OM642 oil cooler

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R1ley

Member
Joined
Oct 30, 2020
Messages
35
Location
Carlisle
Car
Mercedes C320 CDI W204 2008
Hello, I decided to write this as yesterday I tackled the dreaded oil cooler on my C320 cdi. To start off, I will say that it is an absolute pig of a job. Especially if, like me, you get it apart finally and see signs of someone else having tried to tackle it beforehand. I had a snapped exhaust bolt and several pieces of broken plastic and small screws lying around the old cooler in the 'V'. It took me from 9 in the morning till around 7.15 p.m. to get the job done and when she coughed back into life it was a big relief. I didn't get many photos as my phone died on me (its a fairly old model) and I was covered in oil and antifreeze so everything was slipping out of my hands. I will run through a bit more later and try to upload the images I have taken too.
 
O.K. Here goes. Firstly remove the easy bit, bat wing comes off to access the general area you want. I then disconnected the top radiator hose from the thermostat housing. Next take off the aluminium turbo pipe by removing the screw and clamp at the bottom end (front of engine), and the bolt that holds the plastic unit it attaches to so you get some free play. Then unbolt and pull free the black plastic box like thing on the top of the black air intake pipe that goes to the intake manifold. Next, on the underside of this pipe, remove the 3 bolts that hold the EGR pipe in place. After this remove the 4 bolts from the black plastic intake pipe at the front of the engine where it bolts to the intake manifold. There is also a bracket at the other end of it holding the throttle body to the engine, unbolt that and disconnect the air pipe down there too. Once your sure all bolts are out and it is free, remove from the engine bay.
 
Now comes the fuel pipes and filter, I found it easier to remove the air boxes and take the fuel lines and rails completely off so i could get all the leak off pipes off and glow plug wiring too. In my opinion it made for easier access. To do this required me to also unbolt and loosen the wiring harness from the engine in the centre. It's held with a single bolt in front of the turbo and clipped to a bracket on the N/S of the engine. The fuel filter is held in place with some very obvious bolts and easy to remove after taking off the connected pipes too. The the turbo, 3 bolts hold the large elbow pipe to the back of the turbo along with a clamp that joins it to the main pipe. Then the EGR pipe is accessible at the rear which is a roughly 90 degree bent pipe, it has two flanges both held with 2 bolts. Once that is off, the exhaust manifolds can be disconnected from the turbo unit by removing the 6 bolts (3 each side). Now there are 2 bolts holding the turbo to its mounting stalk and a further 2 in a bracket further to the rear. Once they are out, the turbo should come away (with a little persuasion as its a tight fit). Then the swirl flap motor can be removed. This is held with 2 bolts and also has 2 clips connecting it to the flap control rods. Be careful here as the plastic rods can be brittle, luckily I only broke the clips but I had already bought replacement ones for just that reason. Now that's away, remove the turbo mounting stalk, 4 bolts and its out. Ok, so now on to the intake manifolds. Remove all bolts from both sides and take them out as one complete unit as they are joined by an alloy connector. Again, I bought a new one beforehand as they can apparently leak once disturbed. Removing the manifolds also removed the EGR pipework that was down there too so now you should see the oil cooler in all its obnoxious glory. Remove all the bolts holding it and be prepared for a lot of mess once its free.
 
I did clean the engine a bit more after the photos were taken too. And then its reverse procedure to get it all put back together again. Sorry if its not the clearest description or the best photos but I have tried my best to explain what I can. Please feel free if anyone has a question and I will try to answer the best I can.
 
Question
What on earth happened to the left side exhaust flange bolt ?
In any case both flanges & fasters look like they are "suffering" with some gas leakage on the right bank (as you look at it!) was that a pre-existing condition?)
I can see crap sitting in the pedestal port, did you not plug it up? Scary.
Orange seals observed so an early CD14 engine, latest & greatest are purple in colour .
Additional question.
How many miles on the engine /car at the point of opening it up, and what are your trip cycles on a daily basis --Curious!
Tuercas Viejas
 
Last edited:
Question
What on earth happened to the left side exhaust flange bolt ?
In any case both flanges & fasters look like they are "suffering" with some gas leakage on the right bank (as you look at it!) was that a pre-existing condition?)
I can see crap sitting in the pedestal port, did you not plug it up? Scary.
Orange seals observed so an early CD14 engine, latest & greatest are purple in colour .
Additional question.
How many miles on the engine /car at the point of opening it up, and what are your trip cycles on a daily basis --Curious!
Tuercas Viejas
Hello, yes the gas leakage was pre existing. The flange bolt you see was in the middle of being drilled out because it was snapped in there. Not by me, I found it like that. I did indeed cap the ports during cleaning but unfortunately, during using my airline, the thing blew off and some crap got there. I did get it fully cleaned before reassembly though.
 
Question
What on earth happened to the left side exhaust flange bolt ?
In any case both flanges & fasters look like they are "suffering" with some gas leakage on the right bank (as you look at it!) was that a pre-existing condition?)
I can see crap sitting in the pedestal port, did you not plug it up? Scary.
Orange seals observed so an early CD14 engine, latest & greatest are purple in colour .
Additional question.
How many miles on the engine /car at the point of opening it up, and what are your trip cycles on a daily basis --Curious!
Tuercas Viejas
I have indeed fitted the newer purple ones to the cooler and my car has 73800 on the clock. Mainly used by me on motorway and A roads. No idea how previous owner drive though.
 
