Brake system failure 1974 450SEL - Mercedes-Benz Forum

 
LinkBack Thread Tools Display Modes
post #1 of 10 (permalink) Old 09-27-2009, 12:27 PM Thread Starter
BenzWorld Junior Member
 
Date registered: Sep 2009
Posts: 8
Mentioned: 0 Post(s)
Quoted: 0 Post(s)
(Thread Starter)
Brake system failure 1974 450SEL

Can anyone tell me why my brake pedal goes to the floor after a day of driving? My mechanic replaced the master cylinder twice, no fluid leaking, etc.

He thinks it has something to do with heat off the manifold?

We could sure use some help.
St. Lucie Appraisal is offline  
Sponsored Links
Advertisement
 
post #2 of 10 (permalink) Old 09-27-2009, 10:05 PM
BenzWorld Elite
 
wbain's Avatar
 
Date registered: Dec 2003
Vehicle: 1965 220S, 1999 Volvo V70 (wagon), 2006 Ford Crown Vic Police Interceptor, 72 350SL 4 Speed
Location: Near Manassas Va.
Posts: 1,830
Mentioned: 0 Post(s)
Quoted: 3 Post(s)
You and you're mechanic will have to check all the brake lines, flexible hoses and calipers for leaks.

Near Manassas Va. '65 220S, 2006 Ford Crown Victoria Police Interceptor, '99 Volvo V70, '72 350SL 4 speed

Not part of the in-crowd since 1952. It's BRAKES not breaks. You break a bone, use brakes to stop your car. /rant

http://www.megamanual.com/index.html
http://www.bgsoflex.com/megasquirt.html
wbain is offline  
post #3 of 10 (permalink) Old 09-28-2009, 06:15 AM Thread Starter
BenzWorld Junior Member
 
Date registered: Sep 2009
Posts: 8
Mentioned: 0 Post(s)
Quoted: 0 Post(s)
(Thread Starter)
There are no leaks anywhere.

Could there be some sort of slave cylinder or secondary cylinder that's failing?
St. Lucie Appraisal is offline  
post #4 of 10 (permalink) Old 09-28-2009, 08:09 AM
BenzWorld Elite
 
flyboyike's Avatar
 
Date registered: May 2003
Vehicle: 2012 Focus SE
Location: Ormond Beach, FL
Posts: 7,699
Mentioned: 1 Post(s)
Quoted: 68 Post(s)
How's your booster?

Felicita e un bicchiere di vino con un panino.
flyboyike is offline  
post #5 of 10 (permalink) Old 09-28-2009, 10:19 AM Thread Starter
BenzWorld Junior Member
 
Date registered: Sep 2009
Posts: 8
Mentioned: 0 Post(s)
Quoted: 0 Post(s)
(Thread Starter)
If I lose vacuum to the booster it will be a hard pedal, right? Mechanic does not think it's a booster. The fluid is topped off, no leaks. Is there a dump valve?
St. Lucie Appraisal is offline  
post #6 of 10 (permalink) Old 09-28-2009, 11:58 AM
BenzWorld Elite
 
flyboyike's Avatar
 
Date registered: May 2003
Vehicle: 2012 Focus SE
Location: Ormond Beach, FL
Posts: 7,699
Mentioned: 1 Post(s)
Quoted: 68 Post(s)
Quote:
Originally Posted by St. Lucie Appraisal View Post
If I lose vacuum to the booster it will be a hard pedal, right?
What if you lose the diaphragm in the booster?

Felicita e un bicchiere di vino con un panino.
flyboyike is offline  
post #7 of 10 (permalink) Old 09-28-2009, 11:25 PM
BenzWorld Elite
 
wbain's Avatar
 
Date registered: Dec 2003
Vehicle: 1965 220S, 1999 Volvo V70 (wagon), 2006 Ford Crown Vic Police Interceptor, 72 350SL 4 Speed
Location: Near Manassas Va.
Posts: 1,830
Mentioned: 0 Post(s)
Quoted: 3 Post(s)
Has all the brake fluid been changed? Brake fluid absorbs water and contaminated brake fluid has a lower boiling point.

