Bleeding Brakes

85911 · 85911's Garage

I rebuilt all 4 calipers and am using a Motive pressure bleeder to bleed the hydraulic system. I put a block of wood under the brake pedal to limit travel. The vent tube is pinched. The pads are seated on the rotors.

I am not getting the air out.

I've used the air pressure method, the 2 person method, and the fluid pressure method. I've gone through over 3 qts. of brake fluid. On the first pedal pump, the pedal goes to the block of wood, but stiffens up a bit when I pump about 10 times. If I let it sit for a couple minutes, I get the same result.

At the bleed screw, I am getting a solid stream of clean fluid.

I'm down to torn o-rings in the master cylinder. Perhaps my block of wood was not big enough, but I'm not confident in this theory as I have successfully bled the brakes on this car several times in the past.

Any ideas?

Thanks.

thor66 · 04-04-2021, 12:58 PM

before tearing things open, try tapping the calipers to get rid of air bubbles

85911 · 85911's Garage

Tapped on several points of the calipers several times before and after bleeding- no change.

I believe I read in a post some time ago a suggestion to bleed the system at the master cylinder. Would that be behind (towards the rear) of the booster and on the right side (passenger side) of the MC (at the brake line connection point)? However, if that's the point they were referring to, I can't imagine air bubbles getting trapped there as it is a narrow spot that feeds fluid into the brake line. If there are bubbles there, I just pumped about 4 qts. of brake fluid by them and they didn't budge.