brake pedal goes to the floor

[Flpstyl]

92 Suburban, found leak in the rear brake cylinder, so I replaced both. Bled system. With the engine off, pedal would be firm but when i would start the engine, pedal would go to the floor. I thought it was the master, so replaced it, and it still does the same thing. Engine off, pedal would firm up after a couple of pumps, but with the engine on, it would go to the floor. I would also get this mechanical type growl coming from the hood when I would step on the pedal hard. Could it be my ABS malfunctioning? Please help, I use my truck for work at a teen center and I need it be safe and reliable.

[jfmctlaw]

Teens? I thought we were trying to eliminate all teenagers! :-)

You say the pedal goes to the floor when running. If that's happening there must be 1)fluid leaking somewhere, 2) a lot of air in some line/cylinder, or you still have a worthless master. If you keep pumping what happens to your reservoir level, does it go down (sign of leak) or stay the same (sign of air or bad master). The difference between engine on and off is vacuum being supplied. Several brakes pumps after the engine is off depletes the residual vacuum and you are back to a stiff pedal. The engine off situation is not indicative of anything except the huge mechanical advantage the vacuum provides. Make sure all your vacuum lines are connected and there are no leaks (hissing noises).

[jmc9999]

I've got the exact same problem with my '02' suburban. Have had it into multiple dealers multiple times. They also replaced the master cylinder but the brake pedal still goes to the floor. They continue to tell me that it is normal and there is no problem.

I'd be interested if you have had any success in fixing the issue or finding the problem.

In addition I have continuous issues with the parking brake not holding. They fixed it once under a service bulliten but it still doesn't hold.

[chuck's]

Hey jmc999.I recently had the pleasure of working on a 2004 pick-up with rear caliper brakes.I do believe that your 2002 suburban has the same.Anyway, I found out that the park brake shoe has to be adjusted to fit to the caliper.If it isn't done ,the park brake lining will not touch the inside of the caliper.Hopefully this will help you.

chuck's