Q I have a 2001 Mercedes C320 petrol and it is driving me mad. It has all the symptoms of a wheel bearing issue: there’s a constant ‘woo woo woo’ noise when driving, which increases in volume when turning a corner in the opposite direction, and changes its frequency with speed. The noise is coming from the front offside wheel.
I have changed the inner and outer bearings on the offside, put on a whole new hub and bearing assembly on the nearside (a wheel bolt sheared off in the old hub), and fitted new ARB bushes and drop links. The bearings and hub are all genuine Mercedes parts and came with the appropriate Mercedes green grease. There is no vibration at the steering wheel and no play in the road wheel when jacked up. I don’t have a dial gauge to help me with tightening the G-shaped nut that holds the hub in place, but I adjusted it to be just tight enough according to the instructions in the Haynes manual.
A mechanic friend of mine has also jacked up the car, spun the wheel and felt for play, but he is happy with the way I have fitted the bearing. The only other thing he can think of is tracking or wheel alignment. He also speculated that the new Mercedes-sourced bearings could be at fault; however, they seemed good when fitted. The only thing I didn’t replace was the bearing races, but they were in very good condition and not at all worn or damaged. Mike Mansfield-Corbett
A If I am reading the last paragraph of your letter correctly, you say you have fitted the new taper bearings into the old races fitted into the hub. The bearings are a matched unit and should always be fitted as a complete bearing. If this is the case, then the noise could well be the new bearings against the old race. Unfortunately, after having run the bearings this way, a wear pattern will have begun and the only solution will be to start again with another set of bearings.
If both the roller bearing and race have been fitted as a complete assembly, as you have had the play and fitting checked, the only other possibility is that you are hearing tyre noise. It is not uncommon for tyres to emit such noises and this can be easily checked by swapping the tyres from the front to the rear. If this changes the noise it will confirm this is the problem.
Have A Problem Vehicle? Get In Touch…
If you have a problem vehicle, Car Mechanics has the answer in the shape of technical editor Steve Rothwell. Email your questions firstname.lastname@example.org.