[W126 Coupe] Rear End Thumpety-Thump & O2 Sensor Readings

[Jason Mavris]

If you have the self leveling suspension, is the rubber donuts at the top of the shock mounts.  They are compressed and when you hit a bump only bump your heard the shocks clucking at the top.  Your problem sounds just like mine, I too thought it was the exhaust until someone pointed out its most likely the rubber mounts on the top of the rear shock.  There are 4 total.  1 upper and 1 lower.   The problem as you said was minor in the early stages then it got worse as time went on.  
I changed mine problems been gone ever since.   And it only did it when you hit a bump. 


Jason 
  ----- Original Message ----- 
  From: Markus Meyer 
  To: Mercedes Coupes Mailing Lists 
  Sent: Monday, March 03, 2008 7:20 PM
  Subject: Re: [W126 Coupe] Rear End Thumpety-Thump & O2 Sensor Readings


  For the rear end issues, have your checked your sway bar links?

  Not sure on the 02 sensor...

  Markus Meyer
  mfm at meyerprobateproperties.com
  www.meyerprobateproperties.com
  Meyer Probate & Properties, LLC
  484-919-9762




    -------- Original Message --------
    Subject: [W126 Coupe]  Rear End Thumpety-Thump & O2 Sensor Readings
    From: Alexander Hochhausl <plustech at optonline.net>
    Date: Mon, March 03, 2008 7:17 pm
    To: 'Mercedes Coupes Mailing Lists' <mbcoupes at mbcoupes.com>


    I have a strange development. Every time I leave a light I get a thumping (pretty much the same, but not relative to speed/duration of acceleration) from the rear. I thought it was exhaust related - like the muffler hitting the body. But I don't see evidence of that - all seems to hang clear. I don't feel it in the drive train (if it were a joint or something) all runs smooth. Does it for 1-2 seconds, then is gone. It's been getting steadily more pronounced. I figure eventually something will fall off - that will solve the mystery. Definitely not tire related - just got new ones.

    Second - does anyone know what the "normal" voltage reading for the O2 sensor should be? I can't find it in the service manual I have. I recently noticed a decrease in the normal vacuum while driving - Idle is fine, but driving I need slightly more throttle than normal. I've eliminated vacuum leaks (unless my EGR valve is not shutting) so my suspicion is the O2 sensor is reading "rich" resulting in over compensating on the lean side of the curve. Any thoughts anyone?


    Thank You,



    Alexander Hochhausl, PE

    Tel: 516-909-3794

    '89 560 SEC 

    '81 380 SLC (sold - tears)




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