2002 TB barake problem

[jbarsalou]

TB has 165k miles on it with pads/rotors in good condition. There are no leaks or dropping of fluid level. My brake pedal can be pushed slowly all the way to the floor with the engine running. The truck stops good and stopping distance seems normal. I've flushed out and replaced the fluid and bled the brake numerous times the old fashion way and also using a power bleeder. I tested vacuum on the booster line and valve: all good there. Pedal travel test with engine off measured in normal spec. Is the problem with the power brake booster or master cylinder? Thanks!

[maxwedge]

You can do this with just about any car, as you describe, the issue is the pedal spongy during normal stops, does it sink under normal pressure not forcing the pedal almost to the floor. If you flushed the system and air entered the abs, you cannot properly bleed the system without a scanner.

[Schurkey]

There is NO WAY a brake pedal "should" go all the way to the floor. My '03 TB does NOT, no matter how long I hold the brake pedal with engine on, or off.

There is SOMETHING wrong. Possibly the ABS system is bleeding pressure to the accumulator???

There is no way I'm aware of that the brake booster can cause a dropping pedal. Master cylinder--yes. Booster--no.

[Scrapper]

Originally Posted by jbarsalou

TB has 165k miles on it with pads/rotors in good condition. There are no leaks or dropping of fluid level. My brake pedal can be pushed slowly all the way to the floor with the engine running. The truck stops good and stopping distance seems normal. I've flushed out and replaced the fluid and bled the brake numerous times the old fashion way and also using a power bleeder. I tested vacuum on the booster line and valve: all good there. Pedal travel test with engine off measured in normal spec. Is the problem with the power brake booster or master cylinder? Thanks!

i would say master cylinder if it's staying full sometimes they will use fluid brake fluid and sometimes it will stay full look behind master cyl and see if it's wet running down firewall? i really don't think booster or pedal would be rock hard like when you push on it without car running.

good luck..

[maxwedge]

I can go out to my 2002 TB start the engine a really force the pedal close to the floor, driving and stopping the truck is perfect, same with my 2003 Lesabre. Now, I am not there to see how this feels, maybe it just goes right to the floor with very little effort, then there is a problem.

[gmtech1]

I agree with Maxwedge, I have seen several different vehicles that I could force the pedal very near the floor and the vehicle stopped fine, was a normal condition. If it goes to the floor with little effort though, I would look at the master cylinder.

[Schurkey]

Originally Posted by jbarsalou

pedal can be pushed slowly all the way to the floor

Originally Posted by maxwedge

almost to the floor.

Originally Posted by Schurkey

There is NO WAY a brake pedal "should" go all the way to the floor.

Originally Posted by maxwedge

close to the floor,

Originally Posted by gmtech1

very near the floor

If the pedal is on the carpet, THERE'S A PROBLEM. It will almost certainly be the master cylinder; although I'm thinking some ABS systems could have a defect in the accumulator or isolation valves.

If the pedal is NEAR the floor--and there are no functional issues with the braking power, no excessive wear anywhere in the brake system, and no loss of fluid--I would suggest installing DOT-APPROVED steel braid-over-Teflon liner brake hoses. I have done this on several vehicles with improvement (reduction) in pedal travel. The Teflon-liner hoses don't "balloon" under pressure, therefore less fluid is required from the master cylinder to actuate the brakes. This does NOT make the brakes more powerful, but it can make the brake pedal firmer and more easy to modulate under panic-braking conditions. Current versions of these hoses will have a plastic outer jacket that prevents grit from getting between the Teflon liner and the braid. This grit can abrade the Teflon leading to hose failure.

[maxwedge]

Originally Posted by Schurkey

If the pedal is on the carpet, THERE'S A PROBLEM. It will almost certainly be the master cylinder; although I'm thinking some ABS systems could have a defect in the accumulator or isolation valves.

If the pedal is NEAR the floor--and there are no functional issues with the braking power, no excessive wear anywhere in the brake system, and no loss of fluid--I would suggest installing DOT-APPROVED steel braid-over-Teflon liner brake hoses. I have done this on several vehicles with improvement (reduction) in pedal travel. The Teflon-liner hoses don't "balloon" under pressure, therefore less fluid is required from the master cylinder to actuate the brakes. This does NOT make the brakes more powerful, but it can make the brake pedal firmer and more easy to modulate under panic-braking conditions. Current versions of these hoses will have a plastic outer jacket that prevents grit from getting between the Teflon liner and the braid. This grit can abrade the Teflon leading to hose failure.

Good advice!

[Scrapper]

Originally Posted by jbarsalou

TB has 165k miles on it with pads/rotors in good condition. There are no leaks or dropping of fluid level. My brake pedal can be pushed slowly all the way to the floor with the engine running. The truck stops good and stopping distance seems normal. I've flushed out and replaced the fluid and bled the brake numerous times the old fashion way and also using a power bleeder. I tested vacuum on the booster line and valve: all good there. Pedal travel test with engine off measured in normal spec. Is the problem with the power brake booster or master cylinder? Thanks!

i want to add you should atleast be able to put your foot under brake pedal with your other foot holding brake pedal down.