I have a 1996 k-1500 Chevy 4×4. My rear wheel cylinder went out causing master cylinder to go dry. i replaced the master which i bench bled, rear wheel cylinder, shoes, drums, and hardware on both rears. I have tried to use a vacuum pump to bleed the rear brakes. no fluid came through. tried both pulling a vacuum and then opening the bleeder and closed before lost vacuum and then repeat the process and tried opening the bleeder and pulling continuous vacuum neither method ever produced any fluid. I also tried to just let it gravity bleed no luck there either. Bought a scanner that claimed it could auto-bleed anti-lock brakes on most vehicles sadly my truck is not supported by that scanner. How do I get the rear brakes to bleed?
BRAKE SYSTEM BLEED
The braking system can be bled manually or with pressure bleeding equipment. If bleeding manually, check fluid level frequently.
Brake fluid should never be reused. Before driving the vehicle, check brake operation to ensure a firm pedal has been obtained.
Brake fluid will damage electrical connections and painted surfaces. Use shop cloths, suitable containers, and fender covers to prevent brake fluid from contacting these areas. Always seal and wipe off brake fluid containers to prevent spills.
MANUAL BLEEDING
C/K, G, M/L, P & S/T Series
- If vehicle is equipped with a vacuum or hydraulic booster, relieve system by applying brakes several times with engine off.
- Fill master cylinder reservoir with DOT 3 brake fluid. Maintain full level during bleeding procedures.
- If master cylinder is replaced or suspected to have air in the bore, bleed it before calipers.
a. Disconnect forward brake pipe connection at master cylinder and allow brake fluid to flow from connector port, then reconnect pipe but do not tighten.
b. Slowly apply brake pedal to allow air to bleed from loose fitting, then tighten fitting before releasing brake pedal.
c. Wait 15 seconds, then repeat sequence, including 15 second wait, until all air has been purged from bore.
d. After all air has been removed from forward pipe, repeat procedure for rear pipe. - If the vehicle is equipped with four wheel anti-lock brakes (4WAL), the Brake Pressure Modular Valve (BPMV) may need to be bled. If the BPMV has been replaced or is suspected of having air trapped inside, bleed system as outlined in “Anti-Lock Brakes” .
- Bleed each wheel in the following sequence:
a. Right rear.
b. Left rear.
c. Right front.
d. Left front. - Attach a suitable hose to wheel caliper valve and immerse opposite end of hose into a suitable clean container partially filled with clean brake fluid.
- Slowly apply brake pedal one time and hold, loosen the bleeder valve to purge air from caliper, then tighten bleeder valve and release pedal.
- Wait 15 seconds, then repeat sequence, including 15 second wait, until all air is purged from caliper.
- Repeat bleeding sequence at each wheel until system is bled.
- Check brake pedal for “sponginess” and brake warning lamp for an indication of unbalanced pressure. Repeat bleeding procedure to correct either of these conditions.
PRESSURE BLEEDING
A diaphragm type pressure bleeder must be used. It must have a rubber diaphragm between the air supply and the brake fluid to prevent air, moisture, oil, and other contaminants from entering the hydraulic system. Also, adapters are needed depending on the type of master cylinder reservoir used on the vehicle:
Brake Bleeder Adapter (Plastic Reservoir) tool No. J 29567, or equivalent.
Brake Bleeder Adapter (Cast Iron Reservoir) tool No. J 23518-01, or equivalent.
C/K, G & M/L Series
- Fill the pressure tank at least 2/3 full of brake fluid. Bleeder must be bled each time fluid is added.
- Charge pressure bleeder to 20-25 psi.
- Use tool No. J 39177, or equivalent, to depress and hold valve stem on combination valve.
- Install master cylinder adapter tool required for type of reservoir, then install bleeder hose to adapter
- Bleed each wheel in the following sequence:
a. Right rear.
b. Left rear.
c. Right front.
d. Left front. - Open bleeder tank valve.
- Attach a hose to caliper bleeder valve and immerse the opposite end of the hose into a suitable, clean, container, partially filled with clean brake fluid.
- Open bleeder valve at least 3/4 turn and allow fluid to flow until no air is seen in fluid, then close valve.
- Repeat procedure at each wheel.
- Check brakes for “sponginess.” Repeat bleeding procedure if necessary.
- Remove pressure bleeder, adaptors, and tools, then fill reservoir to proper level.