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 > Tech Help

Reply
 
LinkBack Thread Tools Display Modes
  #31  
Old 12-29-2006, 07:34 AM
Parrot of Doom's Avatar
1997 W210 E300TD 243,000
 
Join Date: Mar 2006
Location: Manchester, UK
Posts: 983
Silly question time - do you have mats in your car, and had the mat managed to move up behind the brake pedal and restrict its movement?
Reply With Quote
  #32  
Old 12-29-2006, 11:39 AM
Registered User
 
Join Date: Jun 2006
Location: Southeast
Posts: 1,629
Interesting thought

Quote:
Originally Posted by DrLou View Post
I think there's more to this - and it hasn't been discussed yet here...

First off, my main car (testbed, laboratory, etc.) is a diesel 126, so don't know how much of this applies to your 124. Given that caveat, here goes:

My vacuum pump has never failed, but I understand it may go like this if it ever does: As they start to go, they are known to start dumping engine oil into the brake boost line (the big plastic pipe between the pump and booster body). Because this line has ports which supply vacuum to the shutoff system, EGR, climate control, etc, any number of symptoms may result as this oil creeps into vacuum lines. It isn't hard to imagine that one of these might be an intermittent loss of brake boost. A very common effect is loss of the vacuum shutoff function.

In my case, a small occlusion of 'crud' in one of these ports completely blocked the vacuum shutoff circuit. After cleaning the port, problem solved!

Before getting too crazy with replacing everything: spend 15 minutes, remove this vacuum line, and be sure it's clear.

Lemme know! Lou
Interesting thought. One guy said the vacuum either works or it doesn't, and so far, it's working. Unless he's wrong and it goes down hill little by little.

Thanks,

Jeff
Reply With Quote
  #33  
Old 12-29-2006, 11:40 AM
Registered User
 
Join Date: Jun 2006
Location: Southeast
Posts: 1,629
Definitely not the mat

Quote:
Originally Posted by Parrot of Doom View Post
Silly question time - do you have mats in your car, and had the mat managed to move up behind the brake pedal and restrict its movement?
Thanks for the tip, but nooooo way. Once your brakes go hard and you are basically rolling with no brakes, it ain't the mats. They will at least give when you press down harder.

Jeff
Reply With Quote
  #34  
Old 12-29-2006, 02:38 PM
Registered User
 
Join Date: Jul 2004
Location: York, PA
Posts: 621
Did you or the mechanic change the brake fluid? Do a bleed to make sure there is no air? Just a thought, since when water gets into brake lines it is not ever a good thing and can cause issues like this!
__________________
~Jamie
_________________
2003 Pewter C230K SC C1, C4, C5, C7, heated seats, CD Changer, and 6 Speed. ContiExtremes on the C7's.

1986 190E 2.3 Black, Auto, Mods to come soon.....
Reply With Quote
  #35  
Old 12-29-2006, 04:13 PM
Benz300's Avatar
Benz Enthusiast
 
Join Date: Sep 2003
Posts: 803
some of the "opinions" here in the post have nothing to do with a hard pedal scenario that you posted.
fluid changed, master cylinders, and brake lines should not give you a hard pedal.
Once again, this forum is great if you're not dealing with such important issues as brake failures. but for something this important please do yourself a favor. take a trip to the dealership !
__________________
Whether you think you can or cannot, Either way you're right!. by Henry Ford.
Reply With Quote
  #36  
Old 12-29-2006, 10:30 PM
Registered User
 
Join Date: Jun 2006
Location: Southeast
Posts: 1,629
Brake fluid and dealership repairs

To respond to 2 posts:

1) The brake fluid was changed back in June when I bought the car. No problems until the hard pedal. No leaks, no nothing.

2) As Benz300 said, brakes are not to be fooled with. You don't want to take advice from novices. I'll listen to ideas, but the bottom line rests with my mechanic. Again, I didn't take it to the dealership, not even a MB specialist, but a general mechanic who I think is pretty competent. He drove it after I had the problem, which occured just that one time, and the brakes worked fine for him. Shince he could really see no problem since everything was working fine, he did a best-guess estimate that the problem was the booster, and replaced it. Too bad the problem then happened a 2nd time, just a week after the booster was replaced. So this time, he replaced the hose. Hopefully all will be well.

Jeff
Reply With Quote
  #37  
Old 12-31-2006, 12:12 PM
Hirnbeiss's Avatar
ich fahre, also bin ich
 
Join Date: Mar 2002
Location: South Florida
Posts: 1,640
Just an FYI

Someone mentioned a '68 Chevelle with no power assist. That's a horse of a different color. It would have had drum brakes, which are "self-energizing" (the shoes basically pull themselves against the drums), meaning they didn't require power assist. They just faded easily.
Disc brakes, being squeezed from the sides, are not self-energizing, and require power assist.
Reply With Quote
  #38  
Old 01-02-2007, 12:35 PM
justinperkins's Avatar
I ♥ German Cars
 
Join Date: Sep 2006
Location: Austin
Posts: 1,312
Quote:
Originally Posted by jbach36 View Post
To respond to 2 posts:

1) The brake fluid was changed back in June when I bought the car. No problems until the hard pedal. No leaks, no nothing.

2) As Benz300 said, brakes are not to be fooled with. You don't want to take advice from novices. I'll listen to ideas, but the bottom line rests with my mechanic. Again, I didn't take it to the dealership, not even a MB specialist, but a general mechanic who I think is pretty competent. He drove it after I had the problem, which occured just that one time, and the brakes worked fine for him. Shince he could really see no problem since everything was working fine, he did a best-guess estimate that the problem was the booster, and replaced it. Too bad the problem then happened a 2nd time, just a week after the booster was replaced. So this time, he replaced the hose. Hopefully all will be well.

