is a new problem or has been going on for a while.

I'm wondering how the oil is getting into the coolant. Is the head gasket the only place where oil and coolant could get mixed? Is there an oil/coolant heat exchanger or anything else that could fail/leak and cause pressurized oil to leak into the coolant but not allow coolant contamination in the other direction?

Bilal928S4

Oil cooler.

Mrmerlin

check your radiator see if there are hoses attached to the left side of the radiator,
if so then possibly the cooler has failed if not then its probably a headgasket.

also a possibility someone has poured oil into the coolant bottle,
but with the oil loss being reported its probably not that

ThetaTau87

There are oil lines going to/from the LH end tank of my radiator.

Next question is how do I diagnose if the oil cooler in the rad or the head gasket is leaking?

I'm thinking of trying to pressure test the oil cooler to determine if the leak is there. I'm guessing it is with as well as the engine runs. I've never seen a bad head gasket on an engine that didn't show any other symptoms other than oil in the coolant.

j.kenzie@sbcglobal.net

Hi,
This makes me remember one of my dumber moments. I drained the oil in my lawn mower, and needed a place to put the cup or so of oil. I dumped it into a windshield washer bottle and stuck it in the corner. Many months later, my car needed washer fluid. I dumped about half a cup of oil into the washer reservoir before I saw what I did.
Strange things can happen. I hope for you the best.
Dave

ThetaTau87

I see that 928 Int. has the radiator end tanks available separately.

http://www.mailordercentral.com/928i...106%20041%2001

Is the cooler just a tube inside the end tank? I'm hoping I don't have to replace the entire radiator to fix a leaking oil cooler if that turns out to be the problem.

j.kenzie@sbcglobal.net

The cooler looks like a mini-radiator that fits in the end tank. I'm sure you can buy it separately.
Dave

hans14914

I have a radiator with a bad end tank (but had a good cooler in it). It has some sealant on the tank seam from the previous owners attempt to seal without replacing the tank. I have been using it as a mockup for some parts, but if you cant find a tank elsewhere, I could extract that cooler.

Rob Edwards

Not just a tube-

Post 1 in this thread shows the fins of the oil cooler inside an end tank- not the best pic but gives an idea.

https://rennlist.com/forums/928-foru...-pics-wow.html

Mark Anderson

Tanks are easy to come by but the cooler is not. I know we don't sell them and I've never seen them available anywhere

Mrmerlin

to diagnose the oil cooler failure you would remove the lines form the cooler and connect them then you would drain the coolant system and flush it out, then refill with some water,
and run the engine this to see if oil is still getting into the coolant ,
if this is happening then you have either a bad head gasket or a cracked head

GregBBRD

An '89 has the "updated" heads. Not likely to crack. 90% of the time, this is a "cooler" problem.

Replace the cooler, clean the system up, and hope for the best. You will get oil "sludge" from the radiator and the corners of the cooling system, for quite some time....so don't panic when you "see" oil in the overflow tank, when you are done. You will be "removing" this sludge for a few weeks.

If Hans has a "loose" cooler....jump on it....and send him a few bottles of his favorite whiskey. Good coolers are going to get to be very rare, now that there are no new radiators available from Behr.

Mrmerlin

Thanks Greg for the clarification I forgot about the Gt heads

polecat702

I'm glad I bought a new radiator from Behr last year, and kept the old radiator.

Bonton

I went through this whole saga. hand wringing, thinking it could be the head gasket. This opinion and than on the forums but also helpful information. I replaced the radiator with an incredible aluminum one from 928 Motorsports, it is a work of art and solved the problem.