ajg617

Front brakes on the C5 for the 5th time this weekend (they don't last long for me for some reason). I can never get all the air out (manually with someone at the brake pedal). Not sure if it because car is up on jack stands in the front and the angle is causing a pocket that just won't come out. Went through 2 litres of fluid last time and my indy bled them when I brought it in for service because he couldn't stand the mushy pedal. Been manually bleeding brakes for over 40 years and no joy with this one.

Suggestions welcome.

SloopJohnB@mac.com

I generally power bleed with about 29psi air pressure.
There have been a few bad master cylinders when all else has been ruled out.

sounddude

Indeed, wouldn't be the first bad MC I pulled out of the box.

SloopJohnB@mac.com

And that's the real sphincter-clincher…bad new parts, counterfeit new parts, poorly reman new parts. I once went through three rebuilt Girling master cylinders for my old Saab before I (epiphany!) realized the seals weren't happy with Castrol LMA DOT(4?) brake fluid. I've since gone to ATE racing blue or amber on a two year bleed or during pad replacement cycle.

The power bleeder makes it about a one hour job…most of the time is taken up pulling off the wheels (and cleaning them since I do it during snow tire changeover) and replacing them.

Prospeeder

I have gone through the same thing a few times. The booster can get damaged somehow and the pushrod will break loose inside. If you remove the master and you can remove the booster pushrod or you find the little star looking washer laying in the booster its a bad booster. If the pushrod is not attached it seems to not give full travel and doesnt bleed all the air out.