Spongy Brake Problem
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Freshman User
Joined: Feb 2010
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Spongy Brake Problem
I have an 89 F150 5.0 4x4. A month ago I changed the rear brake cylinders. I bled all the brakes as I normally do and everything was fine. The other day I hit the brakes, the truck stopped but the pedal went to the floor. I brought it home and bled the brakes again thinking it still had air in the lines but it didnt help. The strange thing about this is when the truck is turned off the pedal feels fine but when I start it the pedal goes to the floor. Anybody have any ideas whats going on?
Elder User
Joined: Feb 2002
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From: Portage Twp, PA
With the truck running, can you pump the pedal a few times quickly and get a solid pedal for a few seconds, then it sinks to the floor?
Could be other issues if you have other symptoms. But if what I've described is the case, it's most likely a bad master cylinder.
Pat
Could be other issues if you have other symptoms. But if what I've described is the case, it's most likely a bad master cylinder.
Pat
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Freshman User
Joined: Feb 2010
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Ok today I replaced the booster but it didn't fix the problem. So far in the last month I've replaced the booster, both calipers and both rear wheel cylinders. The master cylinder was replaced before I bought it in January but not sure how old it is. Just know that its not original. Also there is no leak. The reservoir is full to the max line and I've never had to add any fluid. The front brake lines are old but don't appear to flex at all when we were bleeding them but I think I will replace them tomorrow since I've done everything else. What else is there to check?
Posting Guru
Joined: Dec 2009
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From: Calverton
Spongy Brake Problem normaly indicates air in the system...are you using a piece of hose from the bleeder, to a jug, hose end submerged with brake fluid in it? are you bleeding the furthest bleeder first
Post Fiend
Joined: Jan 2005
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When you bled the brakes did you bleed the RABS module on the inside of the left side frame rail? If not you probably have air trapped there.
There is a bleed screw on it and it just bleeds like a wheel cylinder.
There is a bleed screw on it and it just bleeds like a wheel cylinder.
