Inconsistent Brake Pedal Throw
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5th Wheeling
Joined: Nov 2023
Posts: 49
Likes: 2
Inconsistent Brake Pedal Throw
I have a 2005 Ford Excursion V10. The brake pedal throw is inconsistent and ocasionally goes very low. It is not a hydro boost. It has brake vacuum canister.
I changed the rear rotors, pads, rear lines and center rear hose as well as the rear caliper hoses.
I have bled the system (RR,LR,RF,LF). Multiples times using the brake motive bleeder, also tried gravity bleeding, also tried having some depress the pedal till I get clear fluid with no bubbles.
I have changed the master cylinder multiple times the last being a Motorcraft. I have bled the Master cylinder using a generic kit. I do notice tiny bubbles in the rear line when the master cylinder is bled. The front is fine.
Also the brake vacuum booster was changed as well.
Question:
1.Can the ABS be causing this issue? I have a scanner and I was able to activate the abs with my foot on the brake pedal and it pulses till it reaches the floor. I think it is the brake bleeding procedure for the abs using the scanner.
2. Is there master cylinder bleed kit that is recommended for Ford since the fitting ls are generic etc?
Also, has anyone battled a spongy pedal that seems not to go away.
Thanks in advance for any advice!
I changed the rear rotors, pads, rear lines and center rear hose as well as the rear caliper hoses.
I have bled the system (RR,LR,RF,LF). Multiples times using the brake motive bleeder, also tried gravity bleeding, also tried having some depress the pedal till I get clear fluid with no bubbles.
I have changed the master cylinder multiple times the last being a Motorcraft. I have bled the Master cylinder using a generic kit. I do notice tiny bubbles in the rear line when the master cylinder is bled. The front is fine.
Also the brake vacuum booster was changed as well.
Question:
1.Can the ABS be causing this issue? I have a scanner and I was able to activate the abs with my foot on the brake pedal and it pulses till it reaches the floor. I think it is the brake bleeding procedure for the abs using the scanner.
2. Is there master cylinder bleed kit that is recommended for Ford since the fitting ls are generic etc?
Also, has anyone battled a spongy pedal that seems not to go away.
Thanks in advance for any advice!
4th Gear
Joined: Feb 2025
Posts: 4
Likes: 3
That is an odd one! Hard to picture where in the system such a thing could happen. I've been dealing with some brake issues, and when I blew a piston out of the left rear caliper yesterday it turns out that a sticking REAR caliper was causing problems w/ FRONT chattering / squealing when coming to a complete stop! Had the fronts off, rechecking & silglyde everywhere. But with a new REAR caliper the FRONTS are behaving normally! Now I think I need a PS pump as it is moaning & has an inconsistent / weak feel at times. I am assuming it's the pump vs hydroboost, that is a new system for me (the hydroboost).
Fluid levels aren't dropping for you, so no major leak. Tiny air bubbles = still some air in system. Hard to picture that causing such dramatic variation. I would suggest doing the 'on-car' master cylinder bleed: simply connect a hose to left front bleeder & run it back into the master cylinder. Guy in this
had a good suggestion of putting a coffee filter over the end of the tube to catch debris. Once the tube is full (keep a close eye on fluid level) just keep recycling the fluid. Also: only press 1/2 - 2/3 of the way down to protect seals in master.
Fluid levels aren't dropping for you, so no major leak. Tiny air bubbles = still some air in system. Hard to picture that causing such dramatic variation. I would suggest doing the 'on-car' master cylinder bleed: simply connect a hose to left front bleeder & run it back into the master cylinder. Guy in this
Thread Starter
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5th Wheeling
Joined: Nov 2023
Posts: 49
Likes: 2
That is an odd one! Hard to picture where in the system such a thing could happen. I've been dealing with some brake issues, and when I blew a piston out of the left rear caliper yesterday it turns out that a sticking REAR caliper was causing problems w/ FRONT chattering / squealing when coming to a complete stop! Had the fronts off, rechecking & silglyde everywhere. But with a new REAR caliper the FRONTS are behaving normally! Now I think I need a PS pump as it is moaning & has an inconsistent / weak feel at times. I am assuming it's the pump vs hydroboost, that is a new system for me (the hydroboost).
Fluid levels aren't dropping for you, so no major leak. Tiny air bubbles = still some air in system. Hard to picture that causing such dramatic variation. I would suggest doing the 'on-car' master cylinder bleed: simply connect a hose to left front bleeder & run it back into the master cylinder. Guy in this video had a good suggestion of putting a coffee filter over the end of the tube to catch debris. Once the tube is full (keep a close eye on fluid level) just keep recycling the fluid. Also: only press 1/2 - 2/3 of the way down to protect seals in master.
Fluid levels aren't dropping for you, so no major leak. Tiny air bubbles = still some air in system. Hard to picture that causing such dramatic variation. I would suggest doing the 'on-car' master cylinder bleed: simply connect a hose to left front bleeder & run it back into the master cylinder. Guy in this video had a good suggestion of putting a coffee filter over the end of the tube to catch debris. Once the tube is full (keep a close eye on fluid level) just keep recycling the fluid. Also: only press 1/2 - 2/3 of the way down to protect seals in master.
Thanks. I may try bleeding rhe master cylinder again. And take your advice on 1/2-2/3 press of the brake.
I have a generic master cylinder brake bleed kit. On one the ports, I can’t get a clean fit or so it seems. This is the line with the tiny bubbles.
Is there a kit that is specifically for Ford?
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5th Wheeling
Joined: Nov 2023
Posts: 49
Likes: 2
SOLVED
Thanks for all the tips.
Basically the front rotors were slotted and rusted? Like they were not being used. Also, the brake hoses to the caliper looked quite old.
I changed:
the front brake calipers, rotors, pads and hoses.
In the process, the right hub bearing was loose.
changed both front jun bearings with Timkin bearings.
truck brakes like brand new!
Basically the front rotors were slotted and rusted? Like they were not being used. Also, the brake hoses to the caliper looked quite old.
I changed:
the front brake calipers, rotors, pads and hoses.
In the process, the right hub bearing was loose.
changed both front jun bearings with Timkin bearings.
truck brakes like brand new!
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