w124 Major Noise Issue

[snoopy]

When going along I get a "WALALALALALLA" noise. It doesn't change in volume much but the pitch changes. It's as loud as the diesel engine!

It's from the rear, so that's bearings, diff or prop shaft?

Today I jacked up both wheels and had my mam rev the engine while I went under with the camera. The noise was less profound (by a lot to be honest) but was still there.

Also on the camera you can see the wheel, passenger side looks like it's not running true. See if you can spot it. This might be normal.

YouTube - p1020028

 

[Stratman]

Are you near a Mosque?

 

[kwakdonut]

Sounds like either diff or propshaft bearings tbh. Does the sound get less on the over-run or backing off the throttle?

You took a hell of a risk being under there with the car just on jacks!

 

[kwakdonut]

are you near a mosque?

lol!!

 

[Sp!ke]

I can't believe you went under the car like that, supported by a trolly jack with the engine running and in gear and the wheels turning and someone in the drvers seat.


Please read this thread.

http://www.mbclub.co.uk/forums/general-discussion/86212-safe-use-jacks.html

 

[snoopy]

Erm the car was on two 3-tonne stands. Who mentioned a trolley jack!?!

Noise is much more profound in this one. See what I mean?

YouTube - p1020029

 

[snoopy]

Sounds like either diff or propshaft bearings tbh. Does the sound get less on the over-run or backing off the throttle?

You took a hell of a risk being under there with the car just on jacks!

It changes slightly but not greatly.

 

[Sp!ke]

I've just looked again and I stand corrected (it looked like a trolley jack).

I still wouldnt have gone under the car running on stands like that. I wont even be under a car when someone opens the door or is inside.

 

[snoopy]

So ideas so far apart from broken park brake spring, but I really can't see this noise being from that it sounds more bearing like.

The vid inside the car is the one to watch as the noise is much more obvious.

 

[grober]

Sounds like excessive wear in the differential ring and pinion gears to me. Its a Gear Wheel sound rather than Bearings which would be slightly higher pitch?? Could be other gear parts of the diff like the spider gears or slide gears but I think you might get a change in sound on right and left hand corners- if its constant then its the ring and pinion- its possible the pinion bearing is worn allowing excessive clearance? It will quieten up on stands because its not being asked to transfer any torque. Rebuilding a differential requires engineeering experience to set the gear backlash so if the diff is gone your best bet is a breakers yard but make sure you get the same differential as the ratios differ and the flanges to the drive shafts can be different also.

http://www.google.co.uk/imgres?imgu...a=X&ei=bni3TM6IE8aa4AbU3ZjqCQ&ved=0CCkQ9QEwAg

 

[BlackC55]

I've just looked again and I stand corrected (it looked like a trolley jack).

I still wouldnt have gone under the car running on stands like that. I wont even be under a car when someone opens the door or is inside.

It is perfectly safe thing to do as long as the stands are firm and in the correct place.

It is usual practice to test bearing noises in this way.

 

[snoopy]

Sounds like excessive wear in the differential ring and pinion gears to me. Its a Gear Wheel sound rather than Bearings which would be slightly higher pitch?? Could be other gear parts of the diff like the spider gears or slide gears but I think you might get a change in sound on right and left hand corners- if its constant then its the ring and pinion- its possible the pinion bearing is worn allowing excessive clearance? It will quieten up on stands because its not being asked to transfer any torque. Rebuilding a differential requires engineeering experience to set the gear backlash so if the diff is gone your best bet is a breakers yard but make sure you get the same differential as the ratios differ and the flanges to the drive shafts can be different also.

Google Image Result for http://www.factory-servicemanual.com/wp-content/uploads/2009/06/car-differential.jpg

When I was under the car it was very difficult to pin point the noise. I thought it was coming more from the passenger side of the car but not by a lot.

The noise is constant, it's why I doubt that a broken spring could cause it (if it's flapping about). It's an identical noise per speed to boot.

Bigger investigation happening tomorrow. Andrew

 

[kth286]

one of the CV joints ?

 

[snoopy]

It's almost definitely the diff. Gets rather noisy in 5th when up in the air.

Not the wheel bearings or park brake springs - these have been checked.

Prop has play going into the diff, not sure if this is normal.

 

[snoopy]

duplicate deleted

 

[BlackC55]

Play in this area is not normal. Use a long screwdrive to your heat to locate the noise.