Drive train wear on ML270CDI AUTO

[Neil Johnson]

Dear all

I have been the prowd owner of two ML270CDIs (both Automatic) but my latest acqusition seems to have developed a drive train fault . This manifests itself as a jolting effect (snatching) from a standing start on in slow moving traffic sometimes the effect is very pronounced. Has anyone else had this experience and reported it to MB UK ?

 

[panason1c]

Sounds like a transmission fault to me.....i would check the g/box fluid level first, it could be too low.

What year/mileage?........might also benefit from a transmission oil and filter change.

 

[Neil Johnson]

Transmission problem

Thanks for your thoughts - will follow up with MB

 

[RichHammond]

Yes I have this problem with mine its just started, more noticable in slow moving traffic when I initially accelerate and decelarate, im going to see if it gets worse over the coming weeks, its under warrantly for 1 year so hopefully will get it sorted with MB.

 

[RichHammond]

In addition forgot to mention, when I get up to speeds of 30MPH onwards I can hear a humming noise from underneath the car somewhere which increases in tone when the car increases in speed , its only done 29,000 mls any ideas?

 

[Blobcat]

In addition forgot to mention, when I get up to speeds of 30MPH onwards I can hear a humming noise from underneath the car somewhere which increases in tone when the car increases in speed , its only done 29,000 mls any ideas?

Could be caused by differences in your tyres. With 4x4's you really need to have all the tyres the same size otherwise the transmission 'loads up'. This can wear out the drive train.

 

[RichHammond]

Thankyou for the advice, the tyres are the same size and have approximately the same wear, perhaps in the past before I bought it they have been mixed and caused the wear on the drive chain?. Ill let it progress and then speak to MB. Again thankyou

 

[psmart]

Hi Richard,

Ive had an MY2001 ML270cdi Auto since new and it has jolted similar to what you describe from new. Coming from a Grand Cherokee, which also jolted when you engaged gear (manual box), I put it down to 2 problems, 4wd takeup and accelerator design fault.

Basically, if Im trying to hover in a traffic jam/slow speed, pressing the accelerator, the car will jolt (noticeable clunk). If I hard accelerate, then no jolting!

Could be, your latest acquisition and mine have a accelerator design fault, or an ECU fault! I wish I hadnt read your post now, as Im going to be bugged by it and no doubt take the accelerator pedal apart

Ive not had any trouble with any other part of the car, tyres, drivetrain etc, and had 2 tyres which have been way different in tread to the other two for best part of 15-20,000 miles!

ps) Just had a 2nd thought, looking on the USA forums, there have been problems with transfer cases, which only last 40,000 miles due to a design fault on earlier ML's.

 

[panason1c]

Hi Richard,

Ive had an MY2001 ML270cdi Auto since new and it has jolted similar to what you describe from new. Coming from a Grand Cherokee, which also jolted when you engaged gear (manual box), I put it down to 2 problems, 4wd takeup and accelerator design fault.

Basically, if Im trying to hover in a traffic jam/slow speed, pressing the accelerator, the car will jolt (noticeable clunk). If I hard accelerate, then no jolting!

Could be, your latest acquisition and mine have a accelerator design fault, or an ECU fault! I wish I hadnt read your post now, as Im going to be bugged by it and no doubt take the accelerator pedal apart

Regarding the accelerator cable 'notchiness', this is a problem that seems to be present on all ML's, I complained to my dealer about a year ago who said 'they are all like that' he invited me to check out a showroom ML and true enough, it was just as 'notchy' as mine!.......I found that by removing one of the accelerator return springs, the one which is located under the bonnet on the n/s next to the bulkhead and is connected to the potentiometer (NOT the spring inside the car at the pedal end) totally removed the notchy travel completely and made the car much smoother to drive especially when pulling away in slow moving traffic. It takes seconds to remove....just un-hook it.

 

[psmart]

Thanx Panason1c, will give it a go once it stops raining :sad:

 

[RichHammond]

Many thanks blobcat, psmart and panason1c, this has but my mind at rest alittle if they are all like this. Any ideas re the buzzing/humming noise from underneath somewhere it increases with speed and is heard especially when going around a left hand bend? regards.

 

[johnmc]

Hi Rich,
The buzzing noise could be a wheel bearing, worth taking a look. Just a thought from faults on different cars that I've owned. The symptoms sound similar. Both my Mercs have had occassional snatch on the transmission. I'd imagine the diesel could be worse with the higher torque.

