C250CDI (OM651) - Possible boost leak ?

[m.p.rogers]

Hi,

I can't decide if its just in my head, but with the window down, under hard acceleration I'm hearing noticeable wooshing noise at around 2000rpm+ that I'm suspecting is a boost leak, either in one of the intercooler hoses or perhaps the inlet manifold which I understand is a known issue on the OM651 engine. No EML light or noticeable loss in power.

I've booked in with MB to have them look at it and hopefully cover the repair under my extended warranty, however if it turns out to be a split hose or its all in my head, I'll have to pay their diagnostic charge of £174....

Can anyone else with a 250CDI (OM651) confirm if they get a noticeable wooshing sound with the window down under hard acceleration ? Perhaps it's just the turbo and I'm worrying over nothing... ?

Car is a 2014 C250CDI with ~98k on the clock.

Many Thanks
Mark

 

[Tonygw]

Hi Mark

I have the same model car S204 C250CDi with the OM651, I don't hear any wooshing noises under acceleration, just the clattery diesel sounds. But I will have a better listen late.
However I did have a split boost pipe early last year. I noticed a drop in power and eventually the EML came on. It was diagnosed by my local MB specialist who had a smoke machine which helped identify the leak.

The loss of power was intermittent and if I cleared the fault it would be ok for a while but soon come back.

Have you noticed any other effects? It could be a leaking waste gate on the turbo or even a loose pipe but I am sure you would notice a drop in power. They do make some odd noises these om651's sometimes. Mines currently on 104K miles.

Where abouts are you as MB main dealers can be a bit of a rip off for such faults. I didn't pay £174 to get the fault fixed at my local specialist much less and that included the diagnostics. The local indy's are often much better and have full main dealer facilities and knowledge to fix these kinds of issues. Let us know how you get on.

 

[m.p.rogers]

Thanks Tony,

Its Gatwick Mercedes, it did make me wince we they said a flat £174 for 1hrs time to just to look at it.

I did wonder whether I'd be better taking to my local Indy, but if it ends up being something other than hoses, I'll only have to take back to MB and have them carry out the work under my MB warranty.

Perhaps I'll try and have a feel around the hoses this evening, see if I can feel a split as its sounds like I'm getting a noise that your not experiencing.

Many Thanks
Mark

 

[Tonygw]

Let us know how you get on, the split in mine was tiny really and I don't think I would have ever found it without the use of a smoke machine. You had to squeeze the pipe auite a bit for the split to be visible. But you never know you might find its and easy fix and save your self some money. Good luck.

 

[m.p.rogers]

Update for those that are interested.

Car went in to MB today, boost hose had split causing wooshing sound, they also recommend engine and gearbox mounts be changed (and was possibly the cause of split in boost hose), leaking rocker cover gasket, leaking throttle body seal and a couple of other bits - £4k!

Was contemplating writing the car off for a moment, thankfully warranty covering some of it and will get it into an Indy for the rest.

 

[Tonygw]

Wow glad you sorted the noise, mine was about £150 for a new boost hose when mine went, £200 for engine mounts plus couple of hours labour.
Not sure about rocker gasket leak, I would live with that. Are they sure there is a leak at the throttle body? Seems odd as it's diesel and they have injectors on a common rail. Not aware of a throttle body on this engine. Others may know more.

I would go somewhere else lol. But if you have a warranty that's good news.

Anyway thanks for the update. What's the milage on the car out of interest? Engine mounts are advised at around 100k but unlikely to cause a split hose. It's the oil in the pipe that degrades the rubber causing them to fail.

Cheers

 

[m.p.rogers]

Wow glad you sorted the noise, mine was about £150 for a new boost hose when mine went, £200 for engine mounts plus couple of hours labour.
Not sure about rocker gasket leak, I would live with that. Never heard of a leaky throttle cable.

I would go somewhere else lol. But if you have a warranty that's good news.

Anyway thanks for the update. What's the milage on the car out of interest? Engine mounts are advised at around 100k but unlikely to cause a split hose. It's the oil in the pipe that degrades the rubber causing them to fail.

Cheers

Hi Tony,

99k miles, 2014.

Throttle cable was a typo, meant throttle valve seal/gasket just before the intake manifold, leaking were it connects to the plastic pipework. Spoke to an Indy who says they all do to some extent though.

Surprised that MB warranty were willing to cover the engine mounts and boost hose - should be thankful for that at least I guess.

 

[m.p.rogers]

Throttle valve being number 2 on the diagram

 

[Tonygw]

Ah cool thanks for the picture, I actually think mine is leaking a bit there to but its quite a minor leak so I'll keep an eye on things.

Yeah I am surprised MB covered the engine mounts etc but that's great news for you. Did you notice any vibration while idling or driving as that can be a sign they are failing. I am guessing mine might be due to be changed as Ive just clock up 105K miles.

All in all a good result then. But I can see why £4K would make you want to bin the car, glad its survived and hopefully do another 100K,

 

[m.p.rogers]

No, didn't notice any obvious vibration beyond the normal diesel rattles.

Yeah, glad I kept the warranty going, was thinking of canceling it a few months back, glad I didn't as I've made 4 claims now in the past 3 months.

Car still with Mercedes, struggling to get hold of parts from Germany...