The most important use for the bleeder valve is to remove air from the braking system. As air rises and will not flush out of a bleeder mounted low on the brake the bleeder needs to be at the top.
Disc brakes at the top of the caliper Drum brakes at the top of the wheel cylinder
same as a car, take the caliper off, and leave bleeder to the top, build pressure, hold, open bleeder, repeat.
The bleeder valve is a 8mm bolt for the rears located on top of the drum or on the caliper itself if you have disk rear brakes. For the front, a 10mm bolt is located on the caliper itself. PB blaster should be used to be sure the bleeder valve is not broken
up top of the caliper
Remove the wheel, the bleeder screws are on the inside on top of the caliper.
located on each brake caliper/wheel cylinder for drum brakes. have an assistant pump brake pedal several times then hold down. open bleeder valve. repeat on each wheel until only fluid comes out. top off master cylinder as required. I suggest using line wrench on bleeder screws.
That's the brake fluid bleeder and it should be on top of the caliper. If it is on the bottom you have the left and right caliper mixed up.
on the top or back of the caliper
There should be no need to bleed the brakes after replacing the rear (or front) brake pads. Make sure you place a rag around the top of the fluid reservoir to catch any excess as you press the pistons back into the caliper body though. If the brake pedal has gone spongy after pad replacement this suggests that the piston seals have failed or the caliper cylinder facess have corroded. On mine the bleed nipples are on the caliper body.
The rear brakes on most E350 vans are disc brake set-up....they are replaced just as the front pads are....remove the rear wheels....then open the bleeder valve on the rear caliper (one at a time)....then use a large screw driver and insert it through the oblong hole in the top of the caliper....try and grab the front of the rotor with the tip of the screw driver and slowly pry the caliper toward you...this just eliminates the need to use a c-clamp to press the caliper piston back into the caliper....remove the caliper bolts and lift the caliper from the caliper bracket.....replace the old pads and replace the caliper...if the caliper piston is still not pressed in far enough, use a c-clamp to press the piston the rest of the way in...once the piston is pressed all he way in tighten the bleeder valve (opening the bleeder valve eliminates the chance of pushing trash into the ABS proportioning valve and triggering the ABS light)....replace the caliper bolts...replace the wheel...and then move on to the other side....remember when both sides are done to pump up the brakes (otherwise the pedal will travel to the floor and no brakes)....If your van has rear drum brakes it is a bit more difficult but not bad....hope this helps. Randy Griner ASE master Technician Blue Oval Certified Master Technician
Disc brakes? Start at the longer (Right front) Make sure master cylinder is full open bleeder screw at top of the caliper fluid should start to flow (gravity) When fluid is flowing have assistant step on brake pedal approx. 2/3 of travel and hold Tighten bleeder screw Repeat at left front
Make sure master cylinder is full Start at right front wheel Open bleeder screw at top of caliper Fluid should start to leak out (gravity) When fluid runs out have assistant step on brake pedal and hold Close bleeder screw Move to next wheel