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Home >> Pontiac >> 1991 >> Grand Prix V6-191 3.1L >> Repair and Diagnosis >> Maintenance >> Brake Bleeding >> Service and Repair >> Master Cylinder Bleeding >> Powermaster III Bleeding >> Pressure Bleeding

Pressure Bleeding

NOTICE:
- If a Powermaster III Unit has been replaced, or if air has entered (or is suspected in) the brakelines, the entire brake system (Powermaster III, lines, and calipers) must be bled at each wheel brake.
- If only a hydraulic part of the Powermaster III Unit has been replaced (bleeder valve, relief valve, tube and nut assembly, accumulator, reservoir, solenoid, or pressure switch), and air has not entered the brake lines, it may only be necessary to bleed the Powermaster III Unit by performing an "ABS Solenoid Bleed and Checkout Test" using 94-00101-A or by bleeding the booster section of the Powermaster III Unit at the bleeder valves.
- Performing an "ABS Solenoid Bleed and Checkout Test" or bleeding the Powermaster III Unit at its bleeder valves will not remove air from the brake lines.

PRESSURE BLEEDING PROCEDURES

Tools Required:
- J 37115 Bleeder Adapter
- 094-00008-A Tech 1 Cartridge

NOTICE:
- Pressure bleeding equipment must be of the diaphragm type. It must have a rubber diaphragm between the air supply and the brake fluid to prevent air, moisture and other contaminants from entering the hydraulic system.
- Use only DOT 3 brake fluid from a sealed container. Do not use any suspect or contaminated (wet, dirty, etc.) fluid. Do not use DOT 5 silicone fluid.

Important
- Make sure vehicle ignition is off, unless otherwise noted. This will prevent the Powermaster III pump from starting during the bleeding procedure.

1. Depressurize the Powermaster III Unit, refer to "Depressurizing the Pawermaster III Unit".
2. Clean and remove reservoir cover and diaphragm assembly.
3. Check brake fluid level in both reservoir sections and fill to the correct level if necessary, using clean brake fluid.
4. Install J 37115 and secure with attachment cable. Make sure attachment cable does not interfere with access to bleeder valves or bend pump motor bracket on the Powermaster III Unit.
5. Attach J 37115 to pressure bleed equipment and charge to 34-69 kPa (5-10 psi) for approximately 30 seconds, inspect sealing area for leaks. When no leaks exist, slowly increase pressure to 207-241 kPa (30-35 psi). Pressure of 136-171 kPa (20-25 psi) is O.K., but a pressure of 205-240 kPa (30-35 psi) is more desirable.

Important
- If the pressure bleeding equipment being used will not reach 207-241 kPa (30-35 psi), the equipment can still be used if at least 138 kPa (20 psi) is reached, longer bleeding times should be used.

6. Bleed J 37115, place a rag over valve while depressing it to absorb any venting fluid.
- Depress ball to open bleeder valve on top of J 37115 until fluid flows without air.
7. Raise vehicle and suitably support it.

Important
- Bleed Sequence:
- Right Rear, Left Rear, Right Front and Left Front.

8. Bleed wheel brakes in sequence shown above.
- Attach bleeder hose to bleeder valve and submerge opposite end in a clean container partially filled with brake fluid.
- Slowly open bleeder valve and allow fluid to flow until no air is seen in fluid.
- Allow brake fluid to flow for at least 20 to 30 seconds at each wheel when checking for trapped air.
- To assist in freeing trapped air, tap "lightly" on caliper castings with a rubber mallet.
- Close valve when fluid begins to flow without air bubbles.
9. Lower vehicle
10. Bleed Powermaster III isolation valves.
- Attach bleeder hose to bleeder valve on inboard side of Powermaster III Unit and submerge opposite end in a clean container partially filled with brake fluid.
- Slowly open bleeder valve and allow fluid to flow until no air is seen in fluid.
- Close bleeder valve when fluid begins to flow without air bubbles.
- Repeat procedure on outboard side bleeder valve.
11. Remove 3 37115 from Powermaster III Unit.
12. Check brake fluid level in both reservoir sections and if necessary, fill to the correct level using clean brake fluid.
13. Replace reservoir cover and snap all four cover tabs in place on reservoir.
14. Manually apply brake pedal with a jabbing (sharp, rapid apply) motion 3 times.
15. Bleed booster section of the Powermaster III Unit.

NOTICE:
- Turn the ignition off if the pump motor runs for more than 60 seconds, refer to "Pump Runs Continuously".

- Connect 094-00101. Turn the ignition to run, without starting the engine, and allow the pump to pressurize the accumulator. When the pump has stopped, perform the "solenoid bleed and check out test".

Important
- If 094-00101 is not available, depress the brake pedal with moderate pressure and turn the ignition key to "Run" without starting the engine for 3 seconds. Repeat this "Off/Run" procedure 10 times to cycle the solenoids.

16. Bleed accumulator.

NOTICE:
- Do not check brake fluid level without fully depressurizing the Powermaster III Unit or overfilling will result.

- Turn the ignition off and depressurize the Powermaster III Unit. Wait two minutes for air to clear from the brake fluid in the reservoir.
- Check fluid levels by removing cover and repeating steps 12 and 13.
17. Turn the ignition to "Run" without starting the engine and allow the pump motor to pressurize the accumulator.

Inspect
- Apply brake pedal and note brake pedal feel and travel.
- If brake pedal feel is soft or spongy or brake pedal travel is excessive, refer to "Excessive Pedal Travel".
- If a "bump" is noted upon initial brake pedal apply or pedal apply does not feel smooth and uniform, refer to "Non- Uniform Pedal Apply".

18. Road test vehicle and note brake pedal travel and feel. If any symptoms described above in "Inspect" appear, refer to the appropriate section.
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