squishy brake pedal

Your chassis is over 20 years old so you should be looking hard at those brake lines. If any part of them is rubber, the fluid might be expanding the hose rather than pushing the piston in the caliper. Just a thought.

RLS7201 wrote:

John&Joey wrote:
Pumping up normally means you have a bad gasket somewhere in the brake system. But, with that said....

The older 460 F53 was know to generate a lot of heat and boil the brake fluid. Fresh fluid is a yearly must, plus look for the highest quality/boiling point that will work in your system without damage to it.

I would really like to know where that gasket might be, so I can make sure mine is not leaking.

Richard

:B
It's behind the buckle for the fan belt.
(Sorry John)

I would suggest getting it fixed sooner rather than latter, I had a car about 20-25 years ago (it was an '89 Ford with over 100,000 miles at that point), brakes felt a bit off on the way home from work one night, at the first intersection I just thought something felt a little off, at the second one I was sure, at the third one the pedal went to the floor and and I blew through it without slowing down. Thankfully there was no cross traffic and by then I was only a few hundred feet from home, so I used the hand brake to limp home at about 15 mph. In case you have not guessed it by now, the master cylinder failed.

John&Joey wrote:
Pumping up normally means you have a bad gasket somewhere in the brake system. But, with that said....

The older 460 F53 was know to generate a lot of heat and boil the brake fluid. Fresh fluid is a yearly must, plus look for the highest quality/boiling point that will work in your system without damage to it.

I would really like to know where that gasket might be, so I can make sure mine is not leaking.

Richard

On the V10 chassis the Owner's Manual says that the break fluid should be replaced every other year.

An auto mechanic friend of mine was rebuilding a wrecked Ford F150 and had a very similar problem. He went thru everything - bled the lines, replaced the booster, double checked all the adjustments, replaced brake lines, etc. He was able to isolate the problem to the rear brakes but was still stumped. He finally assembled a brake line bleeder system with a much larger tank and tired bleeding the rear brake lines with it and that solved the problem.

Pumping up normally means you have a bad gasket somewhere in the brake system. But, with that said....

The older 460 F53 was know to generate a lot of heat and boil the brake fluid. Fresh fluid is a yearly must, plus look for the highest quality/boiling point that will work in your system without damage to it.

Having to "pump up" the brakes to slow down is a classic symptom of a bad/worn master cylinder. I had a car that developed that exact problem (with those symptoms) once, and needless to say I had it repaired as soon as I could. It might be worthwhile to double-check that everything is fully bled.

I understand that these chassis have hydroboost brakes rather than vacuum assist brakes. Problems with the booster portion won't cause the problems you describe; they might very well cause limited braking power and strange pedal feel, but without improvement with the next pedal press.

You likely have a bad master cylinder coupled with either low vacuum or a bad vacuum booster.

Make sure the power steering reservoir is full, and make sure you're using fresh brake fluid with all of the old fluid flushed out. I prefer the higher boiling point of DOT 5.1 (NOT DOT 5!) fluid over the lower numbers.