My right front caliper locked up while driving. I replaced it and it worked fine for a year (in frequent use). The new caliper started intermittently locking up now. I also get a noticeable hissing sound coming from near the brake pedal...like air leaking out. Not sure how the power assist works on these (PFM: pure F magic?). Brake pads fine and so is fluid level. Hoping to do myself...the ol girl hasn't been to a professional in over 10 years...

 

Could be the hose to that caliper. They sometimes break down inside and don't allow the pressure to release immediately. That's where I would go first.

 

good idea. if that's it, hope it didn't contaminate caliper. tomorrow will check how hard it is to replace for an amateur.

any ideas on the air / hiss by the break pedal? Still hisses sometimes when foot is just OFF the pedal. Thanks!.

 

I got a constant hissing noise while driving my bronco due to a vaccum leak in the brake booster once. Hope that helps lol

 

inside the cab where the brake pedal linkage goes thru the floor, there is a plastic piece (back of vacuum component which under hood has master cylinder mounted on it) that started to breakdown with age...several cracks allow air leak and hissing noise. I slapped some RTV on it until get the money to replace.

Brakes work fine after replacing the old caliper HOSE.

Thanks to all.