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-Benz Forum > Mercedes-Benz Tech Information and Support > Diesel Discussion

Reply
 
LinkBack Thread Tools Display Modes
  #1  
Old 11-09-2013, 09:36 AM
Registered User
 
Join Date: Jul 2004
Location: Barrington, RI
Posts: 5,666
What do I need to know about dampening exhaust resonances?

On my new 98 E300D I had to get some exhaust work done. Specifically, the entire section of pipe from the cat to the muffler was replaced. However, one thing I noticed is that there is a resonance at 900 rpm that was not there before. (The exhaust guy did not know the word "resonance," but he understood when I used the word "vibration." haha)

They are happy to do whatever they need to do to make it right, but claim that I probably need new engine mounts. Personally, I doubt that this is the case, but I will know for certain when my indie looks at the car next week.

Working on the assumption that the mounts are fine, how does one go about eliminating/dampening exhaust resonances and vibrations? The exhaust shop said they could install a flex pipe but that I shouldn't need it since that's not how the car was designed.

Thanks.

__________________
06 E320 CDI "Benson", Platinum Blue, 180k mi, Stage 1 tune
06 E320 CDI "Rutherford", Black, 153k mi, Stage 1 tune
91 300D "Otis", Smoke Silver, 133k mi, wastegate conversion

19 Honda CR-V EX 12k mi
Thirteen other MB's owned and sold
1961 Very Tolerant Wife
Reply With Quote
  #2  
Old 11-09-2013, 10:12 AM
Registered User
 
Join Date: Jul 2001
Posts: 901
I would say that vibration resonance, as distinct from sound resonance, could be fixed by either a flex connection or a different stiffness of mount or perhaps a mass clamped to the pipe somewhere.

A noise resonance can only be fixed by changing the length or diameter of the pipe, basically. In industrial applications there are duct resonators and other tricks to dampen resonance.

Sometimes with a new muffler, the muffler will "break in" as whatever sound damping material inside (if any) settles in, etc.

Rgds,
Chris W.
'99 E300D, 407K
__________________
Objects in closer are mirror than they appear.
Reply With Quote
  #3  
Old 11-09-2013, 10:52 AM
Registered User
 
Join Date: Jul 2004
Location: Barrington, RI
Posts: 5,666
It also makes me wonder what changed that accounts for the resonance. The material? How it's suspended? Where the bends in the pipe occur?
__________________
06 E320 CDI "Benson", Platinum Blue, 180k mi, Stage 1 tune
06 E320 CDI "Rutherford", Black, 153k mi, Stage 1 tune
91 300D "Otis", Smoke Silver, 133k mi, wastegate conversion

19 Honda CR-V EX 12k mi
Thirteen other MB's owned and sold
1961 Very Tolerant Wife
Reply With Quote
  #4  
Old 11-09-2013, 11:38 AM
Registered User
 
Join Date: Jul 2004
Location: Barrington, RI
Posts: 5,666
Well that was simple. Turns out that the heat shield was bent in such a way that it was touching the muffler....and vibrating at 900 rpm. Bent it out of the way, problem solved.

__________________
06 E320 CDI "Benson", Platinum Blue, 180k mi, Stage 1 tune
06 E320 CDI "Rutherford", Black, 153k mi, Stage 1 tune
91 300D "Otis", Smoke Silver, 133k mi, wastegate conversion

19 Honda CR-V EX 12k mi
Thirteen other MB's owned and sold
1961 Very Tolerant Wife
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 05:14 PM.


Powered by vBulletin® Version 3.8.7
Copyright ©2000 - 2021, 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