No leaks..... stops the truck dead in place.. only way to get it to move is to reach down and grab the pedal and pull it back up by hand to get them to release..
the truck is a 2002 4x4 2500.. it's been sitting for 4 months because I've been away for work..
just had it in for a full brake replacement ( pads & rotors 4 wheel disk ) at the dealer right before I left.... ( drove it for 2 weeks before I left everything was fine )
I'm really getting frustrated at this thing..
anyhow any ideas where to start looking,, hate to take it back to the dealer yet again..

 

The fluid is still full in the master cylinder? I'm wondering if they did not get all the air bled out of the syst. when they worked on it.

 

Air in the system wouldn't keep the brakes engaged.

 

OK, so your helpful advice would be?????????

 

sounds like master cylinder or hydroboost problems. i wonder if the hydroboost is sticking at the bottom?

 

Is there a way to check the hydroboost?

 

Did they replace hydro-boost or master cylinder? To test booster follow these steps:

BOOSTER FUNCTION TEST

With the engine off depress the brake pedal several times to discharge the accumulator. Then depress the brake pedal using 40 lbs. of force and start the engine. The brake pedal should fall and then push back against your foot. This indicates the booster is operating properly.

ACCUMULATOR LEAKDOWN
1.Start the engine, apply the brakes and turn the steering wheel from lock to lock. This will ensure the accumulator is charged. Turn off the engine and let the vehicle sit for one hour. After one hour there should be at least two power assisted brake application with the engine off. If the system does not retain a charge the booster must be replaced.
2.With the engine off depress the brake pedal several times to discharge the accumulator. Grasp the accumulator and see if it wobbles or turns. If it does the accumulator has lost a gas charge and the booster must be replaced.

 

nope they just replaced pads and rotors..
but..brake pedal hits the floor on first pump, has some resistance going down but fails to rise back up.
so thinking the booster would need replaced?
however a question. if I run the steering wheel lock to lock a few time would that recharge the booster? and would it be normal for the charge in the booster to be lost from the truck just sitting?
it's been started and left running for a while a few times a month just to keep everything charged. but, hasn't been driven in that time..

 

Great info., Thanks!!!

 

Power steering fluid good, the hydroboost runs of of it......