Parts Catalog Accessories Catalog How To Articles Tech Forums
Call Pelican Parts at 888-280-7799
Shopping Cart Cart | Project List | Order Status | Help




Go Back   PeachParts Mercedes ShopForum > Technical Information and Support > Diesel Discussion

Reply
 
LinkBack Thread Tools Display Modes
  #1  
Old 12-11-2017, 03:05 PM
Father Of Giants's Avatar
Registered User
 
Join Date: Feb 2017
Location: Newport News, Virginia
Posts: 836
Rear end clunk during downshift?

It always happens when the car down shifts and is slowing down, I was wondering what could it be?

Diff mount? Diff bushings? Motor mounts? Also you can feel the transmission clunk a bit to when at slow or awkward shifts

There is also a harsh and sudden clunk when going into reverse, it pretty violent too.

I think I have a compounding problems with mounts and bushings.

Also when push comes to shove, what tools do I need for the corresponding jobs? These clunks are driving me crazy.
__________________
1986 Mercedes 300SDL Black - 312,000 miles. Going into retirement soon- Don't forget to grease the screw and threads on the spring compressor.
Reply With Quote
  #2  
Old 12-11-2017, 04:03 PM
Diseasel300's Avatar
Registered User
 
Join Date: May 2016
Location: Texas Hill Country
Posts: 3,163
Slop in the driveline, probably the differential itself. Raise one of the rear wheels so it clears the ground, leave the tranny in park, grab the driveshaft and see if you have some rotational slop.
__________________
'11 Honda Accord EX - "The Daily" 60K
'83 500SL Euro - "The Money Pit" 116K
'86 300SDL - "The Diseasel" 180K
The Diseasel Thread - Everything You Didn't Know You Wanted To Know
Delivery Valve as Source of Nailing Thread
Reply With Quote
  #3  
Old 12-11-2017, 09:03 PM
Father Of Giants's Avatar
Registered User
 
Join Date: Feb 2017
Location: Newport News, Virginia
Posts: 836
Alright, will do that tomorrow morning.
__________________
1986 Mercedes 300SDL Black - 312,000 miles. Going into retirement soon- Don't forget to grease the screw and threads on the spring compressor.
Reply With Quote
  #4  
Old 12-11-2017, 09:10 PM
Father Of Giants's Avatar
Registered User
 
Join Date: Feb 2017
Location: Newport News, Virginia
Posts: 836
Alright, will do that tomorrow morning.
__________________
1986 Mercedes 300SDL Black - 312,000 miles. Going into retirement soon- Don't forget to grease the screw and threads on the spring compressor.
Reply With Quote
  #5  
Old 12-12-2017, 03:47 PM
Registered User
 
Join Date: Feb 2016
Location: North New Jersey
Posts: 261
i had this issue and it turned out they knocked out the vacuum line to the tranny during a valve adjustment.
__________________
Andrew
Montclair, NJ
--------------
1982 300D Turbo
117k
Petrol Blue/Green
Reply With Quote
  #6  
Old 12-13-2017, 05:43 PM
Father Of Giants's Avatar
Registered User
 
Join Date: Feb 2017
Location: Newport News, Virginia
Posts: 836
Ok, it's slop in the driveline, the driveshaft has rotational play.

How do I fix it?
__________________
1986 Mercedes 300SDL Black - 312,000 miles. Going into retirement soon- Don't forget to grease the screw and threads on the spring compressor.
Reply With Quote
  #7  
Old 12-13-2017, 06:53 PM
Diseasel300's Avatar
Registered User
 
Join Date: May 2016
Location: Texas Hill Country
Posts: 3,163
Quote:
Originally Posted by Father Of Giants View Post
How do I fix it?
Live with it until you can't bear it anymore, then buy or rebuild a differential. Making sure your vacuum system to the transmission modulator is *PERFECT* helps a lot.
__________________
'11 Honda Accord EX - "The Daily" 60K
'83 500SL Euro - "The Money Pit" 116K
'86 300SDL - "The Diseasel" 180K
The Diseasel Thread - Everything You Didn't Know You Wanted To Know
Delivery Valve as Source of Nailing Thread
Reply With Quote
  #8  
Old 12-13-2017, 08:03 PM
Father Of Giants's Avatar
Registered User
 
Join Date: Feb 2017
Location: Newport News, Virginia
Posts: 836
Quote:
Originally Posted by Diseasel300 View Post
Live with it until you can't bear it anymore, then buy or rebuild a differential. Making sure your vacuum system to the transmission modulator is *PERFECT* helps a lot.
What parts are needed to rebuild it? Just curious.


