This checklist from Rusty was an invaluable guide for bleeding brakes. There is only one thing that I would add. If your system is air over hydraulics then the operation needs to be performed with the engine running, not turned off in order to maintain enough air pressure to bleed the lines. I did it the first time with the engine off and after bleeding the first set of brakes there was not enough air pressure to complete the other 2. After starting the engine, the process went much faster and the bleed was more complete (no air bubbles or sputtering,just a nice steady stream ).
quote:
Originally posted by Rusty:
Although two people make easier changing the fluid and bleeding the brakes, one person can do it with the proper tools:
1. Open-end wrench of the proper size to fit the bleeder nipple.
2.a. About 4' of 1/8" or 3/16" (ID) clear vinyl tubing.
2.b. Small nut to thread onto the tubing (as a weight)
3. Plenty of fresh DOT3 brake fluid. For a system the size of a Barth, I plan on having at least three quarts on hand.
4. Rags.
5. Plastic or glass container for bleeding (preferably one that's sealable).
6. Another container for spent fluid.
7. A couple of 1 gallon zip-loc plastic bags.
NOTE: Brake fluid is an excellent paint remover. If your brake cylinder is 'way up inside thew cowl like my Breakaway, also get some large plastic trash bags to protect from spillage!
NOTE: Some bleeder screws DO NOT have a nipple; one person can't flush and bleed the system if this is the case. Check all four corners first.
Here's how I do it solo (the engine is off):
a. To flush, start with the cylinder/caliber closest to the master cylinder (left front). This is the opposite of bleeding, and the reason is we want the fresh fluid to be "upstream" from the old.
b. Place the tubing (nut end) into the discard container (6.)
c. Remove the cover on the master cylinder reservoir. If there's a full rubber gasket (and there should be), remove and place in a zip-loc bag. Replace the cover loosely (we want air to enter the reservoir and vent the system at this stage).
IF THERE ISN'T a gasket, STOP - get a gasket! These gaskets have pucks (expandable, accordion-pleated sections) in them that allow the reservoir to drop as it keeps the master cylinder full while keeping air (and moisture) out of the fluid.
d. Slightly loosen the bleeder nipple.
e. Attach the other end of the tubing to the bleeder nipple, and loosen until fluid flows freely.
When there's a couple of inches of fluid in the container (covering that end of the tubing), you can speed things up by pumping the brake (Press slowly, release quickly). Gravity will prevent the spent fluid from returning to the brake cylinder.
Only empty the reservoir - when it's down, stop pumping the brake. We're going to flush the master cylinder in the next step.
f. Fill the reservoir with fresh fluid (recap the container immediately - brake fluid will absorb moisture).
g.1. Pump the brake pedal some more - check frequently to see that the reservoir doesn't become empty. You will see when the lighter new fluid replaces the darker old fluid in the tubing and the container.
g.2. Allow the reservoir to become nearly empty, then repeat. This will flush the master cylinder.
h. With the bleeder still dribbling, close it.
i. Repeat g.1. next for the right front, then the left rear, then the right rear.
j. Now you're ready to bleed the system. If you've been careful not to allow the reservoir to become empty, there should be very little air entrained. Top off the reservoir.
k. Fill the container (5.) with about 4" of fresh brake fluid; transfer the nut-end of the tubing to this container.
l. Start with the right rear brake; crack the bleeder (only enough to loosen it).
m. Attach the other end of the tubing to the bleeder nipple, and open no more than one turn. Look for bubbles in the tubing; they'll appear first at the topmost section.
n. Pump the brakes (apply slowly, release quickly) several times, then back under the coach and check the tubing for air. If none is seen, close the bleeder.
o. Top off the reservoir and repeat l., m., and n. for the left rear, then the right front, then the left front.
p. When done, press the pedal, checking for firmness. Pump it a few times. The resistance should be felt at the same position from the first to last application. If not, repeat l. though o., in the same order as above, until the position is consistent on each application.
q. When p. is OK, start the engine and again check the position for consistency. It'll likely be lower than before; we're not concerned about the actual position here (except for all-wheel disc brakes), just that the point of max resistance is at the same position, but it should be well off the floor. For disc brakes, the position should be proper, well off the floor.
If the position is low and you have drum brakes, this is a sign that adjustment is in order. Most units will have automatic adjuster, and most can be made to adjust the brakes by backing up and braking sharply. Do that in step s., below.
r. Top off the reservoir, reinstall the gasket with the pucks retracted, and replace the cover.
s. Test drive. Obviously, start slow, and speed up; if they work OK at 20 mph, they'll do fine at 60 mph.
Container 5. can be resealed and used for subsequent bleeding, and that fluid won't reenter the system. The old fluid (container 6.) can be disposed of; some public entities require it to be treated as hazardous waste, but it can be effectively neutralized by mixing with lots of water (now you know why we don't want any moisture in the system), but DON'T pour it into the sewer system...
03/22
9/12
