Rear Calipers Won't Decompress

[CheckTheGate]

Hello all! I am in the process of changing all of my rotors and pads. I changed my driver's side front rotor and pads, and then moved to the driver's side rear tire. I got the caliper and rotor off just fine, but I can't get my caliper to decompress.

I thought it may be because I didn't pump the brakes after changing the first tire, so I pumped the brakes a little and brake fluid shot out all around the piston. I tried to use my c-clamp again, no luck. It won't budge. So now I guess I need to add more brake fluid to replace what I lost.

Any ideas?? Also, where do I add brake fluid? Is that something that is easy to do?

Thanks in advance!

 

[swshawaii]

so I pumped the brakes a little and brake fluid shot out all around the piston.

Even if you got the pistons to "decompress", it's a leaking piston seal most likely caused by damaged bore walls. Always a good idea to open the bleeders to flush out contaminants before compressing the pistons. How does the outer dust boot look? Rather than trying to rebuild with a caliper repair kit, check out the NAPA Total Eclipse calipers. Reasonably priced, lifetime warranty, powder coated, and usually local stock.

http://www.napabrakes.com/magnoliaPublic/home/products/calipers/total-eclipse-loaded-calipers.html

 

[CheckTheGate]

I'm just now learning how to do all of this, so please excuse my ignorance. I'm not exactly sure what a dust boot is. I looked it up, so I'll go check it out.

But more than likely it sounds like I need to replace my calipers.

 

[koda2000]

you can't get them to compress because they don't just press in like the fronts. rear caliper pistons screw in. there's a special tool to do this with. you can borrow it from most auto parts stores.

BTW, they may be leaking because the pistons are screwed OUT to far, so you may find you don't need to replace/rebuild them.

 

[swshawaii]

You sure koda? I recently "attempted" to rebuild my rear calipers.

http://www.scribd.com/doc/241092952/Caliper-Disassembly-and-Assembly

 

[koda2000]

You sure koda? I recently "attempted" to rebuild my rear calipers.

http://www.scribd.com/doc/241092952/Caliper-Disassembly-and-Assembly

every car and truck I've ever owned (including my daughter's 2000 Mustang) had rear calipers whose pistons screwed in. I honestly have not had to replace rear pads on any of my Explorer'/Mountaineer's, but i'm pretty sure the pistons screw in. one way to tell is if the piston appears solid, rather than hollow, and has small indentations cast into it's face for the tool.

 

[swshawaii]

They're hollow.

http://www.rockauto.com/catalog/moreinfo.php?pk=2042154&cc=1362451

http://www.rockauto.com/catalog/x,carcode,1362451,parttype,1704

 

[koda2000]

They're hollow.

http://www.rockauto.com/catalog/moreinfo.php?pk=2042154&cc=1362451

http://www.rockauto.com/catalog/x,carcode,1362451,parttype,1704

we'll if they're hollow, the pistons should just press in. maybe it's because of the way the parking brake works on the Explorer. I don't recall if the Mustang parking brake used the same design.

Explorer rear caliper:

http://contentinfo.autozone.com/znetcs/additional-prod-images/en/US/fen/C576/2/image/3/

Mustang rear caliper:

http://contentinfo.autozone.com/znetcs/additional-prod-images/en/US/fen/C394/2/image/3/

 

[Bobmbx]

every car and truck I've ever owned (including my daughter's 2000 Mustang) had rear calipers whose pistons screwed in. I honestly have not had to replace rear pads on any of my Explorer'/Mountaineer's, but i'm pretty sure the pistons screw in. one way to tell is if the piston appears solid, rather than hollow, and has small indentations cast into it's face for the tool.

I've done the rears on my 06, and they push in.

 

[swshawaii]

Wow folks, koda's human after all. IMO, he's more accurate than the Ford Workshop Manual! LOL

 

[Turdle]

Yeah the rears do compress, unless they are seized as the OP's are.

You add fluid in the brake reservoir under the hood. keep it filled while working on your calipers, as when you remove the caliper fluid will start to flow.
If the reservoir runs dry and air enters the line to the ABS you are screwed. You'll have to have the abs pump bled. So, have a friend keep an eye on the brake pluid level while you change the caliper. Once the caliper is hung, loosen the bleeder valve and fluid should start to flow again filling the caliper--keep reservoir full. once you see fluid escape the bleeder close it. If you get a pair of calipers, remember the bleeder valve should be on the high point, don't install them backwards ( side to side are different)

You will then need to bleed the brakes.

However, I suggest you have this performed by a professional , not trying to be mean, just looking out for your safety. A few things you asked make me skeptical about your safe success. No offense.

 

[Dan Whitaker]

Did you siphon some of the brake fluid out on the master cylinder? When you compress the pistons it pushes the brake fluid back into the master cylinder. If it's full of fluid you are not going to be able to compress the pistons.

 

[koda2000]

we'll if they're hollow, the pistons should just press in. maybe it's because of the way the parking brake works on the Explorer. I don't recall if the Mustang parking brake used the same design.

Explorer rear caliper:
http://contentinfo.autozone.com/znetcs/additional-prod-images/en/US/fen/C576/2/image/3/

Mustang rear caliper:
http://contentinfo.autozone.com/znetcs/additional-prod-images/en/US/fen/C394/2/image/3/

ok, I stand corrected.

 

[swshawaii]

Reading the OP again, sounds like the piston came out. Agree with Turdle and see a specialist, or buy a rebuilt semi loaded caliper.

 

[Turdle]

ok, I stand corrected.

Man, it's all good. You are a tremendous helper around here.

 

[Flash]

ok, I stand corrected.

The rear calipers that have screw type pistons don't have parking brake shoes.
There's a lever that the handbrake cable pulls on that rotates the piston to screw it in to clamp the disc.

 

[koda2000]

Man, it's all good. You are a tremendous helper around here.

Thanks for the kind words. Hey, I'm the first to admit when I'm wrong, unlike my dad who was fond of saying, "I thought I was wrong once, but it turned out I was mistaken".

 

[Bobmbx]

Thanks for the kind words. Hey, I'm the first to admit when I'm wrong, unlike my dad who was fond of saying, "I thought I was wrong once, but it turned out I was mistaken".

I am never wrong. I am, at times, misinformed.

And I am never late. I was needed elsewhere.

 

[J_C]

To summarize what's been posted so far, do not pump the brakes or add more fluid yet. If you can't get the piston in, first take a toothbrush and scrub away the grime around the piston and boot, then loosen the bleed valve and try to compress it again. If it simply won't budge you need a new caliper.

After whichever you do you need to bleed that line before tightening the valve closed, after topping off the brake fluid in the reservoir. It's located under the hood and should be labeled, is an oval white container roughly 12 ounces in size.

When finished if the brake pedal feels spongy after it's running and pedal pressed, then some time elapes, you need to bleed the line again. Make sure all the fluid is cleaned up so none gets on the pads or disc.

 

[CheckTheGate]

Thanks everyone! I finally got all of my rotors and pads changed. I only had to replace one of my calipers. I made sure that I went through the complete bleeding process and everything seems to be working just fine.

Again, thank you all for your suggestions and tips. This is one of the best forums I've ever found. Being somewhat new to a lot of maintenance issues I've had to deal with recently, it's nice to have a place to get support and a little criticism at times.

Cheers!