Also, how can I replace all the vacuum lines? I don't know which lines.
How do I test the modulator? I have a vacuum gauge in hand.
__________________
1986 Mercedes 300SDL Black - 312,000 miles. Going into retirement soon- Don't forget to grease the screw and threads on the spring compressor.
Reply With Quote
  #9  
Old 12-13-2017, 08:16 PM
Registered User
 
Join Date: Dec 2005
Posts: 2,260
I think you just find if it holds a vacuum ,if it leaks then it needs replacing for the modulator .The rearends are common enough that you might find a good used one at a yard ,never had a rebuilt .I imagine if its coming apart ,new parts added ,going back with new mounting bushings by a mechanic ,$700. and a sandwich
Reply With Quote
  #10  
Old 12-13-2017, 08:18 PM
Diseasel300's Avatar
Registered User
 
Join Date: May 2016
Location: Texas Hill Country
Posts: 3,163
Tee into the black line going to the transmission modulator and go for a drive. At idle and not moving, you should have somewhere around 12-15" of vacuum going to the modulator. Under strong acceleration it should drop to ~5" and at WOT it should drop to 0". If you have good vacuum going to the modulator, there's not a lot you can do but live with it. Rebuilding a differential is not for the faint of heart, it would be a lot easier to source a replacement or have yours rebuilt professionally, especially if the gears are worn.
__________________
'11 Honda Accord EX - "The Daily" 60K
'83 500SL Euro - "The Money Pit" 116K
'86 300SDL - "The Diseasel" 180K
The Diseasel Thread - Everything You Didn't Know You Wanted To Know
Delivery Valve as Source of Nailing Thread
Reply With Quote
  #11  
Old 12-13-2017, 08:37 PM
Registered User
 
Join Date: Dec 2005
Posts: 2,260
Heres a good link to possible answer some differential issues.differentials, gear-ratios and compatibility | Mercedes-Benz turbo
Reply With Quote
  #12  
Old 12-13-2017, 09:42 PM
Father Of Giants's Avatar
Registered User
 
Join Date: Feb 2017
Location: Newport News, Virginia
Posts: 836
Well that's a hard pill to swallow, thanks guys.
__________________
1986 Mercedes 300SDL Black - 312,000 miles. Going into retirement soon- Don't forget to grease the screw and threads on the spring compressor.
Reply With Quote
  #13  
Old 12-14-2017, 12:06 AM
Registered User
 
Join Date: Dec 2005
Posts: 2,260
We get alot of miles on the parts that the factory installed orig., They can still give some miles if babied.The noise of old age, we also will become much like our cars ,old farts.
Reply With Quote
  #14  
Old 12-14-2017, 12:11 AM
Diseasel300's Avatar
Registered User
 
Join Date: May 2016
Location: Texas Hill Country
Posts: 3,163
Quote:
Originally Posted by Father Of Giants View Post
Well that's a hard pill to swallow, thanks guys.
So long as the rear end isn't growling or vibrating, you still have a lot of life left in it. Keep up with the oil changes and let it ride.
__________________
'11 Honda Accord EX - "The Daily" 60K
'83 500SL Euro - "The Money Pit" 116K
'86 300SDL - "The Diseasel" 180K
The Diseasel Thread - Everything You Didn't Know You Wanted To Know
Delivery Valve as Source of Nailing Thread
Reply With Quote
  #15  
Old 12-14-2017, 08:28 AM
Registered User
 
Join Date: Apr 2014
Location: Sweden
Posts: 17
hmm, the clunking might be a lot of different things.
axleshafts, driveshaft or differential, on one occasion a gearbox.

on a w114 with sort of the same issue as you describe it was the differential,
Montefeller’s w114 280CE – 3.69 to 3.07 differential swap | Mercedes-Benz turbo

the thread has video of both diff mounted and play found without dissembling anything, aswell as the second video of what was the issue. Seen that on multiple differentials.

https://www.youtube.com/watch?v=5W3629vkI5k
__________________
----------------------------
daily: w123 om602turbo 5speed 200whp, w115 240d 3.07 differential
mbturbo.com turbo diesels+gassers in oldtimers/classics
Reply With Quote
Reply

Bookmarks

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 On
Trackbacks are On
Pingbacks are On
Refbacks are On




All times are GMT -4. The time now is 08:54 PM.


Powered by vBulletin® Version 3.8.7
Copyright ©2000 - 2018, vBulletin Solutions, Inc.
Search Engine Optimization by vBSEO 3.6.0
Copyright 2018 Pelican Parts LLC - Posts may be archived for display on the Peach Parts or Pelican Parts Website -    DMCA Registered Agent Contact Page