Spence73

I know what this means but I need to hear it from the experts because JUST MAYBE there is a coolant reservoir or a cross connect that just MIGHT bleed oil into the coolant.

The overflow tank has a slight drip, I noticed today, that is a milky white and smells of oil. I immediately checked the oil filler cap and the oil inside the engine is nice and clean.

Is there ANYTHING else besides the head gasket that could explain this?

TIA!

Oh, It's a 2007 530i with 156K

BimmerFan52

I assume you have not changed coolant brands or topped off the system with anything other than BMW coolant, although while mixing types might cause precipitate it wouldn't add the smell of oil.

If you have another car to drive I wouldn't drive the 530 until you get to the bottom of the matter as if there is water in the oil it will dramatically accelerate engine wear. Even if you can't see "milk" or smell the antifreeze you may still want to dash a sample of oil off to a testing lab to make sure, as catching it early is the key.

If indeed there is no water in the oil then another possibility is transmission fluid if you have an automatic. The transmission fluid cooler lines enter and exit the radiator and you can start by examining the where the lines enter the radiator to see if you see any leaking. It wouldn't hurt to also open the radiator drain valve for just a few second and see if the concentration of contaminant is higher or lower at the bottom of the radiator.

Also, the pressure of the coolant system increases after the car is shut down. The transmission lines may force transmission fluid into the coolant while the engine is running but water may also be forced into the transmission fluid after the engine is shut down. If this is happening the transmission will take a beating and you will need to address it quickly.

turboawd

good points mentioned above.

has the car ever overheated?

if you cant find anything wrong, i'd probably do a coolant system pressure test. one when cold to see if pressure drops, and another when running the car to see if the pressure gets too high, which could indicate exhaust is pushing into coolant system.

assuming the radiator is not the issue, then the next thing would probably be headgasket.

Redtwin

Is the car an automatic? Transmission cooler may have a leak/fault allowing transmission fluid to mix with the coolant.

Of course that could possibly mean coolant has entered transmission so don't drive it until you find the prob.

Spence73

Good points... no the car has not run hot (thank goodness).

Yes, it is an automatic.

I can't tell if the oil mixture in the water is indeed the engine oil or tranny fluid, it's mixed too well.

Probably have it pressure tested today and I have no idea where to send a sample to.

Any suggestions?

Thanks!!

pcy

As others suggested, trans fluid and coolant go thru the radiator, so that's one possibility.

Other possibility is that the oil and coolant get close to each other in the oil-cooler.

If I were you, I'd send the coolant sample to lab. If the lab results come back with trans fluid, then the first scenario is the likely cause. If the lab results come back with oil residue in the coolant, then oil cooler should be inspected.

Spence73

Took the car to a local Bimmer Dr. nearby and checked in the valve cover and opened the expansion tank slightly and it looked like melted colby jack cheese running out. He tightened the cap and looked at me and said "You need a new engine. This one is completely ruined because someone ran it extremely hot. You have a TON of oil in the coolant system. Don't even bother taking the head off because after 20 years of doing this, it's just not worth the time."

Well crap.

I'm guessing between a $4-6K job.

Anyone got a 3.0 for sale?

FormerE30Owner

Let's not panic now. If there is a TON of oil in the coolant, then there is a TON of oil missing somewhere. Is transmission oil at the proper level - the engine oil? And what does 'running it extremely hot have to do with a ton of oil in the coolant system - blown head gasket, perhaps?
It doesn't take that much oil to emulsify coolant (ethylene glycol).

What did the oil look like in the valve cover? As good as the oil on the dipstick? Not sure what you meant by 'it looked like melted colby jack cheese running out'. Do you mean out of the expansion tank or out of the vavle cover cap?

You might have caught this before really doing major damage, contrary to your mechanic's opnion.

Salut, Bob P.

A B Able Truck

3.0 (N52) - doesn't that have an oil to water heat exchanger?

The oil-to-water heat exchanger is connected both to the oil circuit as well as to the water circuit of the engine. This arrangement ensures that the coolant quickly heats up the engine oil when the engine is cold and the coolant cools the engine oil when the engine is hot. Shortening the warm-up phase contributes to reducing the overall fuel consumption. The engine oil is cooled in order to extend its service life.

Spence73

The expansion tank oozed the Colby jack - super thick white paste if you will... white with streaks of brown. The Colby jack reference was from my old restaurant days :-)

The engine mysteriously lost a quart of oil in about a weeks time so I replaced it, three days later it wanted another quart. Now, it's asking for another one! So, there is about 2-3 quarts of oil in the coolant system.

The oil in the valve cover looked fine (other than being a little sludgy).

The expansion tank has developed a crack in the bottom slowly dripping out the white mess (added pressure perhaps?)

Dip stick? What dip stick? I'm not 100% but isn't this missing on the 07 (all sensor based)? If it's the tranny you're referring to then I'll look for it tomorrow.

The oil-to-water heat exchanger sits on top of the head right? On the front?

Anyway, I appreciate the efforts!