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 06-10-2012, 04:37 PM
Registered User
 
Join Date: May 2011
Location: Lutz, Fl
Posts: 63
OVR/brake boost failure

haven't drove the car in few months, last week I tried to get it around block just to get things lubed up. Well...

Idles like crap, ABS + ASR lights on, no tach. Hmm... Drives ok, like it was before until Holy @rap, no power boost for brakes! Luckily no one at the intersection, glided through, no casualties

Started to pour (like it would here in Fl) so no trouble shooting possible.

Last night after only 15 minutes on the forum decided to look at OVR. When I bought the car it had no cover on it, so I suspected some issues. Bingo! After wiggling it in its place a bit, it started to buzz. So just for the testing purposes, I jammed piece of cardboard to hold the contacts apart...Success! Idles normally, tacho works, no lights on the dash.

Still troubleshooting the brakes...too hot to work on the car now

Attached Thumbnails
OVR/brake boost failure-ovr.jpg  
Reply With Quote
  #2  
Old 06-10-2012, 04:57 PM
sixto's Avatar
smoke gets in your eyes
 
Join Date: Jun 2000
Location: Eastern TN
Posts: 20,841
Would be nice to know what car you're talking about. Guessing '90s 126 from the picture.

You're not complaining about AC function, tranny shifting or shutting off the engine so it appears there is some vacuum from the engine vacuum pump. Is it an original or updated vacuum pump? Can you cap the brake booster line fitting at the vacuum pump and draw a vacuum at the engine shut-off fitting by the check valve? It'll take a lot of MityVac strokes to evacuate the brake booster.

Sixto
87 300D^2
Reply With Quote
  #3  
Old 06-10-2012, 06:37 PM
Registered User
 
Join Date: May 2011
Location: Lutz, Fl
Posts: 63
Ups, my bad, you are totally right, Sixto

its 87 300 DT, 167K, bought ~ 1 yr ago, vacuum pump seems original. I did cleaned up some of the vacuum lines (blue saucer) due to shifting issues ~ 8 months ago. In february bought a Acura TL, parked the 300 as a spare. Drove it 1-2 a month around the block, did not had any issues until this occurred.

It shifts as before, engine shut-off is w/out hesitation. A/C works.

I will head out to trouble shoot booster vacuum line, than I'll post my findings
Reply With Quote
  #4  
Old 06-10-2012, 07:09 PM
Registered User
 
Join Date: May 2011
Location: Lutz, Fl
Posts: 63
Yup, booster seems kaputt. Drove it around the block - If light throttle is applied, brakes works just fine.

Pulled the vacuum line from the booster fitting - engine idling - nice suction, enough to make mark on the finger (best I can explain w/out gauge). No loss of fluid in the master cylinder, I dont think that is the culprit.

How hard is to replace the freaking thing?
__________________
87 300D sedan rarity with the #14 death stamp SOLD
Reply With Quote
  #5  
Old 06-10-2012, 07:35 PM
Registered User
 
Join Date: Dec 2007
Location: New Zealand
Posts: 40
Quote:
Originally Posted by ZRatedDog View Post
haven't drove the car in few months, last week I tried to get it around block just to get things lubed up. Well...

Idles like crap, ABS + ASR lights on, no tach. Hmm... Drives ok, like it was before until Holy @rap, no power boost for brakes! Luckily no one at the intersection, glided through, no casualties

Started to pour (like it would here in Fl) so no trouble shooting possible.

Last night after only 15 minutes on the forum decided to look at OVR. When I bought the car it had no cover on it, so I suspected some issues. Bingo! After wiggling it in its place a bit, it started to buzz. So just for the testing purposes, I jammed piece of cardboard to hold the contacts apart...Success! Idles normally, tacho works, no lights on the dash.

Still troubleshooting the brakes...too hot to work on the car now

The OVP protects the ABS, and many other delicate parts !
So REPLACE it, [jamming a piece of plastic ! wont fix it !!]
Reply With Quote
  #6  
Old 06-10-2012, 08:55 PM
Registered User
 
Join Date: May 2011
Location: Lutz, Fl
Posts: 63
Quote:
Originally Posted by maska View Post
The OVP protects the ABS, and many other delicate parts !
So REPLACE it, [jamming a piece of plastic ! wont fix it !!]
oh I will, that was just for testing purpose
__________________
87 300D sedan rarity with the #14 death stamp SOLD
Reply With Quote
  #7  
Old 06-11-2012, 08:20 PM
Registered User
 
Join Date: Dec 2007
Location: New Zealand
Posts: 40

Thats good! When people make statments like that; They Frighten the S***t out of Me

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 10:55 AM.


Powered by vBulletin® Version 3.8.7
Copyright ©2000 - 2024, vBulletin Solutions, Inc.
Search Engine Optimization by vBSEO 3.6.0
Copyright 2024 Pelican Parts, LLC - Posts may be archived for display on the Peach Parts or Pelican Parts Website -    DMCA Registered Agent Contact Page