1942 - 1947 Chevrolet Shop Manual



	*5-3*

	Unscrew bleeder valve in wheel cylinder 1/2 to 3/4 turn. Depress the foot pedal slowly by hand, allowing it to return slowly. Continuing this pumping action	Hydraulic Brake Fluid Super No. 9. This brake fluid is satisfactory for any atmospheric temperature, hot or cold, that may be encountered in car and truck operation anywhere. A good brake fluid must have a high boiling point to prevent evaporation and tendency to vapor lock and must also remain fluid at low temperatures. Other types of fluid are composed of ethyl alcohol and castor oil: cellosolve and castor oil; alcohol, water, and glucose, with some chromate added to retard corrosion; mineral oil; anti-freeze alcohols, with no castor oil added. The first fluid in this group makes use of ethyl alcohol which has a lower boiling point than diace-tone alcohol, causing it to vaporize more rapidly and increasing the tendency to produce vapor lock in the lines. The cellosolve that is used in the second type of fluid has a rather severe action on the rubber parts in the hydraulic system and should not be used for this reason. The action of the water and glucose used in the third type hardly requires any explanation. The


	Fig. 4—Filling Main Cylinder Reservoir forces the fluid through the lines and out at the bleeder drain, carrying with it any air in the system. When bubbles cease to appear at the end of the bleeder drain hose in the jar and the stream is a solid fluid mass, tighten the bleeder valve and remove the drain hose. Replace and tighten the screw at the end of the bleeder valve. After bleeding operation has been completed at all wheels, fill the main cylinder reservoir approximately full, and replace the filler plug. NOTE—Fluid withdrawn in the bleeding operation should not be used again. HYDRAULIC BRAKE FLUID There are several general classifications of hydraulic brake fluids being sold throughout the industry. However, for the protection of Chevrolet owners we highly recommend the use of G.M.
		Fig. 5—Bleeding Brake System at Wheel Cylinder water, of course, will rust and corrode the metal parts of the system: the glucose has no lubricating qualities whatever and forms a sticky mass when exposed to air. As a slight amount of fluid seeps