Hydraulic Brake Bleeding: Description: Notes

CHANGES, CAUTIONS, CORRECTIONS 

DISC BRAKE FLUID CAUTION  - Disc brake systems, or combination drum and disc brake systems, use special high temperature brake fluid, usually blue in color. Do not use ordinary fluid on any car with disc brakes, and do not mix ordinary brake fluid with special disc brake fluid.

DISC BRAKE BLEEDING CAUTION  - During bleeding, air tends to cling to caliper walls; therefore, lightly tapping caliper will assist in removal of this air.

1967-70 AMERICAN MOTORS BLEEDING CAUTION  - Before bleeding brakes, disconnect wire from warning light switch and remove nylon switch terminal, spring, and nylon plunger with contact. After bleeding brakes, reassemble switch and connect wire. If warning light switch is triggered, light will stay on. Switch may be reset by removing and replacing plunger as described above. If plunger will not come out easily, apply slight pressure to brake pedal while removing plunger.

1971-73 AMERICAN MOTORS BLEEDING CAUTION  - On disc brakes, disable the metering valve section of combination valve, using suitable tool (J-23774), to hold valve stem at correct length. On drum brakes, remove the pressure differential warning switch terminal and plunger from valve assembly.

1973 CHRYSLER CORP. BLEEDING CAUTION  - If equipped with combination warning, proportioning, metering valve, hold valve open during bleeding, using suitable tool (C-4121). Brake warning light will come on and moderate brake application after bleeding will hydraulically recenter valve and turn light out. Before bleeding, it is recommended that brakes be adjusted until locked (to reduce cup movement and assist bleeding).

1967-73 FORD MOTOR CO. BLEEDING CAUTION  - On disc brakes, hold metering valve stem out with suitable tool (J-22742), while bleeding. After any repair or bleeding, brake warning (pressure differential) switch should be recentralized: Turn ignition to ON or ACC and depress pedal; switch will centralize and light will go out.

1967-70 GENERAL MOTORS BLEEDING CAUTION  - On vehicles with combined drum and disc brakes, the metering valve in the line to front (disc) brakes must be held open by depressing plunger, when using pressure bleeder, except on Cadillac Eldorado. The metering valve on Eldorado has a knob which must be pulled out. After bleeding, release valve. On all vehicles, this procedure is not necessary when bleeding manually.

1977-73 GENERAL MOTORS BLEEDING CAUTION  - If equipped with combination metering, proportioning, warning switch, hold switch open during bleeding, with suitable tool (J-23709). On Cadillac with Track Master, bleed modulator valve first.

WHEEL CYLINDER BLEEDING NOTE  - Dual master cylinder systems will bleed more efficiently if wheel cylinder bleed screw is opened more than one turn. Disc brake calipers will bleed effectively without pressure application. DO NOT let master cylinder run dry.

LOW PEDAL ON FIRST STOP CORRECTION  - If pedal is low or goes almost to floor on first application after vehicle has been sitting for several hours, but comes to normal height on successive applications, the cause may be air in system or incorrect push rod adjustment. To correct, bleed system thoroughly, opening bleed screws more than one turn, then check for master cylinder compensation. See master cylinder articles in this Section. 

Bleed brakes at all four wheels if pedal feels spongy, or lines at master cylinder have been disconnected, or single master cylinder has run dry. If dual master cylinder runs dry, master cylinder will have to be bled separately before bleeding wheel cylinders. If line at only one wheel has been disconnected, then only that wheel needs bleeding. If line is disconnected at any point between master cylinder and wheel cylinders, then all wheels serviced by that line must be bled.