GLC 220d rear whining

[Foxy25]

Hi,

Has anyone come across a possible issue with what appears to be a rising whine which appears to be either the back axle or transmission and is a constant rise as speed rises and gets noticeable when doing over 40 mph and gradually rises. I know the car will produce some noise form the 4 wheel drive system but this sounds louder than you would expect. Car has 48000 miles and has been serviced in MB on schedule. Thinking it might be time for the gearbox and axle oils to be changed but would appreciate any thoughts.

Uk spec car.
Thanks

 

[Steve@Avantgarde]

Check the tyres. Known for stepping on the inside edges making them look like a 50p piece.

 

[bembo449]

as above , seen this very annoying problem on a good few cars over they years , new tyres will cure it for a while

 

[Foxy25]

Thanks guys, sorry just to clarify, what about the tyres? They are pretty new scorpion tyres run flats. You mean over inflated it tracking or balancing?

just took so photos and a very curious black line around the rear right. It’s all round it.

 

[John Laidlaw]

Tyres look OK to be honest apart from that curious black line, not sure what that is?
I've those tyres on my XC90, I'll have a look in the light!

 

[Foxy25]

I think I’ll bring to MB service as still in warranty. There is a LOT of issues reported with crabbing on run flats and would prefer normal tyres and a can of foam to chance.

 

[Foxy25]

Tyres look OK to be honest apart from that curious black line, not sure what that is?
I've those tyres on my XC90, I'll have a look in the light!

I know there is nothing rubbing of it so it really strange and still 3 / 4 mill on tyres before the thread wear marker.

 

[Steve@Avantgarde]

Run flats are awful tyres, had them on my 2019 C class and as soon as they were bald, off they came for a set of Michelin normal tyres. I had all sorts of issues with tyre skip, noise and an unstable rear of the car when cornering that MB couldn't fix under warranty, they replaced shocks and arms and it was still oversteering excessively when the car hit a bump mid corner. No one believed me when I said it was tyre related. New Michelin non run flats cured the problem and MB paid for new tyres after I created enough with customer services.

The fact they are budget tyres as well says to me you are causing your own problems. The inside edge looks like they are stepping to me. If you run your hand around you should feel a corrugated effect to the tyre.

The cause is a mixture of high negative camber, wide wheels/tyres, high standard tyre pressure and run flat tyres. You'll never really cure the problem, but you can manage it with paying for decent non run flat tyres.

 

[John Laidlaw]

I know there is nothing rubbing of it so it really strange and still 3 / 4 mill on tyres before the thread wear marker.

Nothing on the XC90, apologies though I'd missed the Runflats bit, mine aren't!

 

[John Laidlaw]

Run flats are awful tyres, had them on my 2019 C class and as soon as they were bald, off they came for a set of Michelin normal tyres. I had all sorts of issues with tyre skip, noise and an unstable rear of the car when cornering that MB couldn't fix under warranty, they replaced shocks and arms and it was still oversteering excessively when the car hit a bump mid corner. No one believed me when I said it was tyre related. New Michelin non run flats cured the problem and MB paid for new tyres after I created enough with customer services.

The fact they are budget tyres as well says to me you are causing your own problems. The inside edge looks like they are stepping to me. If you run your hand around you should feel a corrugated effect to the tyre.

The cause is a mixture of high negative camber, wide wheels/tyres, high standard tyre pressure and run flat tyres. You'll never really cure the problem, but you can manage it with paying for decent non run flat tyres.

I wouldn't call Pirelli Scorpions 'Budget' tyres Steve (Not at the price they are for my XC90 certainly!)
Totally agree on the ROF flat tyres, unfortunately my 530d has them, and BMW are notorious for dodging bullets with the X drive system if you stray from the ROF's and recommended brands....

 

[Steve@Avantgarde]

I wouldn't call Pirelli Scorpions 'Budget' tyres Steve (Not at the price they are for my XC90 certainly!)
Totally agree on the ROF flat tyres, unfortunately my 530d has them, and BMW are notorious for dodging bullets with the X drive system if you stray from the ROF's and recommended brands....

My bad..I didn't realise they were pirellis!

My opinion on the rest of it stands!

 

[Foxy25]

Thanks guys. Funny enough driving it today I agree on the handling and corner skips. It does feel unplanted. Yes they are Pirelli and will change for not run flats. I booked it in for Monday with MB for an inspection and test drive and will let you know the results.