Spongy Breaks
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Trailering
Joined: May 2021
Posts: 18
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Spongy Breaks
Have a 95 F-150 that had sat for 4 years in a guys barn. Got her running and now working on break system.
replaced the master, calipers, drum cylinders, and bled everything more than once.
opened up the RABS valve, bled that as well.
checked booster check valve and seems to be ok - but this is the only part I have not changed in the system.
when the truck is off, I can get pressure at the pedal and it will hold pressure for a few minutes. If I start the truck the pedal immediately drops out and will not build pressure.
All the lines are good and don’t see any obvious leaks through the system.
any ideas? Thinking I may just change the booster, but that’s another $100 down the drain if not the problem.
replaced the master, calipers, drum cylinders, and bled everything more than once.
opened up the RABS valve, bled that as well.
checked booster check valve and seems to be ok - but this is the only part I have not changed in the system.
when the truck is off, I can get pressure at the pedal and it will hold pressure for a few minutes. If I start the truck the pedal immediately drops out and will not build pressure.
All the lines are good and don’t see any obvious leaks through the system.
any ideas? Thinking I may just change the booster, but that’s another $100 down the drain if not the problem.
Thread Starter
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Trailering
Joined: May 2021
Posts: 18
Likes: 0
Cannot hear a hissing sound, not to say it’s not there. I don’t know what 3 rubber hoses you mean
I am going to replace the booster just to clear that part of it. If that’s not it….might just have a bon fire
I am going to replace the booster just to clear that part of it. If that’s not it….might just have a bon fire
Cargo Master
Joined: Mar 2010
Posts: 3,342
Likes: 294
From: Laramie, WY
There's rubber segments of brake hose. One on each side on the front axle, between the caliper and the spring buckets, and one in the rear, between the T on the axle and the frame cross member. They can degrade and swell under pressure, damping the pressure that would otherwise actuate the wheel cylinders and caliper pistons. Cheap parts, maybe a pain to replace if the fittings are rusty. But if they're junk, they're junk.
Lead Driver
Joined: Jun 2021
Posts: 5,221
Likes: 805
Have a 95 F-150 that had sat for 4 years in a guys barn. Got her running and now working on break system.
replaced the master, calipers, drum cylinders, and bled everything more than once.
opened up the RABS valve, bled that as well.
checked booster check valve and seems to be ok - but this is the only part I have not changed in the system.
when the truck is off, I can get pressure at the pedal and it will hold pressure for a few minutes. If I start the truck the pedal immediately drops out and will not build pressure.
All the lines are good and don’t see any obvious leaks through the system.
any ideas? Thinking I may just change the booster, but that’s another $100 down the drain if not the problem.
replaced the master, calipers, drum cylinders, and bled everything more than once.
opened up the RABS valve, bled that as well.
checked booster check valve and seems to be ok - but this is the only part I have not changed in the system.
when the truck is off, I can get pressure at the pedal and it will hold pressure for a few minutes. If I start the truck the pedal immediately drops out and will not build pressure.
All the lines are good and don’t see any obvious leaks through the system.
any ideas? Thinking I may just change the booster, but that’s another $100 down the drain if not the problem.
Lol, might want to step back and clarify what "only" means
Lead Driver
Joined: Jun 2021
Posts: 5,221
Likes: 805
If its original, ITS BAD. They are not something that can last 20+ years in someones garage without truly encountering wear. what color is your fluid, did you push out fluid from the end of the lines at the wheels. and did you adjust your rear brakes in addition to the hardware
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Trailering
Joined: May 2021
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All new calipers, drums, clean fluid, new bearings on front, new hardware on back, new master cylinder, drum cylinders, new booster.
No external leaks that I can see. Pedal gains pressure with truck off but will not gain pressure when running
No external leaks that I can see. Pedal gains pressure with truck off but will not gain pressure when running
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Lead Driver
Joined: Jun 2021
Posts: 5,221
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When you say no pressure when running, to be clear, you arent holding it to the floor then turning it on?
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Trailering
Joined: May 2021
Posts: 18
Likes: 0
‘95 F150 Spongy Breaks
Hello, need help with why I may have spongy breaks still
- new master cylinder
- new proportioning valve
- bled RABS valve
- new booster
- new front calipers and pads
- new rear disk hardware
- bled a dozen different times in correct order (no air bubbles)
- clean fluid through system
- no visible leaks
thinking of replacing hoses - but I don’t see any leakage and just tired of throwing money at parts. Truck builds pressure when pumping breaks and looses pressure when you stop (leak?) Also builds better pressure with truck off and as soon as I turn it over it looses all pressure that has built up.
- new master cylinder
- new proportioning valve
- bled RABS valve
- new booster
- new front calipers and pads
- new rear disk hardware
- bled a dozen different times in correct order (no air bubbles)
- clean fluid through system
- no visible leaks
thinking of replacing hoses - but I don’t see any leakage and just tired of throwing money at parts. Truck builds pressure when pumping breaks and looses pressure when you stop (leak?) Also builds better pressure with truck off and as soon as I turn it over it looses all pressure that has built up.
Cross-Country
Joined: Apr 2009
Posts: 72
Likes: 5
Did you adjust your drum brake shoes so they just touch or drag a little as you put the drum on? If the shoes are not adjusted out they will expand a lot as you push the pedal, which makes it hard or impossible to get enough pressure.
Hotshot
Joined: Jun 2015
Posts: 12,878
Likes: 2,446
- new master cylinder
thinking of replacing hoses - but I don’t see any leakage and just tired of throwing money at parts. Truck builds pressure when pumping breaks and looses pressure when you stop (leak?) Also builds better pressure with truck off and as soon as I turn it over it looses all pressure that has built up.
thinking of replacing hoses - but I don’t see any leakage and just tired of throwing money at parts. Truck builds pressure when pumping breaks and looses pressure when you stop (leak?) Also builds better pressure with truck off and as soon as I turn it over it looses all pressure that has built up.
You cannot see the inside of the rubber hoses. They deteriorate over time and can collapse internally.
Thread Starter
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Trailering
Joined: May 2021
Posts: 18
Likes: 0
Master Cylinder
I tried to bleed the new master cylinder Installed.
should I pull the master and purchase a bench bleed kit or think about the hoses first?
one thing I have noticed when bleeding the rear - it has good fluid pressure for a short second and then all fluid flow pretty much stops…I would think the system pressure would at least keep it leaking like I see on the front calipers
should I pull the master and purchase a bench bleed kit or think about the hoses first?
one thing I have noticed when bleeding the rear - it has good fluid pressure for a short second and then all fluid flow pretty much stops…I would think the system pressure would at least keep it leaking like I see on the front calipers
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