Okay, so it isn’t actually blood that you bleed, but what is it? Now I know there are at least two schools of thought: 1. silicone and 2. non-silicone. I’m strictly for non-silicone. Sure I have a little more work to do but let’s face the WW2 jeep’s brakes system is open to the atmosphere. Either choice is going to end up contaminated. Well…maybe silicone has an advantage if you never actually drive your jeep! As I said I’m strictly non-silicone, maybe that is old school but really bleeding the brakes is pretty simple.
The hydraulic brake system must be bled whenever a fluid line has been disconnected or air gets into the system. A leak in the system may sometimes be evidenced through the presence of a spongy brake pedal. Air trapped in the system is compressible and does not permit pressure applied to the brake pedal to be transmitted solidly through to the brakes. The system must be absolutely free from air at all times. When bleeding the brakes it is advisable that the longest fluid line from the master cylinder be bled first. The proper sequence of bleeding is right rear; right front; left rear; left front. During the bleeding operation the master cylinder must be kept at least 3/4 full of hydraulic brake fluid.
To bleed the brakes first carefully clean all dirt from around the master cylinder filler plug. Remove filler plug and fill master cylinder to the lower edge of filler neck. Clean off all bleeder connections at all four wheel cylinders. Attach bleeder hose and fixture to right rear wheel cylinder bleeder screw and place end of tube in a glass jar, end submerged in fluid. Open the bleeder valve 12 to 3/4 of a turn. See figure above.
Depress the foot pedal by hand, allowing it to return very slowly. Continue this pumping action to force the fluid through the line and out the bleeder hose which carries with it any air in the system. When bubbles cease to appear at the end of the bleeder hose, tighten the bleeder valve and remove the hose.
After the bleeding operation has been completed at all four wheels, fill the master cylinder reservoir and replace the filler plug. It is not advisable to re-use the fluid which has been removed from the lines through the bleeding process.
If you’re old school or a rookie…or, maybe just want to know how we did back during the war years, you should check out Automotive Trouble Shooting for WW2 Wheeled Vehicles: Volume 1 and Automotive Trouble Shooting For WW2 Wheeled Vehicles, Volume 2