A journey into the the infamous Om642 oil cooler leak! - Page 3 - PeachParts Mercedes-Benz Forum

jay_bob · #1 01-10-2015, 09:37 AM

Thanks for posting this again. I vote this goes into the wiki when it's done.

Before things get too far out of your memory, can you post a bill of material of everything you had to order for this job?

funola · #2 01-10-2015, 11:16 AM

What a nightmare to fix an oil leak! I'll make sure to never buy a car with the Om642. Any reason why Mercedes put the oil cooler (a FPHE) at the bottom of the Vee and not in a more accessible location?

leszek · #3 02-09-2015, 05:24 PM

Good point on the question of "why did they put the oil cooler in the vee"? Ford did the same thing with their 6.0 International diesel. They did not have a leak issue, they had a coolant side clog issue which would snowball and cause EGR cooler failure which then caused head gasket failure. No clue why they both don't place these somewhere external. Of course I guess you could say that about half the parts on the engine which would then require an engine compartment of a mid 70's Cadillac.

Actros617 · #4 01-10-2015, 04:05 PM

Quote:

Originally Posted by jay_bob

Thanks for posting this again. I vote this goes into the wiki when it's done.

Before things get too far out of your memory, can you post a bill of material of everything you had to order for this job?

Here's your parts list. I bought them at (genuinemercedesparts) they have all the seals you need, the dealer around my area wanted $280 for the seals vs that site at $150, parts are OEM Mercedes. Pelican parts has only a handful of those seals.

Quote:

Originally Posted by funola

What a nightmare to fix an oil leak! I'll make sure to never buy a car with the Om642. Any reason why Mercedes put the oil cooler (a FPHE) at the bottom of the Vee and not in a more accessible location?

The OM642 engine is a Modular Design, its a simple, easier and cost effective measure to manufacture 1 engine that can be plopped down into any (2007 to 2013+) mercedes chassis line up they have, however one downfall of modular engine is it has to be a compact design so that the engine will fit into any Mercedes w/o structural modification, that means every module that is needed for the engine is crammed and stacked on the engine, and the oil cooler been unfortunate is why its located in the middle of the engine.

Let this not discourage you to buy a Mercedes with a OM642 it may seem intimidating to repair but its pretty straight forward, ones that the oil leak is repaired its pretty much good to go for years to come, and besides for the past 2 years of ownership it prove its self quite reliable despite been technologically complex, just change your oil on time and services it on time.

engatwork · #5 01-10-2015, 06:16 PM

Quote:

Let this not discourage you to buy a Mercedes with a OM642

I agree.

Once it is sorted won't have to mess with it. I sure do appreciate this thread

. One of my best customers has a 09 E class bluetec and I am starting to see oil leakage on the back of the engine area so I suspect it is just a matter of time I have to deal with it. This thread will come in handy.

Thanks

ashedd · #6 01-13-2015, 05:28 PM

Is that the SAME parts list for the CDI? 2008 R320...

Thanks

drapersmeadow · #7 01-17-2015, 11:57 AM

Excellent posting ASTRO...I was a few days ahead of you on my 2009 ML320 w/ 99,800 miles. It was one of those jobs that must be very methodic and you covered it very well. It does take many hours to complete. POLARISRMK remark that it is a 5 hour slam dunk is smokin' somethin'! Good 20- 30 hours or more and half of it is cleaning and thinking it through as a one man job weekend warrior.

HELPER HINT: Took my turbo off the same way...but could not access the mounting bolts for the bracket on the reinstall...dropped one and luckily found it. Took a chance and removed the bracket (2 bolts you could not remove) installed mounting bracket first. No blind spot like with turbo in the way. Then installed turbo and the 2 bolts. Much easier. More than likely one of the "tricks" that regular MB techs know! Turbo drops in cleanly also.

Skid Row Joe · #8 01-13-2015, 07:15 PM

This thread should be added to the *Stickys* reference list of DIYs atop DD in this Forum @ some point.

pokeyarw · #9 01-24-2015, 10:00 AM

I just bought a 2007 E320 Bluetek. It's in mint condition (the proverbial schoolteacher car) and has just 70K on it.

I've been reading about the oil cooler gaskets and am wondering if they fail as a result of time or use. As with Actros617 I don't have a heated garage and would not like to do this job just now. As the car has only 70K, one might suspect I have some time to go before the failure, but if it happens after seven years, then I better get on it.

