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Caliper problems

2000 Mercury Sable Wagon. 3.0L engine, automatic transmission, 110,000 miles. Car has received scheduled maintenance. I had to replace the left rear brake caliper in Sept of 2007 and again in October of 2008. The caliper has froze up on me and needed to be replaced again. When I changed the pads on the right side, they seemed to have received normal wear. After driving 25 miles to work after replacing the caliper, it smells like it is still hanging up. The right side is fine. Does anyone have any suggestions as to why the left rear keeps freezing up?

It may be that you never needed to replace the caliper to begin with. It may be that you needed to replace a brake line.

Are those brake lines the flexible rubber kind? If so, the interior of those can break down with chunks of it acting like a check valve - allowing brake fluid through on its way to the caliper but then not allowing it to flow back to take the pressure back off. The other thing to check is the parking brake mechanism.

That’s my first guess, anyway.

The caliper was definetly frozen. I could not get the piston to retract even with the hose off and the bleed port open. Flexible rubber brake line looked to be in good condition. Parking brake mechanism is functioning/releases as designed. Thanks for the response, any other ideas?

Here are a couple more - when is the last time you flushed the brake fluid? Brake fluid is hydrophilic - it absorbs moisture. If yours hasn’t been flushed the moisture maybe accelerating corrosion in the caliper. This would likely be worse if you used a relatively low end replacement the first time. I would flush out the brake lines, replace the caliper with a mid-level choice (rather than lowest price) and see what happens. But I’m also not a brake expert - its just all I can think of that would make sense.

Thanks, I appreciate the suggestions. The brake fluid has been flushed. When I bleed the brake lines, the fluid comes out nice and clean… The caliper has been replaced with rebuilt “Ford” replacement calipers.

Check the slide pins and make sure that they are functioning correctly and are well lubed. Otherwise, it may the the brand of remade brake caliper that you are buying. I’d try a different brand for the third one.

Sorry, forgot to add that I checked/cleaned/relubricated the slide pins and everything was ok. What brand would be better than an original “Ford” caliper?

There’s nothing wrong with Ford calipers and continuing to replace the same part means a misdiagnosis.
Park brake cable hanging or whatever, but it’s not bad calipers.

Thanks ok4450, I know that it is definetly not the parking brake cable. I am leaning towards the break line. Not too expensive to replace, so I guess I will start there. I would still appreciate any other suggestions…

At 9-10yrs old replacing the brake lines is certainly reasonable even as preventative maintenance - i.e. even if it isn’t a cause of this problem. But you did state above that the caliper pistons were definitely frozen, yes? Even if the brake line has a problem I can’t see that freezing up the caliper.

Yes, the left rear caliper was frozen in the fully extended position. I could barely turn the piston even with the caliper in a bench vise. The brake pads were completely gone… The right side was fine with about 75% of pad left and I was able to turn the piston in to install the new pads with ease.

Oh - then I’d be inclined to say that the real problem is certainly elsewhere. Something is causing that wheel to drag, wearing out the pads, overheating everything, probably killing the caliper seals, and wrecking the caliper. The 2 most likely things would be the brake line and/or the parking brake mechanism.