ML270 CDI Problem - any advice welcome!

[happypointer]

Hi there! Was hoping that someone might be able to help - or at least advise on the problems (if indeed any of you condier it to be so!) we are haveing with our 52 plate ML270 cdi. Any advice is welcome, I do not know an ENORMOUS amount about engines - so please forgive me for using whatever laymans terms I do!!

We live in SW France and just as we were leaving to head up the country to the ferry the oil light came on - I dived into the local mechanic who topped up the oil and thought nothing more about it. After quite a tough and (as we were going to miss the ferry) fast drive up through France, filled the car up at the last station before the port. Once boarding the ferry I noticed a small vibration, but thought no more of it.

Once on the other side it seemed to me that the car was running a little rough, very noisy. Then a couple of days later, just before heading up the motorway it didn't want to select gear - or at least took it's time doing so. Then once out on the motorway, at about 70 mph it just flat out stalled; luckily near a layby into which I coasted.

I turned the car off and restarted and the problem didn't reoccur and hasn't done so to date, neither has the gear selection issue. I was suitably worried about the car that I took it into our MB dealer in Portsmouth, who hooked it up to the machine and declared that there was nothing wrong with it. They said that the described symptoms could be the Air Mass Indicator but that if there was a fault it hadn't registered in the computer, so I would just have to see. As for the vibration they said that this was being caused by the rubber feet under the air filter box having perished (the vibration seems to be coming from pax side, just fwd of dash). I was unsure if it might have been caused by a nasty tank of diesel - but the drive home through France the car still seemed quite rough - I can't hear the "whistle" of the turbo at all. Today when I went out to start it, the glow plugs light went off as usual, and then came back on for about 30 seconds or so. From reading other threads on this forum I understand that to mean that one or more of the glow plugs has gone and should be replaced immediately, but is there any way that all this might be related? I must say that whilst the car has never been a powerhouse it just doesn't seem to have the power it did pre-problem and is still running quite roughly. Just for information, about 8 weeks have passed since the visit to the MB folks.

Once again I apologise if I am not the most technical - but seeing as MB couldn't find the problem and that the car still isn't seeming to run properly, I was hoping that some kind soul might be able to shed some light!

Kind regards

 

[5pares]

Could well be an injector fault,the tolerences need to be checked,this can be checked on a star by checking injector quantity or measuring the leak off. The glow plug light will not effect the running,not once its warmed up anyway.

 

[television]

And my thoughts are un plug the MAF and try the car.

Just for the record the best place in Portsmouth is Ollie at Prestige Car Srvices and ½ the MB price

 

[kebo57]

Hi fellow ML owner
I have been thinking about this thread but can't sort of offer any help
you say
tough and fast drive up through France
I noticed a small vibration
it didn't want to select gear
at about 70 mph it just flat out stalled
regarding the above your motor is an 02 could be ready for a auto box oil change my ML has done the stall/lost the drive thingy about 25K ago, my box has had about 15 letres of auto fluid through it and its been ok sinse then

through France the car still seemed quite rough
I can't hear the "whistle" of the turbo at all
the car still isn't seeming to run properly
car was running a little rough, very noisy
regarding the above the turbo is operated by The Boost Pressure Transducer via 6mm rubber tube
you can see the turbo operating if you look in the correct place when you rev the engine
our if you remove it then there is no turbo operation
there could be a split in this tube our other pipes in this system the turbo side is fairly complicated to explain about
keep updating this thread
Kevin

 

[stumo]

I have the same car, and a similar problem, so I will list my issues so that it may help you diagnose yours...

Mine sometimes goes into "secret" limp home mode, at which point the engine seems quite rough and no usual turbo noise. I say secret mode because I have a carsoft system and I get no faults displayed, even though it is definately in limp mode and a simple re-start clears the problem. So I currently have no idea why it is happening.

In my limp mode the turbo actuator stopps working and the gearbox stays in (I think) 3rd gear. This could be the cause of the rough running/vibrations you describe as the engine will be running at higher speeds than normal most of the time. Then when you pull away from stopped you really notice the lack of turbo.

 

[happypointer]

Just wanted to thank you all very much for your ideas - at least it gives me somewhere to start. Think I have made a mistake regarding the turbo bit - after writing my post I went outside and listened to the car and although not as loud as I remember it being the "whizz" or "whistle" is still there.

What concerns me the most is the rough running of the car. When pulling away, or even idling at 1500 odd revs there are vibrations throughout the car, almost feeling as if it would be happier revving a touch higher. By vibrations, I mean that the just about everywhere vibrates! It's not just the part I was moaning about just forward to the pax side dash (the bit I was told was the "air box" with perished feet!) It's only the second diesel I have owned, the first being a golf which I have to say was a lovely car - but I never recall it reacting like this due to cold weather etc so I have discounted that. However, the car seems a little happier once warmed up.

I will get my friend Pascale the mechanic to have a look at the auto gearbox oil to make sure it is OK - or indeed to change it if needs be. I wonder if him giving it an oil change and cleaning all the relevant parts might help? PLEASE forgive me if I sound a touch naive, but I know very little and so am rather at your mercy -

Once again my sincere thanks to you all, and to Television, thanks for the Ollie recommendation, will remember that next time I am back in Pompey!

 

[psmart]

The turbo on these cars always spins as the air inlet is restricted, so a certain spin rate is needed to provide the engine with sufficient air. The actual spin rate is calibrated at the factory but can be adjusted (dont go down this path!).

The vibrations can be the engine mountings (mine were replaced 2 years ago, but have gone again with vibration through the car). If the injectors arent firing smoothly, (ie. worn, poor pressure etc), then this just excacerbates the vibration (I can test this by mis-calibrating the injector settings in the ECU, hence knowing its a problem if all injectors are not quite spot-on).

The MAF on this engine doesnt really cause major problems other than poor acceleration, economy etc. Disconnected, the car runs fine, albeit not as quick and thirsty.

 

[pault8084]

I've recently replaced engine mounts which stopped my nasty vibrations.Parts only 50 quid,well worth doing