No brake pedal

WILLIAM HAMBLIN

MEMBER
1999 CHEVROLET BLAZER
4.3L
V6
4WD
AUTOMATIC
240,000 MILES

I have brake fluid in the reservoir, but brake pedal goes to the floor and when you step on pedal there is an air sound.

Wednesday, August 5th, 2020 AT 8:21 AM

3 Replies

ASEMASTER6371

MECHANIC
52,797 POSTS

Good morning,

Did you check for any leaks at any of the lines?

https://www.2carpros.com/articles/brake-pedal-goes-to-the-floor

It sounds like you need a new master cylinder as it will not build any pressure.

https://www.2carpros.com/articles/how-to-replace-a-brake-master-cylinder

https://www.2carpros.com/articles/how-to-bleed-or-flush-a-car-brake-system

The air sound comes from the booster due to the distance the pedal travels.

The system will have to be bled when you are done. There is an automated bleed for the ABS unit. This requires a scan tool for the procedure.

Roy

Two Person Procedure

Important:
Use the two-person bleed procedure under the following conditions:
Installing a new Electro-Hydraulic Control Unit (EHCU) or new Brake Pressure Modulator Valve(BPMV).
Air is trapped in the valve body
Do not drive the vehicle until the brake pedal feels firm.
Do not reuse brake fluid that is used during bleeding.
Use the vacuum, the pressure and the gravity bleeding procedures only for base brake bleeding.

1. Raise the vehicle in order to access the system bleed screws.
2. Bleed the system at the right rear wheel first.
3. Install a clear hose on the bleed screw.
4. Immerse the opposite end of the hose into a container partially filled with clean DOT 3 brake fluid.
5. Open the bleed screw 1/2 to one full turn.
6. Slowly depress the brake pedal. While the pedal is depressed to its full extent, tighten the bleed screw.
7. Release the brake pedal and wait 10-15 seconds for the master cylinder pistons to return to the home position.
8. Repeat the previous steps for the remaining wheels. The brake fluid which is present at each bleed screw should be clean and free of air.
9. This procedure may use more than a pint of fluid per wheel. Check the master cylinder fluid level every four to six strokes of the brake pedal in order to avoid running the system dry.
10. Press the brake pedal firmly and run the Scan Tool Automated Bleed Procedure. Release the brake pedal between each test.
11. Bleed all four wheels again using Steps 3-9. This will remove the remaining air from the brake system.
12. Evaluate the feel of the brake pedal before attempting to drive the vehicle.
13. Bleed the system as many times as necessary in order to obtain the appropriate feel of the pedal.