Jeff
I think you're making a bad choice by taking your Mercedes to a general (non-Mercedes) mechanic. They are special and require a skilled and knowledgeable professional. When somebody doesn't have particular knowledge of your vehicle, it's common problems, etc.., they are just applying what they know from working on other vehicles (American, Japanese) which sometimes works and sometimes doesn't work.

It's been my experience that a general mechanic (non-German specialist) will misdiagnose and do an unsatisfactory job (i.e. create a new problem and/or not fix the original problem).

I love my German cars too much to let any old dude touch 'em. Between living in California and Austin I have only found one shop that I truly trusted. Sadly, that shop was in Sacramento and I no longer live there.
__________________
-justin

1987 300TD, 1987 300TD
2008 R32, 2000 Passat Wagon
Reply With Quote
  #39  
Old 01-09-2007, 10:51 PM
Registered User
 
Join Date: Jun 2006
Location: Southeast
Posts: 1,629
Specialists

Specialists are good, and sometimes less expensive in the long run. But there are other times when I just feel waaaaay hosed. I needed an alignment recently, and the specialist was like, $145. The "general" place, Marietta Alignment, specializes in alignments, just not necessarily MB's. Cost $50. Each has their advantages. In the case of brakes, I had no clue what was wrong. I thought maybe it was an air bubble in the lines or something, and I'd replaced the brake fluid a few months before with that mechanic, so I went back to him. Turns out, it was something more serious.

jeff
Reply With Quote
  #40  
Old 01-10-2007, 12:42 AM
Registered User
 
Join Date: Jan 2002
Posts: 18,355
I've posted two threads with a similar problem. One on the diesel discussion and one on here.
My 77 300d is also losing its power assist. It has vacuum and the boost seems to be consuming vacuum as the brake pedal is pushed since the vacuum guage drops 3 or 4 inches as the pedal is pushed, but there is little to no power assist. In other words, everything appears to be working, but it isn't.
I'd like to know exactly what the problem is.
It doesn't seem to me that the mechanic has given a clear diagnosis of the cause of the failure described in this thread. So far I don't see a clear reason to think the problem was the hose. What was happening with the hose to cause the problem?
__________________
1977 300d 70k--sold 08
1985 300TD 185k+
1984 307d 126k--sold 8/03
1985 409d 65k--sold 06
1984 300SD 315k--daughter's car
1979 300SD 122k--sold 2/11
1999 Fuso FG Expedition Camper
1993 GMC Sierra 6.5 TD 4x4
1982 Bluebird Wanderlodge CAT 3208--Sold 2/13
Reply With Quote
  #41  
Old 01-10-2007, 02:00 AM
compress ignite's Avatar
Drone aspiring to Serfdom
 
Join Date: Feb 2004
Location: 32(degrees) North by 81(degrees) West
Posts: 5,554
Hard Pedal determines NO power assist

If it happens again ...AND the operator survives...New Vacuum Pump.(Assuming
You've replaced the rubber brake lines.)
Reply With Quote
  #42  
Old 01-10-2007, 12:09 PM
Hatterasguy's Avatar
Zero
 
Join Date: Nov 2002
Location: Milford, CT
Posts: 19,306
Quote:
Originally Posted by kerry edwards View Post
I'd like to know exactly what the problem is.
It doesn't seem to me that the mechanic has given a clear diagnosis of the cause of the failure described in this thread. So far I don't see a clear reason to think the problem was the hose. What was happening with the hose to cause the problem?
Because his mechanic doesn't know anything about W124's and is shotgunning parts.
__________________
2017 Chevy Silverado 1500 LTZ
2007 Tiara 3200

"No free man shall ever be debarred the use of arms. The strongest reason for the people to retain the right to keep and bear arms is, as a last resort, to protect themselves against tyranny in government."
-Thomas Jefferson
Reply With Quote
  #43  
Old 01-10-2007, 12:44 PM
Hirnbeiss's Avatar
ich fahre, also bin ich
 
Join Date: Mar 2002
Location: South Florida
Posts: 1,640
The logical assumption

Since gas engines never or seldom have power brake problems that I know of, the problem is most likely due to the diesel-specific components, which are the vacuum pump and (potentially) the vacuum line with check valve.

Ich tippe auf die Pumpe.
Reply With Quote
  #44  
Old 01-10-2007, 12:57 PM
Registered User
 
Join Date: Jan 2002
Posts: 18,355
Quote:
Originally Posted by Hirnbeiss View Post
Since gas engines never or seldom have power brake problems that I know of, the problem is most likely due to the diesel-specific components, which are the vacuum pump and (potentially) the vacuum line with check valve.

Ich tippe auf die Pumpe.
I think this is an important insight.
What about the vacuum pump and its systems could be causing problems if it seems to be producing adequate vacuum? In my case, this seems to be happening.
I will check the check valve.
__________________
1977 300d 70k--sold 08
1985 300TD 185k+
1984 307d 126k--sold 8/03
1985 409d 65k--sold 06
1984 300SD 315k--daughter's car
1979 300SD 122k--sold 2/11
1999 Fuso FG Expedition Camper
1993 GMC Sierra 6.5 TD 4x4
1982 Bluebird Wanderlodge CAT 3208--Sold 2/13
Reply With Quote
  #45  
Old 10-19-2009, 02:07 PM
Registered User
 
Join Date: Nov 2004
Location: TX
Posts: 141
Jbach and Kerry,

I've had this same problem on my W124.

How was it resolved?
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 05:17 PM.


Powered by vBulletin® Version 3.8.7
Copyright ©2000 - 2019, 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