Also, it is unclear to me whether the failure is catastrophic, i.e., shuts down the vehicle either by COMAND or by being unable to keep enough oil in it to run. Descriptions seem to imply oil streams out pretty rapidly, but no one seems to have had to have the vehicle towed for the failure.

The book time to do the job is just under 10 hours. How accurate is that?

clacker · #10 02-19-2015, 11:27 PM

Nice write up! Love it.
Word of caution though about all that carbon in your engine-change your fuel supply or start running lots of fuel conditioners to bring it up to spec. I removed my egr valve at similar mileage (120k) and it is still whistle clean, just a black coating that wiped off with a rag no deposits anywhere. I run 47-48 cetane fuel and lots of conditioners, never push a cold engine and generally take it easy on it (no Italian tune ups) but I tow with it about once a month (5X10 double axle, or car on tow dolly-significant weight). Only highway driving. I would also change the oil more often, I am doing 6-7k intervals to help prevent the oil cooler seals from blowing out and changing air filters often to keep things breathing well. It seems clogged air filters mean more drag on the crankcase breathing system and internal pressure, there was good write up on it on another forum. Running the oil long means more blow by/fumes too, and mixing with the egr soot and carboning up.

biopete · #11 02-20-2015, 01:23 PM

Wow! Nice write up Actros617 and nice work. Thank you. How hard is it to change the glow plugs on that engine? it must not be very hard. I would have been tempted to pull them all and replace while everything was off and I was staring at their brittle little plugs.

Actros617 · #12 02-23-2015, 02:34 PM

Quote:

Originally Posted by biopete

Wow! Nice write up Actros617 and nice work. Thank you. How hard is it to change the glow plugs on that engine? it must not be very hard. I would have been tempted to pull them all and replace while everything was off and I was staring at their brittle little plugs.

Replacing the glow plugs are tricky because there's a chance of shearing off the glow plugs because its seized in the block, according to MB service manual it reccomend you to warm up the engine to operating temp and remove glow plug so it wont break and leave the glow plug tip in the head, if the it break off you have to extract it ie tap into the glow plug tip using an extractor, or remove the cylinder head to remove it.

Actros617 · #13 02-23-2015, 04:38 PM

Finale

So this picture is here to illustrate whats going to be installed.

Heres the intake manifold replace the O rings, highly important to prevent boost leak

Now heres is the EGR attach this end on to the Black pipe (theres a cut out in the middle of the black pipe you cant miss it)theres also a rubber gasket on the EGR pipe replace to preven boots leak, 3 bolts holding on it 15 nm

Triangle end goes into this black pipe

now that you have the EGR pipe attached (simulated EGR image) on to the replace the gasket as shown to prevent boost leak pipe, then take charged air pipe to intake manifold intercooler have to push in and make sure that the left intake manifold and the EGR pipe are seated properly and flushed, theres only 3 bolts holding on the intake manifold torque to 20nm

Heres the charged air line installed to the intake manifold

Next thermostat, replace the gasket on it and attach to the intake manifold torque to 20mn 3 or 4 bolts total dependent on certain model, mine had 4.

Next install the electronic controller for the throttle body it just sits right on top the the charged air hose to intake manifold, connect the connectors,

Then install the bracket for the electronic controller for the throttle body, its a clamp style bracket, 2 bolts and 2 nuts 5nm torque

Install the resonator pod, im not sure what is that thing dose but it looks like it just covering an extra hole. inspect the o ring on it, and then give it a good push, it should pop right in and 1 bolt to secure to the charge air to intake manifold 5 nm torque

Now install the turbo silencer, one end (silvery pipe) attaches to the outlet of the turbo theres a O ring that slides on the turbo outlet, MAKES SURE IT THERES, or you'll make no boost! The other end (see picture) is the silencer, this part attaches to the intercooler, and theres 1 bolt, a very long bolt 10 nm make sure you bolt it down or you'll run the risk of the pipe getting dislodged

Then attache all your hoses, Intercooler, Coolant, Air intake and the bat wing, air filter and fuel filter

Now fill up your car with BLUE Coolant purchased from the dealer, it only comes in concentrate, just get some distilled water from your local supermarket. It will take approximately 2 gallons of coolant.

