BOTH front calipers stuck ? - follow up

[Ben Swann]

Dave,
 
If you are into diagnosis, I can send you several MC's that I removed from cars that
were having this same problem.  MC heats up due to bad location and wont' release
pressure.  It happens more when brakes are  used in stop and go traffic and using AC and
can be a real drag, literally.
 
I learned long ago not to waste my time trying to figure this one out.  For some reason,
when you remove the MC from the car that is having this problem, and replace it with a
new or rebuilt unit, the problem goes away.  Is the MC bad?  I don't know.  Will
replacing it fix the problem.  95% certainty it will.
 
You do need to bleed system and a good system flush is in order, so that may be part of
the fix and even a temp workaround.  I don't like to waste time, so Replacement seems to
be the best option at around $100 and around an hour to replace and bleed.
 
IMO don't waste too much time tring to figure it out, not worth it.
 
Ben

  _____  

From: David Michael [mailto:adavidmichael at gmail.com] 
Sent: Tuesday, December 15, 2009 1:58 PM
To: Quattro List
Cc: Ben Swann; kneale at coslink.net; Tony Hoffman; amdickinson at rogers.com; urq at pacbell.net
Subject: RE: BOTH front calipers stuck ? - follow up


Thank you to all those who have responded - the posts were all very helpful.
 
I am leaning towards the MC, even though I have not done a lot of diagnosis. But this is
what I have done:
 
1. When everything is cold, the brake calipers release just fine - I can press and
release the brake pedal, and the front wheels will spin
3. I made it home yesterday with no problem - or at least no smoke
4. This morning, the calipers started to stick just before I arrived at work (25
minutes), based on my finely calibrated  "how well does the car coast"  gauge.
 
I need to crack the bleed screw at a caliper when they stick, but its yucky on the
ground now, and its dark when I get home. Is the bleed screw at the MC the same pressure
as the calipers - that would be easy to check ;-)?
 
Thank you all again!
 
Dave
90 200 QA 230k
98 M3/4 101k
02 MCS 40k