Near Manassas Va. '65 220S, 2006 Ford Crown Victoria Police Interceptor, '99 Volvo V70, '72 350SL 4 speed

Not part of the in-crowd since 1952. It's BRAKES not breaks. You break a bone, use brakes to stop your car. /rant

http://www.megamanual.com/index.html
http://www.bgsoflex.com/megasquirt.html
wbain is offline  
post #8 of 10 (permalink) Old 09-29-2009, 04:44 AM Thread Starter
BenzWorld Junior Member
 
Date registered: Sep 2009
Posts: 8
Mentioned: 0 Post(s)
Quoted: 0 Post(s)
(Thread Starter)
May I ask if there is any difference in appearance once the brake fluid absorbs water, similar to oil and water, perhaps?
St. Lucie Appraisal is offline  
post #9 of 10 (permalink) Old 09-29-2009, 10:13 AM Thread Starter
BenzWorld Junior Member
 
Date registered: Sep 2009
Posts: 8
Mentioned: 0 Post(s)
Quoted: 0 Post(s)
(Thread Starter)
To update you, the car has brakes now. Could be that the fluid, diaphragm or whatever has cooled off.

Perhaps a different brake fluid? DOT 3 in there now I believe.
St. Lucie Appraisal is offline  
post #10 of 10 (permalink) Old 10-06-2009, 03:57 PM
BenzWorld Junior Member
 
Date registered: Jun 2009
Posts: 22
Mentioned: 0 Post(s)
Quoted: 0 Post(s)
The heat of the manifold has nothing to do with the brake system. Your Mercedes most likely needes to be flushed out several times over a course of time. A one time bleed out won't do it especially if the car has been neglected since day one. Not saying it happened to you. It happened to me.
I replaced all brake rotors, pads and the master cylinder went out after that.
It will help if I flush the brake system again in a couple of months.

I have a knack for this stuff.
GenBiltstein is offline  
Sponsored Links
Advertisement
 
Reply

  Mercedes-Benz Forum > General Mercedes-Benz Forums > Vintage Mercedes-Benz

Quick Reply
Message:
Options

Register Now



In order to be able to post messages on the Mercedes-Benz Forum forums, you must first register.
Please enter your desired user name, your email address and other required details in the form below.

User Name:
Password
Please enter a password for your user account. Note that passwords are case-sensitive.

Password:


Confirm Password:
Email Address
Please enter a valid email address for yourself.

Email Address:
OR

Log-in











  • Currently Active Users Viewing This Thread: 1 (0 members and 1 guests)
     
    Thread Tools
    Show Printable Version Show Printable Version
    Email this Page Email this Page
    Display Modes
    Linear Mode Linear Mode



    Similar Threads
    Topic Author Forum Replies Last Post
    2001 C240 Brake light failure leading to ESP/BAS Failure lxshk Audio & Telematics Forum 1 08-04-2008 10:54 PM
    1974 450SLC Brake system rebuild. Jonathan Fennell R/C107 SL/SLC Class 21 11-29-2007 03:02 PM
    1974 450SEL with 971K miles Kalifornia W116 S, SE, SEL, SD Class 1 08-31-2006 01:30 AM
    Value of 1974 450sel? kaz1961 Vintage Mercedes-Benz 2 10-22-2004 03:05 AM
    Brake system failure indication Tom Hock W163 M-Class 11 06-26-2004 10:06 AM

    Posting Rules  
    You may post new threads
    You may 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 Off
    Trackbacks are On
    Pingbacks are On
    Refbacks are On

     

    Title goes here

    close
    video goes here
    description goes here. Read Full Story
    For the best viewing experience please update your browser to Google Chrome