Brake Fading!!

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Feb 26, 2006 | 10:59 AM

Lucky Charms

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From: Pennsylvania

Brake Fading!!

1985 Ford f250 has a brake pedal that fades & is spongee.I have blead the brakes but the pedal still fades away.Could it be the master cylinder or booster??any help would be great.

Matt

Feb 26, 2006 | 05:23 PM

PMDRACER

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Assuming you don't have a leak, it's definitely the master cylinder.

Make sure when you get the new one you bench bleed it before installing it on the truck.

Mar 5, 2006 | 04:17 PM

Lucky Charms

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Thank you for your response.I have changed the master cylinder.I have changed the front calipers & the two rear cylinders.I have bled the system from its furthest point to the master cylinder all with a steady stream of fluid.Hears my problem! After bleed it the system the brake pedal is only two inches of the floor & after a few minutes of not pumping the pedal it goes straight to the floor on the first pump. Whats next?I have thought it was the power booster all along! What do you folks think??

Matt

Mar 6, 2006 | 05:22 PM

Lucky Charms

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Is There No Answer!!

Any help would be geat!!!Thank you for your response.I have changed the master cylinder.I have changed the front calipers & the two rear cylinders.I have bled the system from its furthest point to the master cylinder all with a steady stream of fluid.Hears my problem! After bleed it the system the brake pedal is only two inches of the floor & after a few minutes of not pumping the pedal it goes straight to the floor on the first pump. Whats next?I have thought it was the power booster all along! What do you folks think??

Mar 6, 2006 | 06:13 PM

PMDRACER

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I'm not a Ford guy, mostly Pontiac and GM. If it were my GTO, I'd be blaming the combination (aka proportioning) valve, but these trucks don't have one in the traditional sense.

When you bleed the brakes, are you getting a full heavy stream out of each bleeder every time? A low pedal is not a characteristic of a dead vacuum booster. A heavy pedal is more like it.

Are you sure they gave you the correct disc/drum master cylinder? If the guy gave you a disc/disc master cylinder, that would explain some of the symptoms.

Mar 6, 2006 | 06:46 PM

Lucky Charms

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Yes heavy stream of fluid out of all four point as well as from the master cylinder.On the rear axel the brake lines go into some kind of devise! I have no Idea what it is or what it does.Maybe this could be the problem??

Matt

Mar 7, 2006 | 06:39 AM

LargeMarge

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Does the truck have rear ABS brakes. The device could be the ABS hydraulic unit. I dont know what year they started rear ABS. My 89 has rear ABS and that hydraulic unit was rusted into the open position so the truck acted as if I had no rear brakes. Also, did you bu a new or remanufactured master cylinder. Sometimes reman masters are junk when you buy them. Find two plugs and unhook both the lins coming of the master and plug both of them. If the pedal is hard then the master is good, if the pedal is still soft, bad master.