I have a 2010 Honda CR-V. I was trying to change the brake pads. I cannot compress the brake caliper piston. I used an 8 inch clamp, no luck. Any suggestions?

 

Did you try opening the brake fluid reservoir?

 

Yes I did. Still very as hard as rock.

 

Taking the lid off the master cylinder won't help a whole lot, but cracking open the bleeder often will. In this case though, since it looks like one of the pistons retracted just fine, the issue is probably rust between the other piston and the bore. Try using a tiny screwdriver or a pick tool to pull the boot out of the piston groove and spray some rust penetrant down the sides of the piston. Let it sit for a bit and then try again to compress the piston. If that doesn't work, I've found that those large welder's vice grips work even better than a c-clamp. They work extremely well for single-piston calipers...less so for dual-piston because ideally you want to compress both pistons at the same time...like you're doing in the picture...but with one already compressed you could use the vice grip to just focus on the stuck one.

 

Thank you for the tips. I did not crack open the bleeder. But I sprayed a little WD-40 (hopefully using this instead of a rust penetrant is not a big mistake) in the piston groove. Than rotate the piston using a plyer. Then tried compressing again and it worked. Thanks again for the advice.

 

I'm glad to hear you got your piston un-stuck, but just for future reference (or anyone else reading this thread), it's never a good idea to grip the piston on its outside surface with a metal jaw like pliers. The outside surface is precision machined because it rides against a seal (the seal that keeps brake fluid from pushing past the piston instead of just pushing on the piston), and if the outside of the piston is scored in any area where the seal rides against it, it'll degrade the seal and diminish braking effort as your fluid leaks out! If you absolutely must use pliers on the outside of the piston, wrap the piston in a rag or something first to protect the finish.

 

That's a lot of corrosion too. Are you in Minnesota?