1997 GMC Sierra Brake Issues. Need Some Advice!!!

Ton'dZon44s

New Member
Joined
Feb 28, 2010
Location
Rocky mount
l have a 1997 GMC Sierra 1500 4x4 with the 5.7 Vortec. l had originally built this truck with a s.a.s. kit. l recently decided to set it back down and put it back onto an ifs frame. l swapped everything back. l bought new master cylinder, booster, pads, calipers, wheel cylinders, rubber brake lines, just to make sure all the braking system was good. l'vehad bad luck with brakes on this truck before. truck is back complete now, l've bled the brakes several times. l bench bled the master cylinder, done each wheel individually, even back fed them. Problem is, pedal is perfect when truck is off. Crank the truck and the pedal goes straight to the floor and will not pump up. l've done everything l know to do. ls there anything else to try or that needs replacing? Any advice would be great! Thanks.
 
Make sure your bleeder screws on your cailpers are up, and not pointing down. Also try to bleed the brakes @ the master cylinder, then @ the wheels. Bleeding procedure start @ the RR,LR,RF,LF
 
bannerp said:
Make sure your bleeder screws on your cailpers are up, and not pointing down. Also try to bleed the brakes @ the master cylinder, then @ the wheels. Bleeding procedure start @ the RR,LR,RF,LF
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Have done those procedures. Not new to the brake issues on a '97 GMC. True it would be easy. Just baffling me right now.
 
Does the truck still have ABS ?? if so you might have to autobleed the pump. I am guessing you checked your wheel cylinders and made sure they are not leaking?? Last but not least maybe a bad master cylinder?? Was it a new or a reman??
 
bannerp said:
Does the truck still have ABS ?? if so you might have to autobleed the pump. I am guessing you checked your wheel cylinders and made sure they are not leaking?? Last but not least maybe a bad master cylinder?? Was it a new or a reman??
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Yes it has abs up front. Yes wheel cylinders are good. l put a reman'd master cylinder to start with and it was bad, so l ditched it and bought a brand new one from GM. What do you mean by autobleed the pump?
 
GM ABS systems require you to autobleed the pump anytime a brake line,hose,etc etc is broken loose. the pump gets air hung in the valves. Any local shop with a decent scan tool should be able to do it for you, or your dealership. Not saying that this is your problem but it couldnt hurt to try.
 
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