NOTE some cars with OM642 ie ML and GL uses yellow coolant,

Now that the coolant is filled, its time to start up the car, now since I've removed the fuel rail and fuel filter, its wise to cycle the key 2-4 times so that the fuel filter is primed (you have a electric fuel pump) then try to start it up, now it will take 2-3 start/cranking cycle for the car to actually start up because its purging air and building pressure in the fuel rails and the lines, ones fuel pressure is sufficient the car will fire right up with little to no hiccups.

Now that you're finally finished and you've been rewarded with a garage that looks like after a surgery is completed, MESSY!

Final IMPORTANT notes
Check your coolant level, Oil level, Coolant temperature for the next 1 week, and check for leaks, leave all under panel off so you can detect a leak, if you have a lean then you may have to go back in there and find out what hasn't been tighten properly hopefully not the oil cooler .

engatwork · #14 02-23-2015, 05:17 PM

Good job.
Appreciate the follow up.

catalind · #15 03-24-2015, 02:14 PM

Astros, many thanks for your efforts to document step by step the oil cooler seals "challenge". Your instructions were very helpful.
Yes, I had a leak on a 2010 ML Bluetec with 89000 miles on it.
The cooler seal was previously changed 2 years ago at 58000 miles. As you guys reading this post know, the leaking source is very hard to spot. The oil was dripping at the bottom where the engine/ transmission are joining together and the main clue that the leak originates to oil coller seals was the wetness of the weeping hole (driver side of the engine).
I changed the cooler seals ( put the purple ones now, back in 2012 the dealer used orange ones).

One point that I noticed when I took out the cooler was that the bolts close to the turbo were almost "hand tight". Took me no effort to break them out. ( probably the seals collapsed and there was no more load on the bolts). To avoid a similar situation in the future, I used spring washers this time.

Everything good with the oil cooler, parts got back in place, beautifully cleaned with no incidents.
Started the car ( bunch of errors codes related with the exhaust back pressure). I have an exhaust leak between turbo and the exhaust flange ( I can feel it and smell it of course). I will take care of that.

The very, very sad part is that I still have oil leak under the car.
The oill clearly is not coming from the weeping hole on the side of the engine. See the attached file.

It is hard to detemine if is main seal, it could be but I am puzzled why there is no oil dripping right at the center or why I cannot find a bunch of oil insde the bellhouse.

One thing is clear, is not the oil cooler because the weep hole is DRY.

Any idea? I am just sharing my painfuil experience with you. I did the oil cooler seals with pleasure, but I don't have strength to take the transmission off to tackle the main seal.

This is my 8th Mercedes and the newest, but I never had problems like this before. It's a shame to have this type of problems with a 4-5 years old car and 89000 miles on it properly maintained.

Wish you best of luck guys.

Update :
Got home after sending the post above and checked more to figure out the source of my leak.
Well, I took a big seringe and squirted water slowly in different areas of the V.
First I poured some water in the thermostat area ( front of the engine)- surprise... for me... water rushed out right from the bell house. The weep hole on the upper left ( driver side) was dry. I was pretty sure that everything that goes in the V after the oil cooler is istalled get collected between the engine block and cooler and diverted to the left side out of the "V". So I was very wrong by saying that if the weep hole on the left is dry it means oil cooler seals are OK.
Poured more water in the turbo area towards the back of the engine and water dripped in the same area from the inside of the bell house.

What sources of leaks do we have on the upper side of the engine, inside the "V"?
1. oil cooler seals
2. gasket under the turbo piedestal
3. gasket between piedestal and turbo
4. the big 19mm plug on top of the turbo fixture. ( i don't know exactly its main purpose there) - cheked for wetness, no problems.
5.PCV gasket and turbo inlet gasket (leaks there should be very slow and it will take long time to show at the bottom of the engine). Just replaced those gaskets of course as well as all the gaskets needed for the above mentioned items.
4. head gaskets ??? ( any oil passages ... I don't know)
Are there any other sources?

All the gaskets were applied after a very good cleaning of the mating surfaces. Everything was done slowly, i was not in a hurry to fix the car and of course I've done it FOR ME. Bolts were torqued with torque wrench at their specified values. ( thank you Astros... I was lazy to double check myself).
If i would do it again, i have no idea what would I do different ... oh, I know.... probably i would spend another $150 and change the oil cooler too.
Do you think that the cooler can have a hair line crack somewhere that can leak under pressure?

For now i refuse to believe that a less than 5 years old Mercedes car has the main rear seal leaking at 89kmiles

The way the oil drips in my case, can originate from anywhere based on what I just did this evening.

Sorry for my long post.

All the best.