Bleeding the E21 Brakes

Written by steve kupper

Sunday, 08 March 2009

Use DOT 3 brake fluid. Use only brake fluid that has not been opened. Brake fluid absorbs moisture, moisture boils before brake fluid, boiling water does not stop 2002s. Three pints should be on hand to change out the brake and clutch systems. Three methods discussed.  Gravity 1. Fill the reservoir, open the bleed screws and let the brake fluid leak everywhere overnight. Old fashion way - need a partner or helper. 1. Protect the area around the reservoir, brake fluid removes paint, unpainted metal rusts. 2. Fill the reservoir with fresh brake fluid. 3 Start at the right rear. Get a big bottle with a hose to it. The hose needs to be the size that will fit tightly over the bleeder screw. Here is what I use.  The bottom of the jug should have some fluid in it. Keep the tube submersed in the old fluid to keep air from being sucked back into the system. 4. Put the closed end side of a 8mm or 7mm wrench on the bleeder screw then put the hose over the bleeder screw. 5. Ask your helper to get in the car, pump the brakes slowly five times and on the fifth time hold to the floor. 6. While the brakes are held, quickly release the bleed screw a bit and watch for bubbles. Quickly close (after counting one-thousand one one thousand two) the bleeder screw and tell the helper they can release the brake. Get this sequence absolutely correct. Pump, Hold, Release and close the bleeder screw, then and only then, release the brake pedal. 7. Repeat the process until you do not see any bubbles. Use a good light near your work so you can see the bubbles. 8. Keep checking the level of fluid and top off as needed. 9. Repeat the process on the driver's side rear. 10. Now move to the passenger's side front. Bleed in the same manner in the sequence of Upper, Inner and Outer (UIO) 11. Move to the driver's side and bleed like the passenger's side front. 12. Always checking the level of fluid in the reservoir and topping off as needed. Power Bleeder method. 1. Same as the old fashion method but you need a power bleeder and the helper can go fix dinner. 2. Fill the reservoir. 3. Attach the power bleeder to the reservoir and pump to 10-15 psi. 4. Bleed as old fashion way, (no pumping the brake pedal with the power bleeder) keeping an eye on pressure and fluid in the reservoir. Note: some folks fill the bleeder with fluid, I do not. I guess there is another way but I do not know how to do that. That method uses a vacuum tool like a Mighty Vac Brake fluid is nasty stuff, clean up real good and through away the rags or wash them good before you reuse.

Source: http://www.bmw2002faq.com/content/view/94/32/