Parts Catalog Accessories Catalog Tech Info Tech Forums
  Search our site:    
 Cart  | Project List | Order Status | Help    

Go Back   PeachParts Mercedes ShopForum > Technical Information and Support > Tech Help

LinkBack Thread Tools Display Modes
Old 04-09-2002, 03:09 PM
420's Avatar
420 420 is offline
Registered User
Join Date: Nov 2001
Location: Georgetown, Ky
Posts: 123
Question W126 transmission or rear differential noise

Hi all.

I’ve got an 89 420SEL with 115,000 miles on it. It’s been in the family since new and it’s mine now.

I’ve noticed what sounds like “gear noise” when driving at 20-25 mph. It’s just a steady “Rrrrrrrrrrrrrrrrrrrrrrrrrr” type sound. Not too loud but noticeable to paranoid, anal retentive freaks like me. It does increase in pitch as the cars speed increases and on the highway at 70mph it’s a very high-pitched whine that fades in and out….(I’m just assuming that the two sounds are related.)

The noise is not affected by engine load, or which gear the car is in. While coasting if I shift to neutral, the noise remains unchanged.

This leads me to believe that the noise is coming from the differential, not the transmission. Would I be correct in this assumption?

I had planed on putting in some 80w140 synthetic gear oil but I just wanted to get some opinions on the subject before I do anything.

73 220D
08 997 C2S
03 Jetta wagon TDi
Reply With Quote
Old 04-09-2002, 03:42 PM
Posts: n/a

Check the rear tires for unusual wear,lumpy or cupped tires will cause noise.
Axle bearings also cause noise when going bad and can sound like a diff problem.
Good luck M.f.
Reply With Quote
Old 04-09-2002, 03:54 PM
Registered User
Join Date: Feb 2002
Location: Bulgaria, Sofia
Posts: 584
Hi, I change my diff before two days. My diff was noisy only when the car was in a gear, when I put it into neutral the noise disappered. So I would guess that it's most probably you'r bearings


190e 2.5-16v
Reply With Quote
Old 04-09-2002, 10:13 PM
amg280's Avatar
Registered User
Join Date: Apr 2002
Location: NY
Posts: 530
I have an 86 420SEL with 208,000 miles (I love it to death) and it has a bad differential in it. I have a good used unit out of a 560 im waiting to put in it. Mine sounds exactly like you describe. At around 80MPH, it gets pretty loud. the pitch on mine will vary with the amount of gas I give it. So when it starts making noise around 70, try feathering the gas and see if it goes away or not. Im guessing you have a bad differential, but like the others say it could be a bad bearing, although if it was that, the noise would be there all the time, and may go away when making a sharp turn. I also fine my bad differential is especially noisy on cold morning when the temp is in the 20's.
Reply With Quote
Old 04-09-2002, 10:28 PM
Join Date: Nov 2001
Location: Cape Cod Massachusetts
Posts: 1,427
Lightbulb Strange sounds from the Rear!

If the noise changes when turning could be the 1/2 shaft constant velocity joints. Turning changes rotational speeds betwen the two sides and if the sound changes could be something like that. If the sound doesn't change then maybe bearings or the differential. Sometimes driving with the windows down along a wall or a barrier can help you hear and locate the sound better as it reflects of the hard surface. Just a thought!
Reply With Quote
Old 04-09-2002, 11:58 PM
Registered User
Join Date: Feb 2002
Location: Fredericksburg VA
Posts: 22
Just a thought-- I had a similar noise in a 190 2.3 turned out to be front wheel bearings. I have a van that has a noisy differential
at certain speeds however when I ease up on the gas the noise becomes too quiet to hear. Constant speed noise kinda makes me think bearings or drive shaft parts.
Reply With Quote


Thread Tools
Display Modes

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Trackbacks are On
Pingbacks are On
Refbacks are On

Similar Threads
Thread Thread Starter Forum Replies Last Post
1987 300 SDL rear end noise jrmurray Diesel Discussion 7 09-15-2008 10:45 AM
Noise coming from rear end please help! yober4u Tech Help 16 11-22-2004 04:40 PM
Noise coming from rear hubs aldedmon Tech Help 4 08-25-2004 09:49 AM
rear suspension noise mbtjc Tech Help 9 01-04-2004 06:24 PM
99 S320 Transmission noise BENZ TEK Tech Help 0 06-10-2003 10:32 PM

All times are GMT -4. The time now is 11:45 PM.

Powered by vBulletin® Version 3.8.7
Copyright ©2000 - 2016, vBulletin Solutions, Inc.
Search Engine Optimization by vBSEO 3.6.0
Copyright 2011 Pelican Parts - Posts may be archived for display on the Peach Parts or Pelican Parts Website -    DMCA Registered Agent Contact Page