Hey guys

Brand new issue...

After the car has been sitting even for 30 minutes while reversing and turning the wheel sharply left or right I hear and feel a loud metal CLUNK and then never again for the rest of the drive even if reversing. Car otherwise rides fine. Noise seems to be coming from the front.

Any thoughts? Thanks

 

Where do you feel the clunk? Via the steering wheel or via the transmission tunnel?

 

hi,

so it's always when in reverse, and it's been 20 to 30F outside recently and the has to sit for hours up to only a few minutes. When reversing the reversing is smooth on the engine and trans, but when I lock the wheel to the right or left not too too quickly, i hear and feel it in the wheel well or beyond the firewall, not in the steering column.

I feel like it's a strut or shock/airmatic component.

The rest of the ride and subsequent reversing/turning scenarios are mute and solid as a rock as this car always has been.

Seems like the cold brought this on, as I only have 2500 miles on the ODO and baby .. BABY this car...

thanks in advance for your thoughts, it's not something I wanna race off to benz about, but if someone could point in one direction, perhaps I can get a TSB.. I'll check the TSBs by konigster.

 

This is a single "clunk" or repeated during this one travel in reverse?

 

I noticed the same noise occasionally when reversing out of my driveway, but it doesn't repeat if I try to go forward and reverse again....thought it was like the roof noise with the metal and glass flexing....manufacturer's poor use of materials.

 

One single clunk almost felt like a strut was shifting or some suspension part was shifting under a load
Thanks for your input, could not replicate it today

 

I also experience this reproducible clunk noise while turning sharply in my driveway, reverse but also forward, since its colder outside. I have similar noise on my XWD Saab and came to the conclusion that its the fromt summer tires "sliding" on the cold tarmac due to the 4matic system. It feels the same as when i used to put my old cherokee in 4wd lock and tried to turn sharply.

I just installed winter wheels this morning and will report if it still does it. Since the winter tires are softer and more grippy it should go away if my theory is right.

 

Interesting I'll have to take a look at this again. Also I noted that my cold pressure was down to 34 in all corners and increase that to 42 in all corners and I have not been able to reproduce it hopefully you're right it is just the tires thank you.

 

Yes! My 1998 Isuzu rodeo with 4 x 4 would do this while trying to drive on dry terrain and turn sharply

 

sounds to me (I'm not a mechanic though) like the differential, had something similar with my old Audi S4 - was examined by the dealer back then and told that it's normal operation for a car with AWD

 

Goes in line with my theory also... Just went for grocery getting (isnt it what a wagon is for after all?) and it did not do the noise with winter tires on... But driving dynamics is out of the equation for 4-5 months

 

This sounds like a benign issue. I wouldn't worry about it too much but if it really bothers you, the dealership is always an option.

 

Thanks guys... I trust your opinion .. when I'm due for an oil change I'll have to try and reproduce it. I'm lucky to have a great dealership that went to bat for me against MBUSA and got me buybacks for two cars in a row and then got me all my money back (naperville benz)

I'll certainly report back if anything changes -- thank you all

 

What's wrong with your driving dynamics??

 

Assuming these are all 4matics? It can be simple fix, the diff fluid should be replaced after 1st 3k-4k miles. Have dealer drain/replace ALL Differential fluid in your pumpkins.. Happened on many of my 4x4's
The giveaway is it happening during slow sharp turning.. Hope this helps!

And YES different sized tires, wheel bearings, driveshafts, can ALSO be the cause too.. On 2 & 4 wd models..

 

Will do, thanks!

 

Since the coumpound and sideelwall are a lot softer turn in response is a lot less crisp on the dry. Cant wait for first snow (maybe 2-4 inches in the next 48h! Whoo hoo!).

 

Had the wifey drive it in reverse in and out of our horseshoe driveway and I could see exactly what was happening -- as kart mentioned, the front wheels where making the nose where the rubber meets the concrete.. almost like it was skipping a bit... always when she was sharply turning the wheels.

Did not at all sound metallic or like something from the airmatic or the suspension as I had thought initially. It did it once or twice while sharply turning left or right driving in a forwards direction.

Never had this in the warmer weather, it's a whopping 20 degrees outside now, so that must be it.

I never experienced this with the E550 likely because it was a more narrow tire and a different type of 4-matic?

 

I still think that's the front differential, and likely not a problem.

 

What would change it from month to the next?

 

I believe the ambient temp of the differential fluid changes its performance. But I'm not a chemical engineer, or auto tech - so please check with an expert.

Again, I had this happen in my Audi years ago and iirc that's what I heard from them. It never got worse, but was always there in colder temps.

 

Good to know, thanks for your input! I'm glad it's not likely serious based on what you all are saying

 

Not worrying me at all. Completely went away with softer winter coumpound.

 

Just dropped it off at the dealership, will know in a couple days their opinion. Thanks again to all

 

Certain it's minor!