This Task Covers:
ZSemitrailer coupled to towing vehicle (manual bleed-
Z Plastic tubing
General mechanic's tool kit
Personnel Required: Two
q Drain pan
Z Pneumatic brake bleeder
a. MANUAL BLEEDING
Use a drain pan to catch any draining brake fluid. Clean up all spills.
Clean bleeder valve (l). Connect plastic tubing (3)
to bleeder valve.
Ensure that end of plastic tubing remains sub-
merged In brake fluid.
Submerge free end of plastic tubing (3) in
approximately 3 in. (7.6 cm) of clean brake fluid.
Use a clean, clear jar (2) or bottle to hold brake
Master cylinder must be kept full during bleed-
ing to prevent air from entering hydraulic brake
Remove filler plug from master cylinder. Fill
master cylinder with brake fluid to within in.
(13 mm) of top.
Open bleeder valve (1) by turning counterclock-
Do not pump brake pedal during step 5.
Have assistant press and hold brake pedal on towing vehicle. Fluid will be forced through tubing to expel air,
which will show as air bubbles in fluid coming out of plastic tubing (3). Continue holding brake pedal until air
bubbles no longer appear. Ensure that plastic tubing remains submerged in brake fluid.