Strange brake problem
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Cross-Country
Joined: Oct 2004
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Strange brake problem
About three months ago I rebuilt a good portion of the brake system. I replaced the flex lines that go to the front wheels, wheel cylinders, new shoes, turned the drums, and bled with new fluid. All worked great until the other day. A few days ago we had a cold snap and its been down to about 10 degrees or less at night and not much warmer during the day.
On my way to work one morning I hit the brakes, the peddal was really soft and I could barely stop. I proceded to work, giving my self some extra room for stopping, and tested the brakes again. They worked fine and the peddal was no longer soft. The time the peddal went soft, the brake warning light came on. The next time when I had good brakes, the light went out then came back on.
Since then, the brake warning light has been on all the time. Most of the time the brakes work fine but once in a while the peddal goes soft and I can barely stop.
I know the brake light is activated by the proportioning valve going over to one side indicating a problem.
I've not pulled my wheels to see if there is a problem, but I know there are no leaks. I've lost no fluid at all.
Just curious what you all think?
Regards,
Jeremy
On my way to work one morning I hit the brakes, the peddal was really soft and I could barely stop. I proceded to work, giving my self some extra room for stopping, and tested the brakes again. They worked fine and the peddal was no longer soft. The time the peddal went soft, the brake warning light came on. The next time when I had good brakes, the light went out then came back on.
Since then, the brake warning light has been on all the time. Most of the time the brakes work fine but once in a while the peddal goes soft and I can barely stop.
I know the brake light is activated by the proportioning valve going over to one side indicating a problem.
I've not pulled my wheels to see if there is a problem, but I know there are no leaks. I've lost no fluid at all.
Just curious what you all think?
Regards,
Jeremy
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Cross-Country
Joined: Oct 2004
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I tried that but the pedal didn't seem to go down any further.
Originally Posted by buzzbait65
sounds like the master cylinder, if you hold steady, but not too hard, pressure on the brake pedal, see if it drops slowly, if it does then replace the master cylinder
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Joined: Nov 2003
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From: East Flat Rock NC
You could had some water in the fluid, do you have power brakes? If so then
the booster may be ready to fail, also check the vac line that comes from
your intake, if you have power brakes.
Wally W.
the booster may be ready to fail, also check the vac line that comes from
your intake, if you have power brakes.
Wally W.
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Cross-Country
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Well, since the cost for a new master cylinder was low, I replaced it this evening. Went for a test drive and it worked great. Braking is better than before when the brakes worked. I think you called it right buzzbait. Thanks!
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Cross-Country
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Proportioning valve reset
Evening all!
After having some brake problems this week I replaced the master cylinder. I was hoping that replaceing the master cylinder and bleeding the system my brake light would go out. Well, wouldn't you know it, its still on and the system is totally bled, no air.
I looked on my cheap shop manual and the process they recommend does not work for my rig. It says to turn the ignition to on or acc and press the brake pedal hard until the light goes out... Oh, it s a 73 F100 4x4.
Here is the question. How do I reset the proportioning valve on this rig?
jeremy
After having some brake problems this week I replaced the master cylinder. I was hoping that replaceing the master cylinder and bleeding the system my brake light would go out. Well, wouldn't you know it, its still on and the system is totally bled, no air.
I looked on my cheap shop manual and the process they recommend does not work for my rig. It says to turn the ignition to on or acc and press the brake pedal hard until the light goes out... Oh, it s a 73 F100 4x4.
Here is the question. How do I reset the proportioning valve on this rig?
jeremy
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Jerm, sometimes it works most times it doesn't.
You have to open/bleed the opposite brake circuit from the one that leaked after the repairs are done.
ie: If the front brakes failed..you open a bleeder on the back circuit.
It's a 2 person job.
You have to open/bleed the opposite brake circuit from the one that leaked after the repairs are done.
ie: If the front brakes failed..you open a bleeder on the back circuit.
It's a 2 person job.
Ford Parts Specialist
Joined: Nov 2006
Posts: 88,826
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From: Simi Valley, CA
C8AZ-2B264-A Switch, Brake Differential Warning Light.
Replace the switch...light's out.
This used to be very common problem. These switches used to fail on a regular basis, and also leak. The plastic develops minute cracks where it screws into the brass body of the Brake Differential Valve. Fluid seeps out, light comes on.
Replace the switch...light's out.
This used to be very common problem. These switches used to fail on a regular basis, and also leak. The plastic develops minute cracks where it screws into the brass body of the Brake Differential Valve. Fluid seeps out, light comes on.
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Joined: Jul 2003
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From: west central florida
Originally Posted by JermKline
Well, since the cost for a new master cylinder was low, I replaced it this evening. Went for a test drive and it worked great. Braking is better than before when the brakes worked. I think you called it right buzzbait. Thanks!
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