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Break problem question

Old Dec 26, 2013 | 08:46 PM
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Break problem question

When driving my 79 my break pedal went almost to the floor before it began to stop the truck, fluid checked out fine, so what could be the problem? Booster? Master cylinder?
 
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Old Dec 26, 2013 | 08:51 PM
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Booster bad would cause a hard peddle . Master bypassing is my first thought . Did the brakes work fine afterwards ? If so , likely master cyl.
 
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Old Dec 26, 2013 | 09:05 PM
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Originally Posted by JWC 3
Booster bad would cause a hard peddle . Master bypassing is my first thought . Did the brakes work fine afterwards ? If so , likely master cyl.
No I believe it was more of a gradual process, it started to feel like I had to press the pedal down more, and them after awhile it was almost too the floor before it stopped
 
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Old Dec 26, 2013 | 09:09 PM
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Are any of your brakes dragging ? They can drag and boil the fluid causing loss of peddle .
 
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Old Dec 26, 2013 | 09:36 PM
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Generally a low pedal after service involving opening up the brake lines indicates air in the system. Often pumping the brakes will give a higher pedal if this is the case. The fix is to bleed completely.

If there was no service involved and it got worse over time, probably a bad master as posted above. Time for a new one.
 
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Old Dec 26, 2013 | 09:45 PM
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Originally Posted by 1979 300i6
No I believe it was more of a gradual process, it started to feel like I had to press the pedal down more, and them after awhile it was almost too the floor before it stopped
Sounds like failing cup seals. Time to rebuild/replace the master cylinder.
 
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Old Dec 26, 2013 | 09:49 PM
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Thank you all for the advice, looks like it's time for a new master cylinder
 
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