turboawd

how long have you had the car? know the history?

A B Able Truck

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http://prodcds.bmwuniversity.com/lib...2%20Engine.pdf

Redtwin

I don't buy the "You need a whole new engine". It could just be a bad head gasket (or heat exchanger if it has one). Remove head, check for warping, skim if necessary and fit a new headgasket. If the engine was running fine before the fault occurred (no knocking or rough running) then it should be OK.

Of course if your mechanic is telling you that the above work will cost as much as or more than just fitting a used engine, then that's a different story.

A B Able Truck

If it does have a heat exchanger - you can take it off and have it pressure checked before picking on the head.

FormerE30Owner

I think we know what oil we are talking about! Its engine oil.

This might not end up a dire as you fear, since it appears that the oil is leaking into the coolant, but the coolant has still done its job, since you claim that the engine has not overheated.
Find the source of the leak, repair, flush out the cooling system and replace the coolant and see.

Salut, Bob P.

Spence73

Now the tech is telling me that there is a known issue with the engine oil cooler failing and mixing with the coolant... so, that means you guys are way ahead of this dude and you haven't even seen the car. Nice.

However... I am finding multiple coolers in the engine bay. I've also located some on eBay but one pic says its the engine oil cooler and the same pic down the list claims it's the transmission cooler?!

I've also came across a couple threads talking about the oil cooler gasket failing and causing this.

Which cooler do I need?

BMW 17217559960 Genuine Factory Original Oil Cooler | eBay

or

BMW 11427525333 Engine Oil Cooler Oil Cooler | eBay

A B Able Truck

Should be the second one - but I would think it's a gasket problem with the cooler.
BMW 11427525333 Engine Oil Cooler Oil Cooler | eBay

Spence73

I learned that the guys changed the oil filter housing gasket prior to selling it to me and I also removed the oil-coolant cooler and the gasket 'appears' to be OK, it's still flexible and not brittle but I'm replacing it anyway. I'm also replacing the oil filter housing again just in case they screwed it up.

I'm assuming that since there is oil in the coolant and no coolant in the engine it actually could be a gasket as oil pressure is higher than coolant pressure correct?

The tranny fluid is excellent so that cooler is working properly.

The oil contamination is substantial however, does anyone have the proper flush technique and chemicals used on the engine? I was told Simple Green was very good at doing this job but I want to make sure before I potentially damaged the aluminum.

I didn't see an electrical water pump (as on the X5) so i can assume it has a mechanical pump?

After the flushing is completed I'll replace the thermostat as well.

I've had a few 3 Series but this is my first 5 so I do apologize for the simple questions but the simple things tend to burn you faster than the major ones. :-)

Spence73

Just an update:

I removed the oil cooler and pressure tested it with 40 PSI.

I submerged the cooler in a tub of water (after cleaning it) and covered one side of the coolant hole with my finger and pressurized it... no leaks/bubbles coming out of the oil holes.

I repeated the process for the oil hole... I got 1 good size bubble every 1-2 seconds coming out of the coolant holes. Bingo. Bad oil cooler.

This explains why I have oil in the coolant but no coolant in the oil.

$130 for a new cooler and I'm back on the road.

Thanks for all the help everyone!

pcy

excellent, you saved yourself a ton of money.

I'd recommend you to change the oil as well as coolant flush, just to make sure remnant fluids are not lingering in the system.