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I have a 1980 ford truck. I replaced my calipers, brakes, rotors, master cylinder, and porportioning valve. My brakes are still not releasing.

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I have ran acrossed several times where the rubber hoses at the calipers colaps inside and act like a flap valve . This is what i would try next.

Posted on Aug 01, 2010


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02 Ford Explorer sporttrac xlt. New rotors calipers pads and master cylinder. Bled it twice stream looks good new fluid. One day breaks stick then the next no breaks Break light on Proportional valve?

For some reason these vehicles you need to bleed brakes several times, had same problem, so air hangs up in lines somewhere it apears. When you say brakes sticks, describe it better, locked up, or dragging on rotors?

Apr 21, 2015 | 2002 Ford Explorer Sport Trac

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I need a brake line diagram for a 2001 expedition 2 wd

the brake lines start at the master cylinder they go to a porportion valve located on the frame down below the master the rear lines run down the driver side normally and uses a spitter on top of the rearend to go to the rear wheels the front basically do the same thing except the splitter is not used they also start at the master then to the porportion valve then to the calipers

May 22, 2014 | Cars & Trucks

1 Answer

1991 Chevy c1500 2wd - left brake caliper locks up after 20 miles, releases when cooled down. I removed and replaced offending caliper but problem persists

Replace the rubber brake hoses

They are collapsed inside

You never do only one caliper,
you do both

Now you need to turn the rotors & new pads
Their fried

Mar 02, 2013 | 1991 Chevrolet C1500

1 Answer

My son has replaced his wheel cylinders shoes, front pads, master cylinder and we bleed the brakes till new fluid and no air came out, and we bleed the proportion valve. But when he drives it the front...

For the brake how are the sliding pins on the calipers?They should not be corroded the caliper has to slide on it so make sure they are not corroded.Lubricate the caliper slide pin.If the caliper is clean and clear you are suffering from premature wear and high peddle effort the cause is rear hieght sensing porportioning valve.Make sure the rear height suspension proportioning valve is not affected if you modified the rear suspension you will need a kit . If you did not and the height sensing valve is intact a replacement will be required. As for the High RPM the throttle actuator is at faultcansmo_193.gifcansmo_194.gifcansmo_195.gif

Sep 10, 2011 | 1988 Ford F 250

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What makes a 1999 mercury cougar pul to one side or the other when brakes are engaged. It is NOT the callipers. They have been replaced

bad wheel bearing, worn strut mount or ball joint can do this. also a bad master cylinder, broken/leaking brake line, contaminated brake fluid, bad porportional valve, or unevenly worn rotors can all cause this.

Apr 09, 2010 | 1999 Mercury Cougar

4 Answers

Stuck calipers

You may have contaminated brake fluid. Try flushing out the brake lines, calipers, and master cylinder by bleeding the heck out of the brakes. Use a NEW can of brake fluid (see why below). This is something overlooked in vehicle maintenance. Whenever doing a brake job, flush the system. I learned the hard way, having calipers drag, not fully releasing, to change them and have it happen again. Finally figured out it was bad fluid which was ruining the calipers. Brake fluid absorbs moisture, which will wreck the system. Just leaving a bottle of fluid with a loose, or missing cap will allow moisture to enter. Brake lines will rust on the inside, and loose particles of rust floating around will cause big problems.

Mar 09, 2010 | 1998 Ford F150 Regular Cab

1 Answer

Brake porportion valve on 1982 ford F-150 moved off of center. How to adjust

If you are certain your valve is the problem, then you need to replace it, you can't adjust it. You should make sure your calipers and drums are correctly functioning. Make sure your master cylinder is functioning correctly, as well as making sure that your brake lines are not stopped up or leaking. Replacing the proportion block is one of the hardest things you'll ever have to replace on a brake system. The bolts will be rusted.

Jan 26, 2010 | 1982 Ford F 150

4 Answers

1980 Chevy Truck Brake Locked Up

There are times when the rubber brake lines start to come apart internally and act like a one way valve. they let the fluid in, but will not let it out.

Try this: The the brakes are locked up release the bleeder on the caliper. if pressure come out there, lock up again, and release the hose where it goes into the metal line. This may be hard because of rust, but you will probably have to replace the line anyway.

You may have a bad Master, but odds are it is the rubber lines. Hope this helps.

Nov 06, 2009 | 1983 Chevrolet K1500

1 Answer

Passenger side front brake caliper is not releasing.

well your brake porportion valve is not working right oh well good luck

Jun 03, 2009 | 2005 Dodge Caravan

1 Answer


Flexible brake lines are probably balooning out causing pressure not to build up, replace flexible to the calipers.

Jul 26, 2008 | 1989 Chevrolet Silverado 2500

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