How to Replace the Brake Master Cylinder on a 1997 Montana

In 1990, Pontiac introduced its first minivan, the Trans Sport. This van was unlike any other around, as it had a very shallow angle that ran from its hood all the way up its windshield, giving it a door-stop-like appearance. In 1997, Pontiac redesigned the Trans Sport, giving it a more contemporary design. The 1997 model year also brought about the first use of the Montana name as a trim level for the Trans Sport. Replacing the brake master cylinder on the Trans Port is relatively simple, but performing the bleeding process afterward is rather complex, thanks to the vans intricate antilock brake and traction control systems.

Instructions

Removal

1

Press and release the brake pedal four or five times to bleed off any reserve vacuum in the brake booster. Hold a small drain pan under the master cylinder, loosen the brake line-to-master cylinder fittings with a flare wrench and wait for the fluid to stop dripping from them. Remove the brake lines from the master cylinder.

2

Siphon out as much of the brake fluid from the master cylinder reservoir, using a clean turkey baster. Press and hold the unlocking button on the fluid level sensors wiring harness on the base of the master cylinder reservoir and unplug the harness.

3

Wrap the end of each brake line with a clean, lint-free cloth to prevent contaminants from entering the brake system.

4

Remove the two nuts securing the master cylinder to the brake booster using a ratchet and socket. Pull the master cylinder from the brake booster.

Bench Bleeding Master Cylinder

5

Set the new brake master cylinder into a bench vice with rubber jaw protectors.

6

Thread the bleeder tubes from a master cylinder bleed kit into the brake line ports. Snug the bleeder lines with a flare wrench. Fill the master cylinder reservoir to the Max line with new DOT 3 brake fluid. Bend the bleeder hoses so their ends are submerged in the brake fluid.

7

Using the metal dowel rod included with the bleeder kit, press and release the plunger on the rear of the master cylinder. As you press and release the plunger, watch the hose ends in the brake fluid. Pump the plunger until no air bubbles come from submerged ends of the bleeder hoses.

8

Remove the bleeder hoses from the master cylinder and wipe up any fluid spills with a clean, lint-free cloth. Tighten the cap onto the master cylinder reservoir. Remove the master cylinder from the vice.

Installation

9

Guide the master cylinder onto its mounting studs on the brake booster and hand-thread the nuts. Remove the cloths from the brake lines. Press the brake lines into their respective ports in the master cylinder the lines are hard formed to prevent incorrect connection. Thread the brake line fittings just a few turns by hand.

10

Tighten the master cylinder nuts to 20 foot-pounds with a torque wrench and socket. Tighten the brake lines to 15 foot-pounds with a torque wrench and crows foot attachment.

11

Bleed the brakes.

Brake Bleeding

12

Find the antilock brake modulator to the drivers side of the master cylinder. Press a 1/4-inch-diameter rubber hose onto the bleeder valve the 1/4-inch metal valve on the rear of the ABS modulator. Set the free end of the hose into a clean, clear container and pour new DOT 3 fluid into the clean, clear container until the end of the hose is submerged.

13

Loosen the rear bleeder valve on the ABS modulator, using a combination wrench, and instruct an assistant to press the brake pedal slowly to the floor. Watch for air bubbles to come from the submerged end of the hose. Tighten the bleeder valve and instruct the assistant to release the brake pedal. Repeat this step until no air bubbles come from the ABS modulator.

14

Repeat steps 1 and 2 on the front bleeder valve on the ABS modulator.

15

Remove the 1/4-inch rubber hose. Refill the master cylinder reservoir to the Max line with new DOT 3 brake fluid.

16

Locate the traction control system modulator, the hydraulic component on the front drivers side of the engine compartment. Remove the bolt securing the TCS modulator to its bracket, using a ratchet and socket and pull the TCS modulator away from the bracket to see across the bleeder valves.

17

Press the 1/4-inch-diameter hose onto the drivers side bleeder valve on the TCS modulator and set the other end of the hose in the clean, clear container, so the end of the hose is submerged in the brake fluid. Loosen the bleeder valve and instruct an assistant to press the brake pedal to the floor slowly. Watch the submerged end of the hose for bubbles. Tighten the bleeder valve and tell the assistant to release the pedal. Repeat this step until no bubbles come from the hose.

18

Repeat step 6 on the passengers side bleeder valve.

19

Hand-thread the TCS module-to-bracket bolt to hold the module in place. Remove the 1/4-inch rubber hose and refill the master cylinder reservoir.

20

Refill the master cylinder to the Max level with DOT 3 fluid.

21

Raise the rear of the Montana with a floor jack and slide jack stands under its rear suspension crossmember. Raise the front of the van of the ground with a floor jack and slide jack stands under the Montanas subframe. Lower the front of the van onto the jack stands.

22

Crawl under the vehicle, so you are just behind the right rear wheel. Find the bleeder valve near the top of the brake caliper and press the 1/4-inch-diameter hose onto the bleeder valve. Set the free end of the hose into the clean clear container with Dot 3 brake fluid, submerging the end of the hose in the fluid.

23

Loosen the bleeder valve and instruct your assistant to press the brake pedal to the floor slowly. Watch the end of the hose in the fluid for air bubbles. Tighten the bleeder valve and tell the assistant to release the pedal. Repeat this step until no air comes from the end of the rubber hose. Wait five seconds between each repetition.

24

Refill the master cylinder to the Max level with new DOT 3 brake fluid.

25

Repeat steps 11 through 13 on the remaining three wheels in the following order: left front, left rear and right front.

26

Raise the front of the van off the jack stands with a floor jack and remove the jack stands. Lower the van to the ground. Repeat this step on the rear of the van.

27

Repeat steps 1 through 7 to bleed the ABS and TBS modules. Tighten the TBS module-to-bracket bolt with a ratchet and socket.

28

Apply normal braking pressure to the brake pedal. If the brake pedal feels soft or spongy, proceed to the next step. In the pedal feels normal, proceed to step 19.

29

Start the engine and allow it to run for at least 10 seconds, do not move the vehicle or press the brake pedal. Shut the engine off. Repeat this step five times to dislodge any trapped air in the brake system, then repeat steps 10 through 17.

30

Take all old brake fluid to a used automotive fluid recycler for disposal.