help with hard brake pedal problem

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May 18, 2011 | 07:27 PM

98SVTCobra

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From: Hayden, AL

help with hard brake pedal problem

I just bought a 77 F150 with a 400. With the engine running or off the brake pedal is stiff and stays on the floor. The pedal moves slightly with engine running as if its getting some vacuum but stays close to floor and feels like pushing on a brick wall haha. The truck will stop but you have to really stand on the pedal and pull it back up with hand or foot.
Master cylinder is full, front brake pads are good, rear drums have decent shoes.

May 18, 2011 | 08:21 PM

VocaTexas

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Sounds to me like you need a new vacuum booster. On my F-150, when the diaphragm failed I could hear it sucking air when I stepped on the brake.

May 19, 2011 | 08:04 AM

98SVTCobra

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From: Hayden, AL

I dont hear any air leaks when I press brakes but it is loud under the hood. Haha, Anyone else have thoughts on this?

May 19, 2011 | 08:41 AM

PA74F250

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From: York, Pa

I would seem to think the pedal should be off the floor even if the vaccum booster is bad.

May 19, 2011 | 08:09 PM

98SVTCobra

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From: Hayden, AL

I fixed the problem today. I started by bleeding the brakes and found lots of rust in the rear lines. I bleed to brakes several times and added new fluid.