May 082015
 

Front brakes come on with out applying pedal.Brakes even came on while going up a hill. Any HELP would be appreciated. Thank You.

  One Response to “1979 GMC Dura Van 35 (motor home) w/hydraulic brake booster”

  1. First thing you should do is check the power steering fluid level. It is also is what provides the hydraulics to the brake booster.

    Hydro Boost Brake Troubleshooting Chart:
    —————————————-
    High Pedal and Steering Effort (Idle)
    1.Loosen/broken power steering pump belt
    2.Low power steering fluid level
    3.Leaking hoses or fittings
    4.Low idle speed
    5.Hose restriction
    6.Defective power steering pump

    High Pedal Effort (Idle)
    1.Binding pedal/linkage
    2.Fluid contamination
    3.Defective Hydro-Boost unit

    Poor Pedal Return
    1.Binding pedal linkage
    2.Restricted booster return line
    3.Internal return system restriction

    Pedal Chatter/Pulsation
    1.Power steering pump drive belt slipping
    2.Low power steering fluid level
    3.Defective power steering pump
    4.Defective Hydro-Boost unit

    Brakes Oversensitive
    1.Binding linkage
    2.Defective Hydro-Boost unit

    Noise
    1.Low power steering fluid level
    2.Air in the power steering fluid
    3.Loose power steering pump drive belt
    4.Hose restrictions

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