This is an excellent video that tells you where are the weep holes. I will inspect the two on the side and run a wire to see if there is oil around the oil cooler. If there is oil than that proofs oil cooler needs to be replaced along with the seals. I replaced the seals 6 months ago, I think it’s either the rear main seal or the oil cooler again.

https://youtu.be/ZgjxbNbH-pA

Oil filter housing can leak on these engines

Correct, I replaced the oil filter housing seals https://rover.ebay.com/rover/0/0/0?mpre=https%3A%2F%2Fwww.ebay.com%2Fulk%2Fitm%2F192362694307

Interesting about the swirl flap motor. Just reassembling this today and for the life of me I couldn't attach the clip into the arm on the underside. Ended up taking the LH manifold out and attaching the clip and motor and then bolting it to the manifold to stop it flapping about. With a bit of faffing and an hour later I managed to put it all back into position with the connecting aluminium joining bush square in each part of the manifolds.

Real pain in the A to do. Hopefully never again !

Looked up the positions of the flaps as I was concerned how this all worked (never had to work with swirl flaps before)

From what I've read and seen videos of - the left hand manifold (as you look at it) the arm faces towards the front of the engine and the right hand manifold the arm points towards the back (so opposite directions).

Hopefully this is correct as I didn't see it in your instructions (unless I've missed a bit)

Great write up by the way. Really helpful with photos and corresponding torque settings. Saves other people (such as myself) hunting them down which can take ages.

Much appreciated

Hi there guys, sorry for resurrecting this thread but i have a issue with my OM642 i did the oil cooler installed everything forgot to tighten the turbo oil spilled out again took everything off cleaned it then reinstalled everything then tried to start again and the car didn't wanted to start it just cranks over and over and over prior to the oil leak (first reassembly it started on the 4th crank) now it will not start is it possible that since i broke off the brake booster hose (small tip off it car will not start?) I ordered one but it takes a week until it arrives or i'm missing something thank you.

Hello its been 9+ years since I've posted this guide and I thought i'd give an update on these Mercedes OM642 and its problematic oil cooler seal.

The vehicle that I wrote about in this guide the E320 Bluetec is no longer with me, however I do have a couple of GL320's CDI (with OM642) and another E320 Bluetec (also OM642) that are running around, however one of my GL320 has developed an oil leak just like my old E320 Bluetec, except it leak copiously at the front, initially I thought it was the oil filter housing but turns out it wasn't, it was the oil cooler, and yes there is front weep hole.

The GL that I'm working on showed that the oil cooler were done in 2011 according to Carfax at Mercedes dealer this was later verified when I called that dealer and was confirmed it as done there at that time.

So off I when digging into the past to excavate the infamous oil cooler from OM642, surprisingly its easier on the GL320's then the E320 there's more space in the back in the turbo/exhaust/egr once you remove the engine firewall/cowl/isolator's,

https://www.peachparts.com/shopforum...1&d=1724006928


And a 6 hours later oil cooler is out, it gets easier the 2nd time around and not freezing cold either

https://www.peachparts.com/shopforum...1&d=1724008673

And to confirm my suspicion the updated seal are in and the seem last only 10 years to so with unknown service history.

https://www.peachparts.com/shopforum...1&d=1724007430

Another purple seals are on and its on to the roads again, perhaps for another 10 years...I hope longer

https://www.peachparts.com/shopforum...1&d=1724007327

Findings, Remember how the oil cooler has one passage for oil and another passage for coolant upon removal of the oil cooler with the old purple seals intact, the oil side of the seal was so swollen up to a point it compromised the seal and sprung a leak on the oil side at the front of the engine/front oil cooler, while the coolant side of the seal has remained collapse/compressed and was sitting flush with the surface of the oil cooler.

https://www.peachparts.com/shopforum...1&d=1724007924

Conclusion, These purple seals are good for about 10-15 years or 100k miles or so with unknown service history. It seems like its a design flaw from Mercedes with its oil cooler placement (extreme temp and vibration) and seal design, I think the updated Viton (purple) prolongs the problem at later time (or till warranty expires really) as it will resurface again in a decade or so. Expect this to be a every 10 year maintenance routine.

Thanks for update. It seems like they could have installed external oil cooler to keep from having to go to all that trouble.

We have a 2012 GL450 v8 that is easy to maintain. It is one of the best trucks I've ever owned.

Yes I wished they've would have piggy back the oil cooler on to the oil filter like most of their gas powered vehicle, however looking at R class, Sprinter, and E class chassis, there isn't much space up front to place a similar sized cooler that this engine requires on to the oil filter housing, and this engine is build in the era of modular architecture so this engine has to be able to fit into almost every Mercedes line up with as few as possible modification this is part of the result why the oil cooler sits in the V of OM642.