Rear oil leak
 

We have a 2010 e60 with the N52k.

I just replaced the oil cooler gasket and oil filter housing gasket. The vehicle only has 48,000 miles in her.

I caught the oil leak early. I saw a few drops of oil on the electronic water pump. I couldn't see any oil drippings coming from the valve cover gasket, so I assumed it was the oil cooler. I was able to identify it was leaking just a little using white paper towels. I didn't see any oil on the pulleys, serpentine belt, hoses or front of the engine near the vanos and cam sensors, but here comes the odd part.

When I got under the car, I noticed the extra large protection shield covering the transmission was soaked with engine oil. I took it off and tried to see where it was coming from. There were no obvious areas.

The car only has 48,000 miles on it. Is it possible the oil leak is coming from the rear main seal and I can't see it? Would the rear main seal be leaking at 48,000 miles?

This can be really tricky. I just finished pulling my N54 apart - i had oil leaking from the back of the valve cover gasket, down in the space between the block and the transmission bellhousing, coming out the bottom looking like a rear main seal leak. I pulled everything apart suspecting a rear main seal leak - and it was fine. (I changed it anyway). My suggestion would be to start at the top and work down - inspecting the back of the valve cover gasket / head gasket, will be tough because of the space issues, but try to get in a with a telescoping mirror and see as much as you can. Have you done the valve cover gasket yet?

I have not changed the valve cover gasket yet.

I've check the valve cover gasket a few times and it looks ok, but I never checked it back at the firewall. I'll try to get a rag back there or buy a better mirror. Its hard to see anything back there.

Even though I have just changed the oil filter housing gasket and oil cooler gasket a few days ago, what I'm finding out is the new oil cooler gasket is not that good and its currently leaking.

Bentley says the torque should be 16 ft lbs, but its still leaking. I have read other forums that says you need to torque the oil cooler between 20 ft lbs to 22 ft lbs to seal it properly or it will leak.

Won't 22 ft lbs strip that oil cooler bolt?

Does everyone just use Permatex Ultra Black with a new oil cooler gasket so the job is successful?

2009 528xi. Replaced the oil filter housing gaskets a year ago and torqued to spec. Never used any RTV / Permatex etc. You should not have to. My notes say 22 Nm, which is approximately 16 ft lbs.

You have a leaking valve cover gasket in the back corner, or a leaking oil pan. Probably both.

Good work. You were right. I do have a leaking oil pan gasket.

It took a lot of investigation because it wasn't easily visible. I've included a picture of the gasket leak (attached).


https://cimg1.ibsrv.net/gimg/5series...194834496d.jpg

I didn't know how the previous owner took car of the car before I bought it. In order to get the engine clean, I changed the oil frequently so that the engine would burn clean. Over the course of 6,000 miles, I changed the oil 3 times (every 2,000 miles) to get it clean.

Is it possible that frequent oil changes are making the oil pan gasket leak and the oil cooler gasket leak?

No. Frequent oil changes will not lead to gasket failure. If anything, additives in new oil will prolong gasket life.

Beware of NOS (new old stock) gaskets. Remember, German-made rubber parts only have a short finite lifespan once manufactured, possibly as little as 7-10 yrs, regardless of use.

I purchased a German-made set of valve cover gaskets for my N62 V8 and they were soft and pliable before installation. Both started leaking and within a few months I decided to replace them again. I was surprised when I pulled them out, they already became hard and brittle as if they had been in the engine for many years.

The only theory I can come up with is that this VCG was new and sitting on the shelf for quite awhile. The second set of gaskets I installed has been leak free.