Need brake help
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Banned
Joined: Feb 2006
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Need brake help
I have a 99 f-250 Super duty with Hydro-boost brakes. Lost all but a little brakes on the floor. Had a weak power steering pump and thought maybe that affected the hydro-booster. Replaced it with no change in brakes. If I'm sitting still and turn steering wheel I have good brakes and if I hold them they won't bleed down. If I let off and hit them again I have no brakes again. Is this an indication of a bad booster or is my master cylinder bad. This is my first post. Hope I'm not out of line. Thanks.
Fleet Mechanic
Joined: Feb 2005
Posts: 1,797
Likes: 1
From: Northern Colorado
Check the fluid level and if low, check the system for visual signs of leakage. If that's OK, then I would suggest you try bleeding your brakes and make sure you have no air trapped in the lines. If still no change, I would suspect the master.
Posting Guru
Joined: Oct 2004
Posts: 2,244
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From: Morgantown WV
Start and run the engine.
Stop the engine.
Apply the brakes. The accumulator in the Hydro-Boost power brake booster should retain enough pressure for at least two power assisted brake operations. If no power assist is felt, replace the Hydro-Boost power brake booster and retest the system.
Stop the engine.
Apply the brakes. The accumulator in the Hydro-Boost power brake booster should retain enough pressure for at least two power assisted brake operations. If no power assist is felt, replace the Hydro-Boost power brake booster and retest the system.
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Banned
Joined: Feb 2006
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Appreciate your help. I willhave a new master cylinder tomorrow but got to thinking since I have good pedal when sitting still and turning the wheel that the hydo booster was the problem and just asking someone elses opinion. Probably should go ahead and replace that while I'm there huh? Thanks again for the response
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...Welcome Jody King to Ford Truck Enthusiasts!
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We are happy you have chosen the best source for Fords.
Enjoy FTE....and
JOIN CLUB FTE -SUPPORT THE FORUMS!
…..See you on the boards.
Laughing Gas
Joined: Jul 2003
Posts: 1,157
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From: Littleton, Colorado
Sounds to me like you're thinking right. Symptoms sound like you have a bad valve(s) and the accumulator in your hydro boost is toast. I would flush your P/S system and install a new hydro boost. I had similar problems. I replaced the hydro boost and all is well now.
Good luck and welcome to FTE,
Austin
Good luck and welcome to FTE,
Austin
Fleet Owner
Joined: Jun 2004
Posts: 25,090
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From: Rio Rico, AZ.
Can you pump it up while driving and have a good pedal?
I've seen a loose wheel bearing spread the caliper and give a very low pedal until the driver pumps it back up again. Then the brake pedal is high for the duration of the stop.
I've seen a loose wheel bearing spread the caliper and give a very low pedal until the driver pumps it back up again. Then the brake pedal is high for the duration of the stop.
