2002 Mercedes Benz 500sl Brakes

Tiny
JOSEPH ANNOH
  • MEMBER
  • 2002 MERCEDES BENZ 500SL
  • 5.0L
  • V8
  • RWD
  • AUTOMATIC
  • 264,000 MILES
The brake pedal goes flat on the floor every morning when the weather temperature is between 12c and 13c. But it works perfect when the weather warms up. What's the problem?
Tuesday, July 28th, 2015 AT 5:57 PM

11 Replies

Tiny
MHPAUTOS
  • MECHANIC
  • 31,937 POSTS
There is nothing that would cause this that is temp related, if the pedal sinks to the floor you may have a by passing master cylinder, this can happen with light brake pressure with heavy pressure the seals in the master cyl will seal against the bore with more efficiency, if you had air in the system, the pedal would not recover, I would be checking the master first.
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Wednesday, July 29th, 2015 AT 3:27 AM
Tiny
JOSEPH ANNOH
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  • 6 POSTS
But I just changed the master cylinder
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Wednesday, July 29th, 2015 AT 12:48 PM
Tiny
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Did you bleed it on the bench before fitting.
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Thursday, July 30th, 2015 AT 3:36 AM
Tiny
JOSEPH ANNOH
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  • 6 POSTS
I don't know if my mechanic did. Was he supposed to do that before fitting the master cylinder?
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Thursday, July 30th, 2015 AT 8:36 AM
Tiny
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You should always bench bleed a master cyl before fitting, I would be looking at air still trapped in the system.
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Thursday, July 30th, 2015 AT 2:45 PM
Tiny
JOSEPH ANNOH
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  • 6 POSTS
Is it possible to take out the master cylinder, bleed it on the bench and fit it back. If so, how much will be your labor to get it done right?
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Thursday, July 30th, 2015 AT 7:21 PM
Tiny
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Don't take it off now it is fitted, just bleed it in the car at the pipe unions at the master cyl.
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Saturday, August 1st, 2015 AT 1:14 AM
Tiny
JOSEPH ANNOH
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Thank you so much
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Sunday, August 2nd, 2015 AT 6:45 AM
Tiny
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OK, hope all works well.
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Sunday, August 2nd, 2015 AT 2:34 PM
Tiny
JOSEPH ANNOH
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  • 6 POSTS
Where are you guys located?
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Sunday, August 9th, 2015 AT 5:35 PM
Tiny
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I am in Australia, all other techs are based in the US
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Tuesday, August 11th, 2015 AT 2:40 AM

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