Screeching from front wheel...help!
 

Hi,

I've just purchased a 1988 300D with 139,000 miles on the clock and full service history.

Car was owned by an elderly gentleman who only covered 3000 miles in the last 2 years.

The problem I have identified is that once the car has been running at speed for 15-20 minutes ever so often there is a nasty screech from the front offside wheel which lasts a fraction of a second. This becomes more prolonged until it becomes a constant screech....very loud and sounds like fan belt screech but more metallic. Makes the hair on the back of your neck stand up!!!!!!!

Stopping the car, I jacked it up it see if there was anything obvious, like a stone trapped between pads and disk/rotor and could'nt see anything.

There did'nt appear to be any play in the wheel itself (I thought it could be the bearing) and the wheel rotated fairly freely when spun.

Its worth noting that the screech would disappear if you just tapped the brake pedal whilst driving and would return as soon as you released it.

I also noticed that if the car was left for 10 minutes of so the screech would disappear, but would come back after 10 minutes or so of driving.

Looking through the old invoices that came with the car I noticed that the front wheel bearings had been tightend 3000 miles ago.

So what could this be, glazed brake pads, rusty edges to disks/rotors, non-MB brake pads, bearing collapse??

Any ideas out there?

Cheers

Bearing could be set too tight or starved of grease.

Caliper could be sticking. Is the wheel hot? Do you smell anything?

I noticed that the wheel bolts were very hot when I took them off, but assumed that this was just heat transfer from braking.....no smell

In terms of the bearing, the wheels seemed to rotate freely when I had jacked the car up and when you grabbed the wheel and tried to rock it back and forth there was no movement. I did however, notice some grease oozing out from behind the dust cap....very minor though.

If the bearings are starved of grease can they be re-greased or is it a case of having to fit new bearings as damage will have occured.

Many thanks

(not sure what 'offside wheel' means, passenger side?) Anyway, are you sure it's coming from the wheel and not either the smog pump or the A/C clutch, which will both make the sound you describe when the bearings or clutch starts to fail. Wheel bearings usually just growl when bad, and unless the pads are right down to metal and dragging on the rotor, I've never heard calipers screech like you describe.

Problem cured....due to the lack of use this car had received over the last two years the brake pads had gone very rusty and one of the pads had seized onto the brake disk/rotor and once hot got even worse and caused the very bad screeching noise.

Once cleaned up and a new set of pads installed the problem has gone away thank goodness.

Translation of Offside....Drivers side ......Nearside.....passenger side....sorry for the confusion, must be UK terminology only :rolleyes:

Thanks for returning with the resolution. Unlike most forums, this one's members do this 9/10 times, and everyone benefits...and thanks too for the translation...I can now impress my MG buddy (owns a '53 TD) :p