I have a 2008 E320 Bluetec. Purchased 4 years ago with 93,000 miles. The car now has 210,000 miles and running perfectly. There has been no repairs on the engine to date. It has the oil cooler that is prone to leaking and the mechanic that did the pre-purchase inspection found a small leak there. The dealer opted a $1,000 price reduction rather than make the repair. It has still not been repaired. It has never leaked enough to add oil between oil changes. In fact, it is now leaking less -- it does not leak enough to puddle in the belly pan over the 10,000 mile oil change interval.


The dealer had replaced the bottom ball joints front driver side before putting it on the used car lot. I had the two bottom ball joints on the passenger side replaced about two months ago.


Excellent car. Very happy with it. Fuel mileage over the last 50,000 miles averaged to 34.5 MPG. I paid $17,000 for the car in 2013.

I would still recommend doing the oil cooler job regardless. It really isn't that bad if you have all the right tools and take your time. If you have decent mechanical skills, everything in hand, and a copy of the WIS instructions you can do this over a long weekend. It will cost you under $1000, including buying the special tools, and give you serious peace of mind.

Reasons:
- the orange oil cooler seals will continue to degrade. Others on here have experienced sudden major oil leakage. Fortunately the deck below the cooler is set up so that the oil will drain down and not go into the coolant.
-This gives you a chance to clean the intake tract and replace the swirl flapper motor. This too will trigger a limp mode when the swirl flapper motor finally fails.
- You also get new crankcase breather pipe and puck. As the diaphragm in the puck starts aging, it begins to pass more blowby oil. This leaking blowby oil also drips down out of the turbo (from the joint between the air intake and the turbo), onto the swirl flapper motor.
- While you are there also replace the cam position sensor (since it will be uncovered while doing the rest of the work), this can stop you dead in your tracks if it fails. Ours started failing and threw a code, we were able to get it changed out before it fails.

It's coming up on a year since I fixed my oil cooler, the car has been running great and has not leaked a drop since.

If I purchased another pre 2011 OM642 I would be doing the oil cooler job on principle as soon as I got the car. Unless I had proof that it had been done of course.

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The OM 642/722.9 powered family
Still going strong
2014 ML350 Bluetec (wife's DD)
2013 E350 Bluetec (my DD)

both my kids cars went to junkyard in 2023
2008 ML320 CDI (Older son’s DD) fatal transmission failure, water soaked/fried rear SAM, numerous other issues, just too far gone to save (165k miles)
2008 E320 Bluetec (Younger son's DD) injector failed open and diluted oil with diesel, spun main bearings (240k miles)

1998 E300DT sold to TimFreeh
1987 300TD sold to vstech

Thanks for the update!

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[SIGPIC] Diesel loving autocrossing grandpa Architect. 08 Dodge 3/4 ton with Cummins & six speed; I have had about 35 benzes. I have a 39 Studebaker Coupe Express pickup in which I have had installed a 617 turbo and a five speed manual.[SIGPIC]

..I also have a 427 Cobra replica with an aluminum chassis.

Just curious, what happened for 2011+ did they update the design eliminating this as a failure point?

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1998 E300 turbodiesel

America's Rights and Freedoms Are Not The Enemy!

I think they changed the material of construction of the o-rings to something a little more durable.

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Jim

There are still reports of the new seals failing.

https://mbworld.org/forums/gl-class-x166/684688-engine-oil-cooler-leak.html