[W126 Coupe] Brakes and air

[Chet Hwilka]

Ronny, 

 

As Jonathan probably told you, the reason you don't want to use the old
'pumping the pedal' method is because you may end up damaging the seals in
the MC.   The old PTP method involves having 2 people working on bleeding
the system, one person pumps the pedal and one person opening a valve on
each caliper, which squirts out brake fluid and along with the any air at
that caliper.  The pumper pumps the pedal several times and when directed by
the bleeder, holds the pedal as the valve is open.   The pedal will go to
the floor and the pumper MUST hold the pedal to the floor until the bleeder
closes the valve, that way air won't get sucked back into the system.  

The problem with that method is, when the pedal goes to the floor, the
piston inside the MC travels to an area not normally accessed and if that
area of the cylinder walls has any pitting or rust, it will damage the seals
on that piston, which now will cause leakage and a spongy pedal.   The
pitting and rust within the hydraulic system results from not regularly
replacing the brake fluid.  Moisture gets trapped in the system over
time/use and that's why you must replace the B/F year or 2.

 

Chet

 

 

  _____  

From: mbcoupes-bounces at mbcoupes.com [mailto:mbcoupes-bounces at mbcoupes.com]
On Behalf Of Ronny 560sec
Sent: Thursday, December 16, 2010 6:11 PM
To: Mercedes Coupes Mailing Lists
Subject: Re: [W126 Coupe] Brakes and air

 

Mark,

I have not replaced the MC, but this morning I had a conversation with
Jonathan and he told me that my garage guy should use a pressure bleeder and
not do the old way of pumping the pedal.
I just came back from the garage and they already were thinking of replacing
the MC, but after my talk to them they ordered the Motiv pressure bleeder.

Thank Jonathan.

 

Ronny 

 

 

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