TxRzrBk

I just completed oil cooler seal replacement on my 2011 GL350 and it seems it's still leaking. It's only been driven about 30 miles since replacement. I'm confident everything was clean and the bolts were properly torqued. I'm wondering if it's common and/or possible for the cooler to leak following seal replacement and subsequently seal?

I'm really defeated, this was a nightmare job that spanned almost a week...I'm shocked it turned out this way and probably going to get rid of the car if the situation doesn't improve

DennisG01

Well, first, kudos to you for taking that on yourself. I like doing as much of my own maintenance that I can but this was one of those things I was glad to pay someone for. However, I was lucky enough to be able to hire a local indy's mechanic "off the books" (it was actually the indy's idea as they were swamped).

But, back to your question... no, it's not normal for something to be fixed and then immediately leak again. I think there's only two explanations here and you probably already know what they are. One, the job wasn't done properly. Two, there is different leak that you are misdiagnosing as an oil cooler leak.

Side thought... since I didn't do the job myself, this is more of just a general wonderment-type question... would it be possible to re-locate the oil cooler to the front of the engine, either behind or in front of the radiator (like many, many other cars)? I imagine it would involve installing a block-off plate in lieu of the cooler and then getting the oil supply for another location and return the oil to another location. The block-off plate would need to be more substantial and permanent than the cooler to avoid the same leakage problem down the road.

Don't give up the ghose just yet - fixed properly, it should be a long-term fix.

TxRzrBk

I really can't think of anything that wasn't done correctly. The oil cooler is very hard to access but removing the cooler itself and changing the seals is dead simple. the oil cooler seals hold oil on one side and coolant on the other side, its odd that no coolant leaks.
I suppose its also possible that the oil I am seeing is residual oil from the leak. I thought I did a good job of degreasing but there is a passage near the turbo pedestal that could hold some oil.

The only other possible sources of a leak that I can think of are the turbo or turbo pedestal but maybe I am overlooking something.
As far as relocating the cooler, not easily but I suppose anything is possible.

91stealthes

Are you sure it is the oil cooler still leaking?

Dealer originally thought it was my oil cooler leaking but turned out to be turbo seals.

DennisG01

I'm familiar enough with the procedure to understand what you're saying about the actual install of the cooler is straight forward. Only thing I can think of is maybe a seal that got slightly dislodged during install?

If you don't already have one, now would be a good time to buy an inspection camera - you can get the actual cable/camera pretty cheap online - they hook into a phone or computer. Then you could maybe see exactly where the oil is coming from.

But, first thing I'd do is to spray a whole bunch of degreaser down there and let it set for an hour - then gently flush with water. That way if there is any residual, that should take care of it. Then monitor closely, now that everything is clean, for a drip trail.

TxRzrBk

By turbo seal you mean the orange silicone inlet seal? I know mine needs replacing but I also just installed a catch can. Now that I think about it there is probably enough oil in the charge air lines to leak some oil, I'll look into this.

I'm 99% sure the oil cooler was leaking prior to the repair. As of now I have not investigated enough to be certain about the source of the leak post repair, an inspection camera is a great idea.

As far as degreasing, I used a half gallon of power purple in a pump sprayer followed by a garden hose, this was done after installing the cooler but prior to intake manifolds as well as after final assembly was completed

klxman95

Mercedes dealer replaced my oil cooler seals 3x under warranty before I diagnosed the turbo inlet seal as the real problem. I was really surprised the shop foreman of a large dealer did not replace the turbo inlet seal after the second time - it showed wear and was 7 years old. New seal was much harder and fit better, no leaks.

Only reason I diagnosed it myself was because the repair warranty ran out, so the fourth oil cooler seals would have been on my dime.

My suggestion - replace the turbo inlet seal, make sure it is fully seated on the turbo inlet and clamped, clean out the valley really well of residual oil, clean out weep holes/bellhousing underneath of oil. Watch carefully as you drive to see what happens. I had to wait about 400 miles for all the residual valley oil to drain out (even though I flushed valley with detergent). 5000 miles later and no leaks.

TxRzrBk

Thanks for the guidance, I feel confident the repair was done correctly but I was unsure how much residual oil the engine might hold. While I plan on replacing the inlet seal the oil catch can should dramatically reduce if not eliminate the oil going through the intake. This was something I decided to do after seeing all of the "tar" in my intake manifolds. Long-term I plan to eliminate the egr because I have no doubt the intake build up will continue to be a problem and removing/cleaning is far from a trivial task.
In hindsight replacing the oil cooler seals wouldn't have been that bad if it were not for 2 issues. 1) the jeezless copper E12 bolts behind the turbo. I soaked them and was careful and patient but still ended up stripping one of them. I tried everything under the sun over a period of 4 days and nothing worked. I ended up making my own extractor socket and finally broke it loose. 2) the egr actuator - while it's not strictly required to remove it gives more access and that was required to deal with the stripped bolt. I ended up finding a YouTube video with a very simple approach involving a chisel and hammer and that popped it right out.

91stealthes

Yes, it was the orange inlet. The engine, turbo, and seal only had about ~8,000 miles on them.

TxRzrBk

Update - notice a strong smell of diesel when the wife pulled in last night. Popped the hood and one of the injector oil lines was leaking. It seems what I thought was an oil leak was a diesel leak, the diesel was washing down the residual oil from the original cooler leak.
Leak fixed and another round of degreasing...fingers crossed.
So far the catch can had only about a tablespoon of condensation