Brake Problem (proportioning valve) please help
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Brake Problem (proportioning valve) please help
I have a 76 4x4 with a 360. My problem is this.
THe brake light came on.
First I topped it off with fluid.
No such luck.
I checked out the proportioning valve and the post that is held out during bleeding was all the way out already.
I pushed it back in, and pumped the brakes a few times, the light went out. test drive
before I got out of my driveway the valve popped again, push it in, same thing over and over.
I can't seem to find one yet, napa is closed, as well as the stealership.
Am I wrong to assume my p-valve is bad?
THe brake light came on.
First I topped it off with fluid.
No such luck.
I checked out the proportioning valve and the post that is held out during bleeding was all the way out already.
I pushed it back in, and pumped the brakes a few times, the light went out. test drive
before I got out of my driveway the valve popped again, push it in, same thing over and over.
I can't seem to find one yet, napa is closed, as well as the stealership.
Am I wrong to assume my p-valve is bad?
Postmaster
Joined: Apr 2002
Posts: 3,613
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From: Coal country
That pop-out means that the pressures in the front brake lines and rear brakes lines is not the same.
They are supposed to be the same.
If one goes out, then the pressure differential makes the valve pop out, telling you that problems exist.
There is a leak somewhere, or the master cylinder is bad, and only one system is delivering pressure - or the other one is delivering partial pressure.
Leaks can be caused by wheel cylinders or calipers leaking or popping out as well as leaking lines somewhere. Leaking rubber lines can do the same. There are lots of possibilities.
You need to check your brake system, not replace the proportioning valve. Start with the basics and the obvious, and start with the front brakes, as they provide the most braking power for the truck.
Good luck, let us know what you find and what happens, and if you need any help.
They are supposed to be the same.
If one goes out, then the pressure differential makes the valve pop out, telling you that problems exist.
There is a leak somewhere, or the master cylinder is bad, and only one system is delivering pressure - or the other one is delivering partial pressure.
Leaks can be caused by wheel cylinders or calipers leaking or popping out as well as leaking lines somewhere. Leaking rubber lines can do the same. There are lots of possibilities.
You need to check your brake system, not replace the proportioning valve. Start with the basics and the obvious, and start with the front brakes, as they provide the most braking power for the truck.
Good luck, let us know what you find and what happens, and if you need any help.
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Joined: Jan 2008
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The fact that you got the light to go out before the test drive tells me it is a minor problem.
As BP says you need to inspect for a hydraulic leak in one of the circuits.
If after a Thorough Inspection there aren't any visible brake fluid leaks ,you can purchase a new adjustable PPV at a parts house.
You can try sending the valve back into center by pressing real hard on the pedal.
As BP says you need to inspect for a hydraulic leak in one of the circuits.
If after a Thorough Inspection there aren't any visible brake fluid leaks ,you can purchase a new adjustable PPV at a parts house.
You can try sending the valve back into center by pressing real hard on the pedal.
Senior User
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Originally Posted by banjopicker66
............the master cylinder (insert....could be) is bad, and only one system is delivering pressure - or the other one (could be) is delivering partial pressure.
............or none at all
In other words an internal master cyl leak, or bypass, from one system to the other. <O
If you have no visible leaks, that is where I would look for the prob.<O
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The Fronts are the only ones working, they lock up if I step on it hard enough, So I'm thinking the problem is in the rear then
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The way the Ford system works is:
the rears are supposed to come on first.
Then the fronts come on and become the main braking.
I think you need to check the rears for the proper adjustment of shoes to drums.
Plus a wheel cylinder leaking slightly.
Unfortunately the drums have to come off for a proper inspection.
the rears are supposed to come on first.
Then the fronts come on and become the main braking.
I think you need to check the rears for the proper adjustment of shoes to drums.
Plus a wheel cylinder leaking slightly.
Unfortunately the drums have to come off for a proper inspection.
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Thats no problem, I don't think its a misadjustment problem, they have worked fine for the last 4k miles, it sat for maybe a month and change, then got in and the brake light was on. I'll probably plumb all new line from the p-valve back, new wheel cylinders, new shoes, and new hardware kit for both wheels.
I work at advance, so the parts won't cost to much and I can do all the work myself, the bad thing is I was sposed to go to STL MO to pick up a jetta I just bought and trailer it home, 10mpg there and back 200 miles yay.
Thanks again for all the input guys, this forum truely is helpful
I work at advance, so the parts won't cost to much and I can do all the work myself, the bad thing is I was sposed to go to STL MO to pick up a jetta I just bought and trailer it home, 10mpg there and back 200 miles yay.
Thanks again for all the input guys, this forum truely is helpful
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Great news, replaced the line from the P valve to the axle and rebuilt both drums, new hardware and cylinders, and it works good again, thanks for the advice guys you saved me from buying a bad p-valve