Brake help...please
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New User
Joined: Sep 2004
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Brake help...please
Hello everyone. I have a 1992 F 150, 2 wd, 6 cyl that I just replaced pads, shoes, drums, rotors, some brake lines, power brake booster and the master cylinder on. I have bled the lines, twice actually, all the way up to the master cylinder. Why is it that when I do not have the motor running I have great brake pedal, and when you start her up the pedal fades to nothing ??? I am very perplexed and quite lost. I NEED HELP !!! All input extremely appreciated.
Thanx
MJ
Thanx
MJ
Elder User
Joined: Feb 2004
Posts: 855
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From: Ocean Park WA
Power bleeding works the best and start at the master, left front, right front, left rear then the right rear. I also have gravity bled the same way but it takes longer and you have to wait till you get a solid clear stream (same order). Check your rear brake adjustment, should have light drag when you spin it by hand, and also verify the calipers are filled and working correctly, use your significant other and have them push the brake pedal and rap on the caliper with a rubber mallet. Some times it just takes a couple of pedal applications to get all the cylinders filled.
Elder User
Joined: Feb 2004
Posts: 855
Likes: 0
From: Ocean Park WA
If it will pump up and slowly drop you have a leak, if it will pump up and hold its air in the system. I worked for U-Haul for a couple of years driving service truck and we would have similar problems sometimes the first time you apply the brakes after putting new calipers or wheel cylinders I've had several go straight to the floor. It does feel like the brakes are working with the engine off but it's just because the booster is not helping to apply the brakes. Disk brakes need a lot of hydraulic pressure to work hence the booster.
