This has hydro boost
I changed the master cylinder tonight... I have better braking... but pedal travels almost completely to floor before brakes begin to bite..... I adjusted the drums with no change... even with truck off I can not pump the pedal hard.. do you have any ideas? Could it be the hydro booster? I'm at a loss and need better brakes as I tow more days than not.
Pedal Height is controlled by the rear brake adjustment and it is also a possibility you have air in the system or mastercylender. You may also have a bad wheel cylender either leaking or frozen. also check for an equalizing valve if it has a tow package. These are usually attachedto the rear axle simular to GM's Load Leveler Valve Assy. for air ride systems.
It has a tow package...I can find no type of valve that you mention. I took drums apart last nite and checked for correct function... everything was working proprly... I even vacuum bled the system but still no pedal with that new master cylinder... I have better stopping ability but no pedal height...
I read online to check the hydro booster shut the truck off and pump it several times to discharge it then while holding to the floor start truck and see if it drops then kicks back up... which it did.. so ATM I'm at a loss of what could be wrong....but I need better brakes asap don't get me wrong I can stop fine... but the low pedal is not my cup of tea
the hydro boost is bad, but it cna be rebuilt, quit being a mechanic back in 2000, but pretty sure that's what the old oldsmobile diesels did with a bad booster, use to rebiuld them, but that was a long time ago