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Saved an E350cdi coupe from certain death!

Leng

Member
Joined
Jul 12, 2021
Messages
43
Location
Peterborough UK
Car
2006 CLK 320 CDI, 2011 E350 CDI Coupe
Hi,

I purchased an e350 cdi coupe 2011 in February this year. It has the 265bhp OM642 engine.
The car had faults when I bought it which I will run through. As I do my own work this was not an issue as I planned to do to it what i've done with all Mercedes that I own and have owned which is a full suspension rebuild and any pre-emptive maintenance needed along with any repairs needed.
  • EML light was on (went into limp mode after 5 mins driving)
  • Engine temp gauge wasn't getting up to temperature
  • Knocking noise from the front end
  • Vibration through the car when taking easy corners at motorway speed
  • Vibration when braking
  • Vague, loose, bouncy feeling when taking easy corners at motorway speed
  • General discomfort when driving
  • Oil leak
  • Massive oil consumption
After getting it home and plugging it in the DPF appeared to be causing the issue, ie. it was blocked. I replaced the thermostat as I thought this could be stopping the car doing a regen as it's not getting to temperature but it didn't resolve the DPF issue, the temperature gauge now works fine though.
Next I checked the readings of the DPF sensor which seemed to be working OK. I replaced the sensor with a genuine one anyway as the one I removed was aftermarket, this however was not the fault, the pressure and soot content was still high and a regen would not happen.
While replacing the sensor I sprayed some cleaner into the DPF then ran the engine at idle for 15 mins, after which time a quick check showed the pressure had reduced massively, then 2 mins into a test drive I noticed an increase in RPM while at idle, a lot of smoke and the smell of burning rubber, result! the car was now regenerating on its own, along with this the engine management light went off.
The car now drove fine engine wise so set about accumulating all the parts for all other work I had planned.
When I came to do the oil cooler seal work it quickly became apparent that I had a blown turbo on removal which if neglected could of terminally killed the engine, the car drove fine with no noticable smoke, it did smoke on a regen occasionally but I thought this was oil that had leaked from the oil cooler burning off, the smoke was actually oil from the back of the turbo leaking onto the DPF, the inlet was full of oil.
Ive owned numerous OM642 cars with my current burner at 230,000 still doing 800 miles a week without issue so was always baffled to hear about numerous failures on the later spec engine. After seeing what had happened to mine could it be that the DPF is killing them?
My turbo failure was caused by the blocked DPF allowing excess heat and pressure build up at the back of the turbo blowing the seals, all pipes connecting to the back of the turbo showed signs of excessive heat through colouration.

All work is done now and the car drives perfect, all intakes were cleaned,

20240806_121719.jpg

That is how they looked, all were cleaned along with the inlet manifolds, throttle body, EGR flap and EGR valve, all seals replaced and a full service at the same time.
I also replaced all front end suspension arms, shocks and springs front and rear.
I'm very particular about the way my Mercedes drives and although it drives perfect I've not replaced rear subframe bushes and arms yet so more to come. At the minute I'm enjoying being able to drive the car properly and its an absolute beast!
I was going to do a gearbox service too but after getting a quote from PCS its not worth it as they are very, very reasonably priced so ill be booking in shortly.

I created a spreadsheet to track my costs and what I've actually done and still got left to do, all is green so its all good.

E350 cdi parts list.pngE350 cdi parts list2.png
 
Good job! Hope the car was cheap to purchase.

Was there actually an issue with the oil cooler seals or was it preventative as you had the turbo off?
 
Good job! Hope the car was cheap to purchase.

Was there actually an issue with the oil cooler seals or was it preventative as you had the turbo off?
Hi Teddy,

Thanks, the car was cheap to purchase at the time having the euro 5 engine. I've spent more getting it right than the vehicle cost.
The oil cooler seals had failed and was making a lot of mess,
20240806_121822.jpg

On removal it had the orange seals, now replaced with the purple ones.
The most interesting find was the EGR flap that connects to the throttle body was totally blocked. The opening which was meant to be roughly 2 inch by 1 inch was covered completely by 10mm thick carbon build-up. I was surprised I didn't get an EGR fault flag up.
All has been thoroughly cleaned now with all seals replaced.
 

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