W163 front axle noises

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New Member
Apr 1, 2014
NSW, Australia
W163 W168 W203 + racecar
I don't think we're having a good run of luck with the ML270 this week. :rolleyes:

Now we have grinding/moaning/mild howling noises coming from somewhere up front. It's road speed related, not engine speed related. Location is very hard to pick, but most likely front drive. It sounds a bit like a wheel bearing or a front diff bearing or maybe even a diff crown/pinion noise. The car has had 170,000kms of open road driving. Jacking up front wheels and rotating them has told me nothing.

Does the M-Class have any reputation for front diff or wheel bearing problems?
Bumping this to the top again. I still can't locate it. There seems to be a bit of a rhythmic hum to it, probably one cycle per wheel revolution.

I've checked and rotated tyres. Wear patterns were all normal and it's made no difference.

Brake rotors are perfect - even wear, no high spots or glazes or anything like that. Calipers/pads are moving freely.

Half shaft/CV joint noise maybe? (Although no boot damage and no clicking on full lock). Otherwise I'm back to wheel bearings and front diff crown?
My centre bearing is worn and makes a noise that sounds like it's coming from the front. Get a garage to check that if I were you.
As mentioned, Quite likely to be a worn prop shaft centre bearing....But also, Remove the underbody splash shield and check the front propshaft large UJ joint for play, there shouldnt be any, mine was worn and gave a kind of grinding/crunching noise, this joint is not replaceable and necessitates a new propshaft if play is present.
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Thanks for your replies. I'll check them as soon as I feel vaguely fit again. Just did an 1,800km round trip in 40 hours in the race car because the ML270 wasn't safe to take. Now half deaf, with arm cramps, numb bum, sun burn, monoxide poisoning ...
Sorry to jump on this thread but I have a ml270 on a 52 reg and carnt find any front bottom arms anywhere as bush were shocker bolts to has collapsed and don't know were I can get bush or arm euro parts don't stock any in either uk or Germany please help me
Sorry Tony, I really can't help you there. I live in a sleepy seaside village 200 miles from anywhere on the far south coast of NSW. I assume you mean that the lower shock mount is collapsed. If I were in your situation I'd be finding a good engineering shop with a very skilled welder to repair that. Otherwise I think you need to go to a genuine Mercedes dealer or a wrecking yard for the part.

BTW, as the noise problem has worsened it's now clear that it's a front wheel bearing failing. I found a series of fast smooth downhill left-right sweepers near home. The noise difference between left and right turns is pretty obvious. I did check and founds that all the prop shaft joints and bearings are good.
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All fixed now with a new drivers side front wheel bearing. :) It took an apprentice 3 hours to do it, mostly because of the difficulty in pressing out the old bearing.

FWIW it took about 1,000kms of highway driving for the noise to progress from just a vague suspicion of a hum to a clear diagnosis of a failing bearing. At that stage there was a detectable difference between the noise on left and right hand corners and you could also feel the vibration through the steering wheel. It lasted another 500kms after that without any play in the wheel, but it was getting noisy enough to say it wasn't going to hold out much longer.
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