ParkAvenue 1997-1999

Pressure Differential (Proportioning) Valve

Print

Removal & Installation



Specific to:

Buick LeSabre 1986-1990

Buick Park Avenue 1996-1999

Oldsmobile Delta 88 1986-1988

Pontiac Bonneville 1987-1990

On non-ABS vehicles, these parts are installed in the master cylinder body. On ABS equipped vehicles, the proportioning valve is usually located new the fuel filter under the car on the right side.

If equipped with Anti-lock Brake System (ABS), ensure that the hydraulic accumulator is fully depressurized before disconnecting any hydraulic lines, hoses or fittings.

  1. If equipped with ABS, raise and safely support the vehicle.
  2.  
  3. Disconnect and plug the brake lines from the proportioning valves.
  4.  
  5. Remove the proportioner valve(s) and O-ring assembly.
  6.  



Click image to see an enlarged view

Fig. On 1987-90 non-ABS vehicles, the proportioning valves are mounted in the master cylinder



Click image to see an enlarged view

Fig. Location of the proportioning valve, and related components - 1987-90 vehicles with ABS

To install:

  1. Lubricate new O-rings and the external proportioner valve threads with clean brake fluid. Install new O-rings on the proportioner valve(s).
  2.  
  3. On non-ABS vehicles, install the new valve(s) into the master cylinder and tighten to 24 ft. lbs. (31 Nm).
  4.  
  5. On vehicles with ABS, install the new valve(s) to the brake line.
  6.  
  7. Connect the brake pipes to the proportioning valve(s), then tighten to 11 ft. lbs. (15 Nm).
  8.  
  9. If raised, carefully lower the vehicle.
  10.  


WARNING
Clean, high quality brake fluid is essential to the safe and proper operation of the brake system. You should always buy the highest quality brake fluid that is available. If the brake fluid becomes contaminated, drain and flush the system, then refill the master cylinder with new fluid. Never reuse any brake fluid. Any brake fluid that is removed from the system should be discarded.

  1. Refill the master cylinder and bleed the brake system.
  2.  
  3. Connect the negative battery cable.
  4.  

Specific to:

Buick LeSabre 1991-1999

Buick Park Avenue 1996-1999

Oldsmobile 88 1992-1999

Oldsmobile LSS 1996-1999

Pontiac Bonneville 1991-1999


WARNING
For 1994-99 vehicles with ABS, after bleeding the brake system you must perform an "Auto Bleed" sequence, using a Tech 1® or equivalent scan tool. If you do not have access to a suitable scan tool, your vehicle will probably have to be towed to a shop with the proper diagnostic equipment to have the procedure performed.

With Anti-Lock Brakes

Specific to:

Buick LeSabre 1991-1999

Buick Park Avenue 1996-1999

Oldsmobile 88 1992-1999

Oldsmobile LSS 1996-1999

Pontiac Bonneville 1991-1999

  1. Raise and safely support the vehicle.
  2.  
  3. Clean the proportioning valve and brake pipe connections with denatured alcohol or equivalent to be sure no contaminants enter the brake system during servicing.
  4.  



Click image to see an enlarged view

Fig. Exploded view of the proportioner valve location - 1995 vehicle shown



Click image to see an enlarged view

Fig. On vehicles such as this 1991 model, the proportioning valves are located near the fuel filter

  1. Use a flare nut wrench to disconnect the brake lines from the proportioning valve, then remove the proportioning valve from the vehicle.
  2.  

To install:

  1. Install the proportioner valve in the vehicle, then connect the brake line, using a flare nut wrench. Tighten the proportioner valve fittings to 11 ft. lbs. (15 Nm).
  2.  
  3. Carefully lower the vehicle.
  4.  

Without Anti-Lock Brakes

Specific to:

Buick LeSabre 1991-1999

Buick Park Avenue 1996-1999

Oldsmobile 88 1992-1999

Oldsmobile LSS 1996-1999

Pontiac Bonneville 1991-1999

  1. Disconnect the negative battery cable.
  2.  
  3. Remove the master cylinder fluid reservoir, as follows:
    1. Remove the master cylinder from the vehicle, and clamp the flange of the master cylinder body in a suitable vise. Clamp only on the flange, NOT on the master cylinder body.
    2.  
    3. Use a 1 / 8 in. punch to carefully drive out the spring pins, being careful not to damage the when driving out the pins.
    4.  

  4.  



Click image to see an enlarged view

Fig. Use a hammer and drift pin to carefully drive the spring pins out

    1. Remove the reservoir by pulling straight up, away from the cylinder body.
    2.  
    3. Remove the O-rings from the grooves in the reservoir. Discard the O-rings and replace with new ones during installation.
    4.  


  1. Remove the proportioner valve cap, then remove the O-rings and springs.
  2.  
  3. Remove the proportioner valve pistons. Use needle nose pliers to remove the pistons, but be careful not the scratch or damage the piston stems.
  4.  
  5. Remove the proportioner valve seals from the pistons.
  6.  
  7. Inspect the pistons for corrosion or deformation and replace if found.
  8.  



Click image to see an enlarged view

Fig. Exploded view of the master cylinder components, including the proportioning valves - non-ABS vehicles

To install:

  1. Lubricate new O-rings and proportioner valve seals with the silicone grease in the repair kit. Also, lubricate the stems of the proportioner valve pistons.
  2.  
  3. Install new seals on the proportioner valve pistons with the seal lips facing upward toward the cap assembly.
  4.  
  5. Install the proportioner valve pistons and seals into the master cylinder body.
  6.  
  7. Place the springs in the master cylinder body.
  8.  
  9. Install new O-rings in the groove in the proportioning valve cap assemblies.
  10.  
  11. Install the proportioning valve caps in the master cylinder body, then tighten the caps to 20 ft. lbs. (27 Nm).
  12.  
  13. Install the master cylinder fluid reservoir, as follows:
    1. Lubricate new O-rings and reservoir bayonets with clean brake fluid, then install the O-rings in the grooves in the reservoir. Make sure the O-rings are properly seated.
    2.  
    3. Install the reservoir to the master cylinder body by pressing it straight down by hand into the body.
    4.  

  14.  



Click image to see an enlarged view

Fig. Position the reservoir on top of the master cylinder and press it straight down into the body

    1. Drive the spring pins in to secure the reservoir, being careful not to damage the reservoir or cylinder body.
    2.  
    3. Remove the master cylinder from the vise, then install in the vehicle.
    4.  


 
label.common.footer.alt.autozoneLogo