Differential or Wheel Bearings

[irrogue]

Hi guys. I drive a c230 Coupe 2005 Model, and while ago I started noticing a noise from the back of the car as soon as I hit 80 km/h and then at 100km/h, then it disappear. ( Maybe driving away from the sound ) I knew I had a cracked rimm at the back (Pot Holes in South Africa) so I straightened both back wheels and welded the cracked one, added some new tires as well because if the wheel is buckled/bend it will still make a noise if the tires is worn. Booooya guess what the noise is still there. We drained the oil of the rear Diff and the oil was a heavy black luckily not like syrup added new oil and the noise was still there. What is the next step, I have a new Rear Differential lined up but the question is do I first try the wheel bearing route or the differential. I will highly appreciate any advice from any one that had some sound issues from the back of the car. I tried to look for some rear differential posts but there is only Oil Change DIY Thx Guys

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[Glyn M Ruck]

I have to ask the obvious question. Are you running Continental tyres on the car? Especially Sport Contact 2 or 3. They always make a noise on this Chassis & sound just like a wheel bearing that is failing. As they get older & feather & cup a little they will make even more noise.

Known quiet tyres on the W203 are Michelin Pilot Exalto PE2, Michelin PS2 & Yokohama AVS db2.

If you damaged a rim you might have a suspect wheelbearing but worry about tyres first. Also check Flex discs, UJ & spline & center hanger bearing on the propshaft & make sure the CV joint boots are in good condition on the rear driveshafts.

Good luck!

BTW - Welcome

[irrogue]

Hi Glyn

Thx for the quick reply, really appreciate it.

As for tyres I did put on brand spankin new ones on, but not any of the above mentioned ones, the tires don't even have a 100 km on them and the noise is still there, I highly doubt it can be the tires or the wheels.

I spoke to a mechanic today, will take it in and also advise him what you added what the problem might be.

Will give an update soon.

Cheers

[Glyn M Ruck]

You might be surprised. Any tyre with big blocks in the tread is trouble with the W203's because of hard suspension bushings. Tyres need to be the right compound, tread & carcass construction with unbroken radial tread bands. (apart from a few sipes)

If it is the diff there are usually good tell tale signs. The pinion bearings loose preload and the noise it makes will change substantially between throttle on & trailing throttle (throttle off). Try this & report.

If the diff was failing you should also see abnormal wear debris on the magnetic plug (if your car has a magnetic plug - Benz left them off some models). Benz runs low friction bearings on the pinion shaft & they can't tolerate any wear debris in the oil.

Good luck!

ps Continental tyres are noisy from new on these cars & some other brands.

[phister]

Any chance you can video the noise. Sounds more like a suspension or bearing issue as glyn said. But tires really do make noise depending on compound and design. Only conti i know that are good for our cars is the dws but they are an all season tire. After hitting the the pothole did you check all the components of the suspension? Control arms, bushings, sway bar, etc. Make sure none are bent.

[irrogue]

Hi there guys.

Concerning the question that Glyn asked about when releasing the throttle when the sound is on its best. Glynn the sound does not differ when releasing the throttle it stays the same until say 65 then it is normal and no sound. But one thing I noticed is when on the lets say 80 km/h when the sound is its worse and I swerve heavy right it is like the sound disappeared.

Phister thanks for the reply I will try to record the sound, the problem is you kinda hit alot of potholes sudden inclines on the road as they are busy with road works so there is no specific one that I can recall, but the noise sometimes is horrifying when hitting one.

Thx guys

Will give an update soon from the Mechanic.

[Glyn M Ruck]

It's unlikely a diff problem then. It's tyres or wheel bearing if swerving changes the noise unless a subframe bush or rubber is badly worn on the rear.

Swerving the car should not increase the load on a diff side or carrier bearing either because one end of the rear drive shafts has a plunging CV joint on it.

[irrogue]

Hi Glynn

We are replacing the wheel bearings tomorrow will give an update on the situation, thx for all the help.

Cheers

Regards

Stef

[irrogue]

Hey guys go this resolved.

The bearings rusted onto the hubs, some stealership did not do their work.

Replaced hubs and bearings, driving super quite now

Cheers thx for all the advice.

Regards

Stef

[Glyn M Ruck]

Pleased it's fixed & you did not have to mess with the diff!

[irrogue]

Changed the wheel bearings last time, and the noise was gone, now that same noise is back.

Any advice you can give on this matter, the wheel bearings could not have gone again could they?

Warm Regards