Problem when bleeding brakes

colinsco · 01-30-2010, 10:01 AM

Last week I installed new ATE calipers on the front of my '88 Carrera, and rebulit the rear calipers. Used a pressurized bleeder assistant to put 2+ quarts through the system, following the pattern in Waynes 101 projects. Still not firm so had my son help with the old two-person method. Rear calipers were both clear and firm but the new front calipers seem to continue to spew heavily aerated fluid through the clear tube and into the jar. I drove it all week and the pedal was always firm and I never worried about the braking force. This morning the boy and I again bled the system together and still the front calipers spewed what looks to be heavily aerated fluid. I can't believe there could still be air in the system after all the fluid we put through and wonder is this might be turbidity from the force of the flow and not air. Can anyone help me understand? Thanks!

911pcars · 01-30-2010, 11:55 AM

Using low air pressure as recommended? around 10-15 psi is what most folks report.

If you allow the BF to just flow from the reservoir into the caliper (w/o bleeder pressure) and out through a hose attached to the bleeder screw, you could bleed as well as confirm the same w/o wasting quarts of BF.

MHO,
Sherwood

kidrock · 01-30-2010, 12:08 PM

+1 w/ Sherwood, gravity bleeding is pretty much fail safe.

IMHO, you just need to be very patient when installing brand new calipers. When installed dry, it takes quite a bit of bleeding to get all the air out. Just keep at it, be patient and the pedal will eventually firm up.

colinsco · 01-30-2010, 12:36 PM

Thanks for the suggestions. Yes, I used 10lbs pressure. I'll follow the advice of pressurizing and letting BF flow through the new calipers and out into my capture jar. As always, appreciate the resource of this forum!

Por_sha911 · Por_sha911's Garage

Quote:

Originally Posted by colinsco

the new front calipers seem to continue to spew heavily aerated fluid through the clear tube!

If the brake pedal is firm and your brakes are strong then what's the problem?

911pcars · 01-30-2010, 01:06 PM

Quote:

Originally Posted by colinsco

Thanks for the suggestions. Yes, I used 10lbs pressure. I'll follow the advice of pressurizing and letting BF flow through the new calipers and out into my capture jar. As always, appreciate the resource of this forum!

Don't drain fluid exiting the caliper. As I suggested, attach a tight-fitting clear hose onto the bleeder valve, open the valve, then allow the brake fluid to collect in the tube. Bend the tube upward to increase the capacity of fluid on both sides of the caliper. If there's air in the caliper, it'll exit into the tube in the form of visible air bubbles. Motivate lazy bubbles stuck in the caliper by tapping the caliper with a plastic mallet. You can even work the brake pedal up and down (not too far) w/o fear of drawing air into the system.

When bubbles are no longer visible in the fluid column, close the bleeder valve, then go to the next caliper. Make sure the BF level in the reservoir is always above the MC inlet port.

Sherwood