I am trying to diagnose a strange problem with the brakes on my 2001 Ford Windstar. When the pedal is depressed, we hear a sound from under the dash board that kind of sounds like something rubber being twisted or stretched, kind of a loud rubbery sqeaking sound. This isn't the pads or shoes. Definitely inside the car. I have the Ford Extended warranty and the dealer has replaced the brake booster three times so far. However, that hasn't made any difference at all. They tried to tell me that it's normal but it didn't do it when we bought the car and only started in the last 18 months or so.
Supposedly, it's the rubber bellows inside the booster making the noise. But, since we're on our third replacement so far, I'm beginning to wonder. What else could be causing this noise? If it is coming from the booster, is there anything else that could be causing the booster to make that noise? I found a post on Edmunds that suggested that the problem is actually with the master cylinder, but can't say for sure. And, I'm not sure how to convince the dealer that that is what the problem is.
It's worse when the weather is warm and when the problem really gets bad, the brake pedal gets hard to press, as if there is a lot of resistance.