Well I guessed it was a faily low mileage from the deposits in the manifolding.
Being a car in the US by comparison the mileages are around 12,000 /year with 15,000 being of higher mileage count cars, again more or less the same in Jeep Grand Cherokees.
Sprinters used to be the same but today a 2007 to 2009 CD14 pre-bluetec is rare bird to see in the shop The majority have long gone to the crusher or out to grass .
Most have about 250,000 on them if still runners, and the manifolding is often around 50% coked up.

Its the nature of the deposits which always interests me, (as in your specimen) since I believe bio blend distilled pump fuel is about 7% max in the UK whereas here, it can be as a low as 5% (B5) or as much as B20 dependimg upon which state the vehicle is used in.

A tip for stubborn manifold collector & turbo bolts !
We us a Dremel tool with flexi extension and mini grinding disc accessory kit to cut the head off without damaging the work piece area.
Then either remove the tail by convenational means, using a broaching tool bit & drill to centre punch the tail or use a mini EDM machine. thereby saving the threads.
In any case my shop rules are to go around and clean out all threaded vital holes , 8x1,25, 6x1 & 7x1mm. & then install new MB bolts .
Saludos
Tuercas Viejas
 
Well I guessed it was a faily low mileage from the deposits in the manifolding.
Being a car in the US by comparison the mileages are around 12,000 /year with 15,000 being of higher mileage count cars, again more or less the same in Jeep Grand Cherokees.
Sprinters used to be the same but today a 2007 to 2009 CD14 pre-bluetec is rare bird to see in the shop The majority have long gone to the crusher or out to grass .
Most have about 250,000 on them if still runners, and the manifolding is often around 50% coked up.

Its the nature of the deposits which always interests me, (as in your specimen) since I believe bio blend distilled pump fuel is about 7% max in the UK whereas here, it can be as a low as 5% (B5) or as much as B20 dependimg upon which state the vehicle is used in.

A tip for stubborn manifold collector & turbo bolts !
We us a Dremel tool with flexi extension and mini grinding disc accessory kit to cut the head off without damaging the work piece area.
Then either remove the tail by convenational means, using a broaching tool bit & drill to centre punch the tail or use a mini EDM machine. thereby saving the threads.
In any case my shop rules are to go around and clean out all threaded vital holes , 8x1,25, 6x1 & 7x1mm. & then install new MB bolts .
Saludos
Tuercas Viejas
Very sensible shop rules, I did clean the threads on the exhaust flanges and fit new bolts when reassembled. I guess over in the states cars cover much more distance than over here in Britain. Mine is a 2008 model and still feels really good to drive, mostly due to the lower miles I think.
 
Very sensible shop rules, I did clean the threads on the exhaust flanges and fit new bolts when reassembled. I guess over in the states cars cover much more distance than over here in Britain. Mine is a 2008 model and still feels really good to drive, mostly due to the lower miles I think.
R1ley
Guys
I mentioned broaches to remove broken bolts especially when pulling out the turbocharger OM642 engines.
Usually a bolt or stud doesn't sheered flat, its either a cup & cone failure or a slanted sheer seperation . The old fashioned way of trying to centre punch the work piece and drill a straight hole is often difficult and it ends up doing the dance of the sugar plum fairy.
So studs and bolt removal is a chore.
Taking a page out of general machine shop practice is the broach kit adapted for ham fisted mechanics and DIYrs alike.
Being small for use in tight spaces the kit allows you with a hand drill to flatten the sheered face, then centre cut a dimple in the material before taking a centering drill broach to the job totally preforating the work piece , then following through with a standard carbide drill.
Done right & you won't get called "Baxter the Butcher" in an auto repair shop,
These things come in 6, 8, & 10 mm sizes as well as US/UK fractional .
See if you can find them on your side ,'
Cheers
Tuercas Viejas

 
R1ley
Guys
I mentioned broaches to remove broken bolts especially when pulling out the turbocharger OM642 engines.
Usually a bolt or stud doesn't sheered flat, its either a cup & cone failure or a slanted sheer seperation . The old fashioned way of trying to centre punch the work piece and drill a straight hole is often difficult and it ends up doing the dance of the sugar plum fairy.
Very sensible 👍
And not very often I here people using specialist metallurgical terms like 'cup and cone fracture' 👍👍

I don't think I've personally come across any cup and cone, they have all seemed to be slanted sheer fracture. In the past, I have also used the flexi extension on the end of a Dremel, and I use the smallest circular cutting disc (about 15mm diameter at a guess and 1 or 2mm width) and put a tiny cross over the top of the stud. It's been enough that a nice sharp carbide bit can then cut into the centre of the cross, and I haven't needed to flatten of the fracture surface.
 
Very sensible 👍
And not very often I here people using specialist metallurgical terms like 'cup and cone fracture' 👍👍

I don't think I've personally come across any cup and cone, they have all seemed to be slanted sheer fracture. In the past, I have also used the flexi extension on the end of a Dremel, and I use the smallest circular cutting disc (about 15mm diameter at a guess and 1 or 2mm width) and put a tiny cross over the top of the stud. It's been enough that a nice sharp carbide bit can then cut into the centre of the cross, and I haven't needed to flatten of the fracture surface.
Well its all down to Young's modulus of elasticity.
Over tighhten the bolt or stud and it breaks in a cup 'n cone facture.
Unless its a glowplug!
OMG stuck glow plugs.
Last year I think it was a shop record !
I removed no fewer 31 glowplugs in one callender month from MB engines.
Happy days .prostrate over an engine :rolleyes: .
Tuercas Viejas
 

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