How to Fix a Proportioning Valve on a 1999 Chevy Cavalier

The 1999 Chevy Cavalier used a brake proportioning valve to route brake fluid to the front and rear wheels. The proportioning valve - as its name implies - proportions the brake fluid so that more fluid goes to the wheels that do the most braking. This is normally the front wheels, due to the fact that the vehicle is normally moving forward most of the time and inertia places heavy stress on the front wheels. While it is not common for a brake proportioning valve to fail, it does happen. To be sure, you should check the proportioning valve. If it has failed, the only way to fix it is to replace the entire unit.

Instructions

1

Open the hood and locate the brake proportioning valve. It should be located on the left side of the vehicle on the fender near the firewall. The brake proportioning valve will have four brake lines attached to it and a line coming from the brake master cylinder.

2

Slide the tube nut wrench over one of the brake lines on the back side of the proportioning valve. These lines are the lines that run to the wheels. Orient the tube nut wrench so that it fits over the tube nut.

3

Place the catch pan underneath the brake proportioning valve.

4

Loosen each tube nut running to the wheels by turning the nut counterclockwise. You can easily tell which brake lines run to the wheels (as well as which wheels) because you can follow the brake lines running off of the proportioning valve to their respective wheel.

5

Press on the brake pedal to see if any brake fluid leaks out into the catch pan. You may need an assistant for this job. If brake fluid is leaking into the catch pan, it is likely that the valve is operating normally, but there is no real way to check the actual specifications and volume of brake fluid being pushed through the valve for sure.

6

Check the fluid rate leaking from the valve. The fluid running to the front brakes should leak faster and with more volume than the fluid running to the rear brakes. If an excessive amount of fluid is running to the rear brakes, your proportioning valve needs to be replaced.

7

Mark the location of all brake lines with masking tape and a marker and remove all brake lines from the proportioning valve.

8

Remove the two retaining bolts that hold the valve in place and pull the valve out of the engine bay.

9

Bolt in the new proportioning valve and reattach all of the brake lines.

10

Take the Cavalier to a professional brake shop to have them verify your work and to bleed the system.