I've watched and learned plenty from your videos - thank you! Today I could use your expertise because the dealership cannot seem to figure it out. They've had the car since Monday (today is saturday). It is an 07 impala, 3.5, flex, and the VIN is 2G1WB58K079104049. Brakes and rotors were changed by myself, then bled, the result was NO BRAKES. Rebled the brakes after taking it out and activating the ABS in case air had gotten in. Still no brakes, so i changed the master cylinder (well primed) and bled profusely. No brakes again. Then I replaced the vacuum hose and valve along with the core of the brake booster. No change. Brought it to the dealership where they replaced the entire booster. They said that wasn't it and they continue to scratch their heads. They also say there are no codes shown. Any ideas?
You can't bleed the brakes without hooking up the proper scan tool to set the ABS solenoids in the correct position to bleed the system.
I don't think a 07 will need a scan tool to bleed the brakes? I may be wrong though.
He is referring to bleeding the ABS system.
UPDATE:
07 Impala (VIN: 2G1WB58K079104049).
After 8.5 weeks at the Dealership they are throwing in the towel on why the brake pedal goes to the floor. BTW, we went through 3 different field service engineers at the dealership, a shop manager, and a couple of service mechanics too.
This all started when my son came home from school after his spring semester and we changed the pads and rotors. We used OEM parts except for rear rotors due to availability. Bled brakes (two man) several times (RR, LR, RF, LF) but brakes were intermittent - good one minute but pedal to the floor the next. It acted as if it either still had air in the system or there was a loss of pressure or fluid leak but absolutely no leaks ever appeared. We then changed the master cylinder (aftermarket) after sufficiently priming it prior to installation. When the same problem persisted we brought it to the Dealership.
The Dealership diagnosed the problem as a faulty brake booster (aftermarket) and changed it. No change in the brakes. No codes with the scan tool from the Dealership. They repeatedly bled the brakes with the scan tool to activate the ABS to remove air and air would come out each time and brakes would work fine. But the next morning the pedal would go back to the floor and there would be air in the system.
It is puzzling how air can enter (whether passively or actively) the system without fluid leaking out. To me, this defies logic and I do not believe air can enter the system passively so it would seem that air is being actively introduced somewhere. Could this occur between the brake booster and the master cylinder. Is it possible that the booster can push air into the master cylinder and somehow completely sealing (like a check vale) upon recoil and not allow fluid to leak out when brakes are disengaged?
IF YOU CAN SOLVE THIS RIDDLE YOU SHOULD PROMOTE YOURSELF FROM MASTER MECHANIC TO JEDI.
Are the calipers pushing the piston at all? Replaced a banjobolt with a regular screw?
