SECTION IV. BLEEDING BRAKE SYSTEMS

TB 9-2300-426-20

Use the funnel in the No. 1 Common shop set to

add fluid. This works fine on the 5-ton trucks but the 2

1/2-ton trucks have a crossmember that is in the way.

Use a 6-inch piece of heater hose on the funnel's spout

as an extension to reach the master cylinder.

Clean the funnel and extension before you use

them again. Oily funnels attract dust and dirt that will

contaminate the brake fluid. It doesn't take much dirt

to damage brake systems.

9. Wipe off the fluid bottle cap before you screw it back on. Also, be careful where you lay the master cylinder cap.

Always wipe it off.

10. A few minutes of prevention can save hundreds of dollars and several manhours of repair time.

SECTION IV. BLEEDING BRAKE SYSTEMS

1. The easiest way to bleed brake systems is with a filler/ bleeder, NSN 4910-00-273-3658. It's in the No. 1 and No. 2

Common shop sets, and the instructions on how to use it are in the vehicle's -20 technical manual.

2. If you don't have a filler/bleeder, you can still bleed the hydraulic lines with the help of an assistant, a long piece of

clear plastic tubing, NSN 4720-00-964-1433, and a clear glass or plastic container. The procedure is as follows:

NOTE

Use only clean silicone brake fluid, NSN 9150-01-102-9455.

a. Put about an inch of clean brake fluid in the container.

b. Fit the tubing over the bleeder valve on the wheel farthest from the master cylinder, usually the right rear

wheel.

Run the loose end of the tubing down inside the jar into the fluid.

c. Make sure the master cylinder is full of fresh, clean fluid and the cap is on tight before you bleed each line.

Refill the master cylinder after you bleed each line. Check the reservoir periodically while bleeding. If it runs low, air

can get sucked into the line and then it has to be bled again.

d. Have the assistant pump the brake pedal three times and then hold the pedal down. This will keep the fluid

coming while you bleed.