Merc 350SL Knocking Sound

DJD

Hi,

I am getting an intermittant knocking noise from the rear wheels of my car. This noise is more pronounced when going around a corner or coming down off a hump in the road (i.e. when the weight is on the rear wheel in question)
Generally the car runs fine for about 10 miles and then the knocking starts. Once it has started it comes and goes over the course of the journey

Does anyone know what may be causing this and how to fix it?

Thanks
Dave

mike65

Sounds most likely to be a worn wheel bearing.

Mike.

8~)

A wheel bearing will hum more so than make a knocking sound and you'll more likely notice a wheel bearing on long sweeping curves in the road.

Start with the simple stuff - check the exhaust mountings. Could be the exhaust is a bit loose and hitting off the body when going over a hump. If that's fine, then start worrying about more expensive things, like driveshafts.

mike65

I dis think about the UJ but reckoned that would be more or less a constant rumble with thunks thrown in for special ocasions.

Mike.

PaulK_CCI

mike65 wrote: »

I dis think about the UJ but reckoned that would be more or less a constant rumble with thunks thrown in for special ocasions.

Mike.

Could be bearing, but I would say more likely a worn drive shaft/CV joint either left or right rear...
I had a similar experience in a Porsche 912 that I bought years and years ago. When I test drove the car myself, it was impeccable, but after I picked it up and had a passenger sitting next to me, each time coming out of corner/roundabout while accelerating, there was this pronounced tac, tac, tac, tac, going faster when the wheels were turning faster. As soon as I was regaining constant speed (so no more excessive pressure on drive train) the sound was gone, and every time I had to accelerate while in a corner, the sound came back again...

Unfortunately Porsche did not sell the joint seperately, but only with the complete drive shaft attached :mad:, but the good thing was, I got it through a Porsche specialist, and he footed the bill :rolleyes:

3ps

I had a similar noise, well more of a regular banging, and it came and went once the car was warm, and it was caused by a sticky caliper.

MercMad

Yeah if the rear brake is sticking it cant cause all sorts of noises. The calipers can stick and give bizzare rumblin noises, though I wouldn't call it a knocking noise, unless it is causing some diff/drive shaft/joint back lash.

You can check after a few miles of driving to see if the wheel is heating up ! It certainly could be a joint though, or some part of the handbrake mechanism. They have seperate handbrake mechanisms inside the disc !

corktina

mother in law tied up in the boot perchance?