Noisey diffs

[SomethingRattling]

Busy week so far with my C240 (W202 2000yr). First in the body shop for a bit of touch up on the rusty wheel arches and tailgate, this is becoming an annual event due to the water based brittle paint problem though £175 pa is a small price to pay to keep it looking good. Fitted a replacement window regulator (OS Rear) bought for £55+VAT from Charlton Auto Parts (www.charltonautoparts.co.uk). Still to fit rear discs and pads, discs from mercman £20+delivery and break pads all round (Halfords Front £27 rear £47 Gulp!). So all looking good except for the whining, no the wifes away this weekend, so possibly the diffs I think? I have read a lot of entries in the forum relating to whining noises that could possibly be attributed to wheel bearings, breaks, propshaft couplings etc. So before buying anything I wanted to establish where the noise was coming from. So I bought a pair of axle stands from halfords (£9.99 the pair) and wheel chocks (£4.99 for 2) placed the chocks under the front wheels jacked the rear up using the standard MB jack and slipped the axle stands pretty much under swing arm just below the suspension spring (having removed the plastic cover) did this on both sides. The car was facing the garage which is full of car boot junk, so I thought was expendable if the car fell off the stands! Made sure the dog, kids and every body was well clear of the vehicle. Pushed the vehicle a few times to ensure was stable then started the engine. Boy! did the traction control bitch! but never the less I was able to wedge the accelerator enough (gradual build up) for the whining noise to be heard I guess about 30mph?. Next using a large carboard tube, about 4 ft long, I was able to lie down at the side and rear of the car and listen through the tube (directional hearing) and YES the whining was definatly louder at the diffs! Now I did ask about replacing various parts of the diff, crown pinion, bearings etc. but it was pointed out that due to tight tolerances and special tools it would probably be best to find a differential specialist. But now having been able to look under the vehicle I notice that the propshaft joint and drive shaft joints look fairly straight forward to disconnect and a replacement of the unit may be easier? so my questions are:

Is the replacement of the diffs fairly straight forward in this manner?

If so the can anyone tell me how to identify the gear ratio?

PS I have had the oil replaced in the diffs but made no difference to the whining.

 

[television]

The whining is the pinion bearing that has gone, this means to replace it the whole diff has to be dismantled, better done with some understanding of bearing mesh, or you take the whole thing off and have the job done by a specialist. The whole thing is fairly easy to take out. What do you think.

Malcolm

 

[benzburner]

my old a4 quattro had a leaky, whiny rear diff and i was told that basically, diff repair was a "very specialised job" and that even if you could identify the dicky parts and replace them, the diff would probably never be right again. even if all the settings and tolerances were set correctly. therefore, the best thing to do is find a complete relacement and do the old switcheroo.

 

[SomethingRattling]

As you say the whole unit appears to be fairly straight forward to remove, so would it make sense to buy another second hand unit from mercman and fit this? I know its a risk as the one I buy may also whine but so far the one thats in at present had done 170k which is high for the age of the car so I'm hoping a secondhand unit may have done less mileage and stands a chance of improving things. I read on this forum that a secondhand unit can be picked up for about £250. But having mentioned to mercman that I may be looking for a unit I was told I would need to find the gear ratio. Do you think its worth swapping the entire unit and if so would you know how I can find the gear ratio? Failing all of that could you recommend a specialist in the Berkshire area.

 

[television]

To find a ratio you will have to go through all the 202 cars.'
http://www.detali.ru/cat/oem_mb0.asp?TP=1


malcolm

 

[SomethingRattling]

I have looked at the parts listings for all the c240's 202.XX. Would it be safe to say that the Chassis number pretty much idendifies which is the correct PN and GR. My chassis number is WDB20286F940713 and it seems to break down to 'WDB' Plant of manufacture '20286' catalogue reference 202.086 and F940713 Date of manufacture which works out to 1:3.67 ratio?

 

[SomethingRattling]

Sorry thats the VIN Number and should read WDB202862F940713.

 

[Sprint'n'Go]

would you know how I can find the gear ratio?

I dont know if it is the same for the passenger cars but, On the sprinter vans the final drive ratio appears on the vin plate/sticker. This is where all the info about axle loadings, paint code, etc appears. If the diff ratio is there it will look something like i=3.67. let us know if it is there so I can file this info away for future referance.

 

[SomethingRattling]

Having nothing better to do I just had a look at the 3 x VIN plates stickers (Door, window and Engine) unfortunately nothing seems to identify the ratio as you suggested. Just as a matter of interest you listed as an example i = 3.67 should that be 1:3.67 or 1 to 3.67 ratio? Thanks for the tip though I did find the model number M 800 on looking this time which has helped me further identify it in the catalogue.

 

[Bolide]

While it's on the axle stands put it in neutral, spin the prop 10 times and count the wheel rotation

Prop turns
------------ = axle ratio
Axle turns


Nick Froome
www.w124.co.uk

 

[SomethingRattling]

That is so obvious its brilliant! It's of the axle stands at present but would I be able to jack the one wheel of the ground and rotate the wheel whilst in neutral and count the prop turns? Being differential to the stationary wheel would I expect to find double the ratio from the single wheel?