Pressure Bleeding

1987 Chevrolet Hi-Cube 6.2 J, 475/M40SECTION Pressure Bleeding
WARNING: This page does not describe the selected car, but rather 35 other vehicles, including the 1992 Pontiac Trans Sport, 1992 Oldsmobile Silhouette, 1992 Oldsmobile Bravada, 1992 GMC Yukon, and 1992 GMC Vandura Special. However, it is still accessible from the selected car via links, so may be relevant.
NOTE: Air tends to cling to caliper walls. When bleeding vehicles with disc brakes, lightly tap caliper to help remove air. DO NOT use rigid clamp to position hold-off valve stem. This may damage valve assembly, causing brake failure.
  1. Retain hold-off valve stem of combination valve using Valve Retainer (J-23709). See Fig 1. This allows brake fluid to flow through combination valve and entire system during bleeding.
  2. Clean master cylinder cap and surrounding area. Remove cap. With pressure tank at least 1/2 full, connect pressure bleeder to master cylinder with adapters. Attach bleeder hose to first bleeder valve to be serviced. See BLEEDING SEQUENCE under BLEEDING BRAKE SYSTEMΒ .
  3. Place other end of hose in glass jar partially filled with brake fluid so end of hose is submerged in fluid. Open release valve on pressure bleeder. Set pressure bleeder to 20-25 psi (1.4-1.8 kg/cm2 ) or pressure specified by equipment manufacturer.
  4. Open bleeder screw 3/4 - 1 turn and note fluid flow. Close bleeder screw when no air bubbles are present in fluid flow. Repeat procedure on remaining wheels in proper sequence.
  5. Check brake pedal operation. Remove pressure bleeder. Remove valve retainer from hold-off valve. Refill master cylinder reservoir, if necessary.
Fig 1: Positioning Hold Off Valve On Combination Valve (Typical)
G117380Courtesy of GENERAL MOTORS CORP.
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When to See a Mechanic

Stop DIY work and contact a certified mechanic immediately if any of the following apply:

  • β€’ You smell fuel, burning insulation, or see smoke.
  • β€’ Brakes feel soft, pull hard to one side, or make grinding noises.
  • β€’ The engine overheats, stalls repeatedly, or misfires under load.
  • β€’ You are missing required tools, torque specs, or safe lifting equipment.
  • β€’ You are not confident in the next step or safety outcome.