Diagnosing vibration - possible wheel bearing or caliper problem

[Oxfordian]

Hi all,
To safely drive my old C220 CDi to a garage, I need some reassurance and help with a scary problem. The problem is a sort of knocking noise, mostly at the lower front, that is only present when the car is in motion. i.e. issue is not present at rest when the engine is revved.

On starting from cold, it manifests itself after about 2 mins and from 15/20 mph and greater. As the car speeds up, the slow repetitive noise gets louder, and the repetition increases in line with the speed of the car, 'till it's a very constant & loud vibration. Driving a few miles at 30-40 mph is very noisy and unpleasant.

I've discounted engine, gearbox and prop shaft and the discs are not jammed or catching. Since the problem becomes apparent as the car is in motion and the wheels are turning, I'm leaning towards a wheel bearing or caliper issue. But the car has only recently passed an MOT and neither of those was identified as a problem.

So question: would a wheel bearing or caliper issue only show up on a moving vehicle? And has anyone got any other suggestions?

Tks from a befuddled driver!

 

[Mickw212]

did you solve this mate?

 

[Oxfordian]

did you solve this mate?

Hiya,
I did. It was a front offside bearing.
What had me puzzled, was that the car had only recently had an MOT (failed), then an A service & MOT (passed) and I thought the wheel bearing issue would have shown up then. But it was not until the wheels had been turning for a few minutes that the scary vibration etc noise was clearly heard.

The people at MSL Mercedes in Brum did it