On the tread depths, I'd read an article that suggested that 4 x 4 tyres on different ends of the same axle should be kept within 1mm of each other. If not then the result would be accelerated wear of the transfer box and differentials. They didn't say over what mileage, so not that useful!

Good luck!
John

 

[RichHammond]

Thanks johnmc this sounds good advice, ill book it in at MB and let them have alook, many thanks Richard

 

[psmart]

I agree with johnmc on that one, after experiencing 4 wheel bearing burn out, 2 front disc burnout, 4 pads burnout and 4 new tyres of my Fiat Seicento shuttle car which goes behind the motorhome on an A-Frame (A-Frame had a faulty brake cable!). After all was replaced, either one of the new bearings was faulty, or Leeds roads were to blame, but once you got upto 30mph you had a increasing pitch huming noise, which worsened when cornering. Could be your ML has seen a few potholes, which can take bearings out! Easy and cheap to replace on a Seicento, but an ML !!!

 

[RichHammond]

Thankyou, still under warranty with MB so very cheap to replace, he he

 

[Blobcat]

Normal wear and tear not covered under warranty, so I would not start to laugh until you are out of the door of the dealers

 

[RichHammond]

All items including servicable are included in the first 3 months of purchase after that most are included for 1 year. If not they can have it back within the first month of purchase, still laughing, he,he,he.

 

[oigle]

Notchy accelerator cable

Regarding the accelerator cable 'notchiness', this is a problem that seems to be present on all ML's, I complained to my dealer about a year ago who said 'they are all like that' he invited me to check out a showroom ML and true enough, it was just as 'notchy' as mine!.......I found that by removing one of the accelerator return springs, the one which is located under the bonnet on the n/s next to the bulkhead and is connected to the potentiometer (NOT the spring inside the car at the pedal end) totally removed the notchy travel completely and made the car much smoother to drive especially when pulling away in slow moving traffic. It takes seconds to remove....just un-hook it.

Sorry but I don't agree with the above.
I have had this problem with my ML270 in Oz. Took it back to dealer - they lubricated the cable with a special silicone grease. Temporarily helped - problem returned. Next visit - they replaced the cable. Still no good. Lubricated the new one - still no good. Tried a number of different return spring scenarios. They helped a bit but problem still was there. Asked for old cable back from the MB warranty store - gave it back to me after neccessary time held in warranty. Examined it carefully. Found that inner cable is coated in a nylon material and the inside of the outer one is also covered in a similar material. Ever rubbed 2 nylon covered surfaces together? They stick - particularly when hot!! Dismantled the cable and replaced the inner with a new uncoated woven stainless steel cable. Had to make up new ends of course. Didn't bother lubricating it as that just attracts dust etc. Installed it and the problem is history. Took it back to MB for them to test drive it - they said they have never felt such a smooth cable in an ML!! They also added that they are unfortunately not permitted to do any such modifications. They have referred a couple of customers to me since and I have been able to fix their problems too. I have done 20000km in mine since the "fix" and it remains perfect. Cost here in Oz dollars about $100 including labour to R and R the cable. That is only about 40 pounds. Worth it for the driving pleasure. I guarantee it.

 

[panason1c]

"Sorry but I don't agree with the above"
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Not sure with what you dont agree with.....

Firstly....Your post confirms (as i stated) that this is a problem with ALL ML's.......

Secondly....That removing the aforementioned return spring has resulted in my accelerator operation being smooth with no hint of notchiness.....(I should mention that apart from the return spring fitted at the 'pedal' which will be left in place, the potentiometer also has a return spring built into it)

It appears to me that we have both found a solution to the problem albeit via different methods.

 

[oigle]

Not sure with what you dont agree with.....

Sorry Panasonic - I wasn't specific enough. I agree it is an inherent problem with all ML's. My MB dealer as much as admitted that. It is very much a design fault. I understood that you have managed to remedy your individual problem. I hope that it remains a permanent fix for you. I tried the same thing myself, as I stated, with less than perfect results. The notchiness reduced but didn't disappear and the throttle resistance became too light, causing unwanted throttle movement on rough surfaced roads - couldn't keep a steady throttle. I tried increasing the spring tension at the pedal to compensate, but could never find a satisfactory result. I fear that many other people will also find that it does not give good enough results. My fix rectifies the problem properly - it gets to the cause. Perhaps, if members tried your easier fix and still weren't happy, then they have my method to fall back on.
I wonder if the same problem exists on other MB models. I imagine the same design of cable is probably used elsewhere. Sometimes one wonders about the engineers who design such things.