2008 ML320 CDI - Oil Cooler Seals Replacement
Decided to replace my oil cooler seals on the OM642. I had a 'mystery leak' that was appearing on the driveway from the drivers side rear of the engine block. Eventually traced to the center of the valley of the V6 and the obvious culprit (after much probing with the boroscope) was that the oil cooler seals were failing.
Car has about 175K on the clock.
I also cleaned the intake manifolds, EGR plumbing, swirl motor flaps, and intake ports of the heads of the EGR+oil goo that was coating everything.
I took some photos and even have a time lapse video that I'm working on. The photos are already up so here's a link:
https://plus.google.com/photos/11000...23881113808401
If linking to third-party photo sites are not allowed, I can put a few up here if needed.
Hope these help someone and I'm happy to answer any questions if anyone is thinking of doing this job themselves. It took me about 9-10hrs with some help with the cleaning process. I also tore down the turbine housing to inspect the VNT/turbine (which took extra time) because I suspected some damage (which there was).
The swirl motor linkage was by far the most fragile part of the experience. I heard the horror stories so I was ultra careful disconnecting things. Spent about $50 in parts from Mercedes (gaskets) to the job.
Take care,
I figure I have another year or two till I have to do the same. Not looking forward to it. Not out of fear, just getting lazier every day.
The cleaning was the worst part. Clearly vacuumed up the most time. Very rewarding driving the car to the shop, doing the job, then driving it home at night.
I'm going to have to keep my eyes open for a turbine wheel. That one has passed some material (guessing either chunks of carbonized goo from the EGR+oil or something from the drivers exhaust manifold...which had the inner pipe weld crack). I re-welded it before re-installation :-)
Last edited by Brandon314159; Feb 27, 2013 at 07:59 PM.
The cleaning was the worst part. Clearly vacuumed up the most time. Very rewarding driving the car to the shop, doing the job, then driving it home at night.
I'm going to have to keep my eyes open for a turbine wheel. That one has passed some material (guessing either chunks of carbonized goo from the EGR+oil or something from the drivers exhaust manifold...which had the inner pipe weld crack). I re-welded it before re-installation :-)
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Brandon, can you chime on that time lapsed video.
Thank you,
Doug
The Best of Mercedes & AMG
Thanks for great write up!
will be great if you can upload video, or some details, do u have any tricky moments with some parts?
Last edited by Sammydavis; Nov 21, 2013 at 06:27 PM.
Will update when i am done.
plus recommended fuel filter 68$. so in total 200-300$ on parts depend if u decide to change air and fuel filters.
there is 2pg with all parts#, but u can bring all gaskets to MB parts and they will find all of them. for you.

Really hoping that some sensor connector got saturated with oil and just got some high resistance short.
At any rate, I have my seals and plan to attack this on saturday am.
Any final words of wisdom would be appreciated. Hearing the turbo can be a pain in the ****...not sure why just yet...
Wish me luck.
Mike

1. Mercedes changed the seal material to viton; I ordered these about 3 months ago and they were orange. Friday, I stopped at the dealer and they are now under a new part number and are purple viton material.
2. Get a subscription to Alldata diy. Kinda difficult to get all the pieces to the big picture as you have to kinda jump around. Print the procedures and pictures along with the torque specs. Might even be good to pencil the torque values on your printed page that shows the bolt locations.
3. Get some swivel head ratchets. Brandon suggested these. These are virtually mandatory. I got a 3 piece set from H-freight along with a torx set. Will need the sockets and the bit type. These swivel ratchets will be my new goto ratchets unless I need a bunch of torque.
In a nutshell. here are the steps.
1. Remove the shroud and turbo shroud.
2. Remove both Air Filter enclosures.
3. Remove the left aft and center heat shield and insulation.
4. Remove the turbo and oil supply standoff
5. Remove the left fuel rail and the crossover fuel line that goes from right to left. Also had to undo the lines on 2 injectors to get the rail off.
6. Remove the EGR; Valve on the back left top of the manifold with a couple of coolant lines attache to it. Cheap set of hose clamp pliers worked well for theses as they are in a tight spot.
7. Remove the front side air box. Plastic housing at front of motor. First pull the air baffle box. Then pull the glow plug relay and bracket. disconnect the 2 screws that secure the assembly to the right forward engine bracket. You will also remove the dipstick bracket here as well.
8. Remove the turbo. These bolts (The ones that attach to exhaust manifolds) are tight as hell with not much room to work. Used the swilvel ratchets where I could, used 3/8 straight ratchet with a 3/4 deep well to give a better grip and a little added extension. Critical to make sure your torx is seated to the shoulder and keep the ratchet square when turning and you should be able to get them off without breaking.
9.Remove the turbo oil supply block.
10. Remove the charge air manifold. Undo 20 or so bolts (Look for the 2 left aft that are recessed; you'll see them. I just left the swirl motor attached and slid the assembly aft and then lifted the whole thing out. Then remove the swirl motor and unbut the 2 halves of the manifold.
Now the fun part. Parts Cleaner; tooth brush; baby bottle brushes; paper towels etc. soak the manifold down then power wash the hell out of it. remove the egr cooler assembly. It will be loaded with crud as well. Soak, Brush, power wash and flush.
Plastic front air assembly also will be loaded with crud as well; you know what to do. Soak scrub and powerwash.
When you see the intake holes on the cylinder head, you will wonder why you drive a mercedes diesel. Clean it anyway you can. I scraped what I could with a small jewelrs screwdriver and shop vac'd the crud out as I went.
I have the oil cooler resealed; the charge air manifold and front side back together but will need to get a new swirl motor this week as mine was blowing F104 and left a puddle of oil ont the table where it overnighted.
I plan to get it back together later this week after I get the rest of the parts.


