F150 thumping noise.

wolverine6wolverine6 Member Posts: 2
edited March 2014 in Ford
Why is it that when I partially depress my brake I get a thumping noise under the hood, when I fully depress it it stops? I checked the calipers and rotors and they look fine, the wheels don't shimmy or anything so I figure it is something under the hood just can't tell what.


  • wolverine6wolverine6 Member Posts: 2
    How do I trouble shoot my master cylinder for a booster problem?
  • alcanalcan Member Posts: 2,550
    Operational test: with engine off, pump brake pedal until all vacuum is depleted from booster and pedal is hard. Hold pedal down and start engine. Pedal should drop some.
    Leakage test: Run engine. Without stepping on brake pedal, shut engine off. Wait 2 minutes then with engine off apply brakes. Should be enough reserve vacuum in booster for 2 brake applications.
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