2008 Uplander
102,000 miles
Brakes were working ok but getting grinding noise in rear. Replaced rear pads and rotors. Replaced front pads as they were very close to being used up.
Cracked open bleeder screws as instructed when collapsing calipers as instructed for ABS vehicles.
First tried gravity bleeding but had spongy pedal. Purchased vacuum bleeder and bleed all 4 again per instructions with bleeder. Still have spongy pedal.
Odd thing is with engine off pedal feels solid and can push as hard as possible and it hardly moves and feels solid. Start engine and pedal is mushy and will go almost to floor.

 

when the car running your getting vacuum boost assist; hence the mushy brakes only when the engines running.

get a helper and manually bleed the system.

When vacuum bleeding, make sure the cap is removed from the brake reservoir or no fluid will move through the system.


yes, cracking the bleeder screws will ensure nothing gets pushed back to the abs pump but in the real world of automotive repair, it is not done. Bleeders screws seize and break. I haven't heard of problems from not cracking bleeders in 20 years. If the future,don't open the system, you won't have a problem.

 

Had the cap off the master cylinder when vacuum bleeding. pulled 3 oz. of clear fluid with no bubbles through each bleader.
Still have very mushy pedal!
Could I have gotten air into master cylinder and need to take off and bench bleed? I don't think master cylinder ever got low enough that it should have gotten air in system.

 

I have one of the best vacuum bleeders on the market. I still do a 2 person manual bleed after vacuum bleeding as I sometimes get a mushy/deep pedal after vacuum bleeding alone.