therock

iTrader: (2)

My brakes have been less than optimal lately with a softer pedal feel so I had a dealership purge and bleed the system including the ABS.
Still with new pads my pedal doesn't feel right.
I can push and hold the pedal with the engine running and it will slowly or eventually go to the floor.
With the engine off it will hold rock solid. Vacuum booster problem?

This is a 2005, the year they upgraded to larger rotors, better calipers & master cylinder, rear drums bragging the booster was smaller because of these upgrades.
It was one stopping *****! Now not so good.

What do you think, give me some methods of testing if the above doesn't confirm its the booster.

Thanks

RB04Av

NOT the booster. (or hydraboost, if you had that)

Master cylinder.

Only because you can't push on it hard enough to make it leak enough to notice in the time you are pushing on it... the booster multiplies whatever force you stomp on the pedal, by a factor of about 3.

therock

iTrader: (2)

Thanks,

I swapped the master cylinder out and it will go almost to the floor if I press and hold long enough with engine running, but not all the way.
This 2005 rear drummed truck used to stop better than this. I loved it. Now its so-so. Must be the pads and shoes, OE long gone.

I had ATE 200 Amber in it and with the new MS I bled it out with Valvoline Syn, DOT 3-4 and the amber came out really cloudy and took two quarts to clear it out and its still not totally without color.
After the last bleeding I took a sample into a clear shot glass and held a flash light under it and could see super fine tiny bubbles, or it looked like bubbles. Cavitation going by the bleeder?
I have SS braided lines on the truck.