1998 Chevy Silverado 1500 Brake Pedal Goes to Floor

[AlexHoopes]

Hey all, I just replaced my vacuum brake booster and the pedal goes to the floor once the engine is started, holds pressure while it is off, master cylinder has already been replaced. Am I supposed to bleed after I take booster off? Also, it will not shift out of park when truck is running but will shift when truck is not running. Brake light comes on, the clip was replaced. Anyone got any insight as to what it may be?

 

[Nad_Yvalhosert]

There's no need to bleed the brakes if you didn't open the hydraulic system.

When did you... why did you...
1: replace the master?
2: replace the booster?

Shift interlock is electric. Did you mess up the adjustment on the brake switch on the pedal?

What "brake light" comes on? Dash or tail & 3rd?

What rod did you use with the new booster?

Is the new booster the same as the old one? Can you remove and compare the old & new rods?

 

[AlexHoopes]

There's no need to bleed the brakes if you didn't open the hydraulic system.

When did you... why did you...
1: replace the master?
2: replace the booster?

Shift interlock is electric. Did you mess up the adjustment on the brake switch on the pedal?

What "brake light" comes on? Dash or tail & 3rd?

What rod did you use with the new booster?

Is the new booster the same as the old one? Can you remove and compare the old & new rods?

Replaced master because there was no pressure in the brakes, 5 days ago, removed booster because brakes were extremely hard and stuff. I did not touch the brake shift, brake tail lights come on when pedal is pressed, used the rod from the old booster on the new master, new booster came with new rod now using that. Also, just disconnected vacuum hose to booster while truck was running and the brake doesn’t go to the floor when that happens, could it be something as simple as a hose?

 

[Nad_Yvalhosert]

So... soft/low brake pedal led to changing the master. New master bled and installed. Good pedal height?

GM trucks, running in park, always did have an... unimpressive, almost spongy pedal feel, until you're driving.


Hard pedal means no vacuum assist. New booster and pedal goes to floor? Either the rod is the wrong length, or the booster is defective.
Try using the known correct rod in the new booster. If the pedal is good height, the master is good. If the assist is bad, that's not the fault of rod or master

Disconnecting the vacuum hose, engine running should leave you with a hard pedal, at good height, meaning no hydraulic problems. Reconnect the hose. If it goes to floor then suspect defective booster.

 

[Supercharged111]

Do you have the brackets behind or in front of the master? Can you post a pic? My guess is your master was not properly bled when replaced.

 

[Nad_Yvalhosert]

If you, key on, lightly tap on and off the brake pedal, you'll hear the shift interlock solenoid locking and unlocking the shifter. If you dont, the switch on the pedal is out of adjustment.

 

[AlexHoopes]

If you, key on, lightly tap on and off the brake pedal, you'll hear the shift interlock solenoid locking and unlocking the shifter. If you dont, the switch on the pedal is out of adjustment.

I do not hear this at all, is it something to do with me taking off the brake light switch? The brake lights still work though? The clip isn’t in all the way I couldn’t get it in all the way.. could that be it? The electrical connector was never touched

 

[AlexHoopes]

Do you have the brackets behind or in front of the master? Can you post a pic? My guess is your master was not properly bled when replaced.

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[Erik the Awful]

It sounds like your master cylinder wasn't fully bled and the clip on your brake switch needs to be properly installed. Bleed the crap out of your brakes.

A failed brake booster will not cause the pedal to go to the floor. It uses engine vacuum to help pull the brake pedal down, and if the diaphragm fails it doesn't help.

 

[DerekTheGreat]

Wow.. That engine bay looks like the pit of a public port-a-john after a 4th of July party.