Very Spongy Brakes, '03 GMC Sierra, New Parts Too.

[Lubener]

Originally Posted By: ToadU
Check the hydra boost unit located behind the master cylinder. GMs infamous hydro boost could be the cause. Cheapest place is roackauto for a new one.


After shutting off the engine, wait five minutes and try pumpng the brakes, you should get atleast a few power assisted pumps. If not check the booster's vacuume check valve and the booster itself for leaks.

Also, if you pressed the pedal down to the floor while bleeding, the master cylinder could be internally bypassing fluid and will need replacement.

 

[Turk]

Here's an update.....

Went out this morning and did HARD braking from 65MPH to 5MPH (14) times.

Initially, I could put the pedal to the floor with moderate stopping power and no lock-ups whatsoever.

After those 14 hard near-stops, I had stuff flying forward off the back seat and hitting the back of my seat. Didn't happen before!! The tires also chirped. MUCH better stopping now.

But, man, are those rims hot; didn't dare touch anything else, lol. Brakes sure were stinky!

Drove it around to cool them off.

I think I should well-enough alone now, right??