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I've been hearing and reading more and more about the importance of changing brake fluid. Evidently brake fluid absorbs water and can cause problems with the lines and moving parts of the braking system. But, I'm not sure the proper method of changing out the brake fluid and with the ABS, you don't want to do it wrong. Can anyone provide a procedure for changing out the brake fluid? Thanks!
Suck the master cylinder as dry as possible with a turkey baster. Then refill with new fluid. Now start at the right rear wheel. Open the bleeding nipple at the backside of the wheel hub and have somebody else push the brake pedal down to the floor and hold (pressure releases the fluid). Tighten the nipple. Repeat until discharged fluid is clean and clear at this wheel then the others. Just don't let the master cylinder go dry when you are flushing the lines as you don't want to introduce any air into the system.
Brake fluid is a nasty little liquid. Be careful with it and try to avoid any spillage or contact with skin. Have something like a little jar ready to catch the squirts. I've found that by pushing a two-foot long section of vacuum hose onto the nipple (after I've put a boxed-end wrench on the nut portion) enables me to direct the brake fluid into the jar.
Just a tip if you don't have anyone to help you......buy a handheld vacuum pump at wal-mart (not expensive). This way you don't need someone to press the brake pedal, just suck the fluid out with the pump.
I've never done the brakes on my expy, but I've used the vacuum pump many times to bleed the brakes on my motorcycle.
I had a nasty occurance about 10 years years back (with a Mazda B2000) . . . on a day snowboard trip to Snowshoe, WV it was -15 degrees below zero and what moisture had been absorbed in my brake lines froze while the truck sit in the lot awaiting my return . . . for those that don't know, Snowshoe is a 'Montain top resort' meaning that you have to drive down the mountain when leaving . . . well, I load up, get in and start my 5 hr ride home after a great if not bitter cold day on the slopes only to find, as I approach the second sharp turn coming down the mountain, that I no longer have any brakes . . . what a ride!!!
Needless to say I have been a big fan of changing out brake fluid every two years since then!
Also, you don't need help, or additional equipment. The system will gravity drain, it just takes longer. There have been discussions about stroking the master cylinder past it's normal stroke when bleeding using the two person method and damaging the seals. Take that for what it's worth. Suck out the resovior and fill with new fluid. I used a bottle with a clear line attached. It hangs from the caliper, start at the right rear. Open the bleed screw and let drain until clear. Keep the resivoir full. This takes a little longer, but it works. I used the time to do other maintenance... lube job, lube hinges, change air filter, inspect, etc....
Someting that may be more useful is a pressure bleeder like the ones sold by Motive Products (http://www.motiveproducts.com). Of course if you are feeling industrious, you can also make one your self - bear in mind that the following links are for making a pressure bleeder for vehicles other than the Ford Expedition but the sites do illustrate the basic principle):
One suggestion, if you use the 2 person method, put a hose on
the bleeder, and into a container with brake fluid in it already.
By doing this, there will not be any air drawn back into the
system.
A very good point about damaging the seals in the master cylinder. The portion of the cylinder that isn't used regularly can form rust from moisture, and when the petal is pushed beyond the normal travel, the o-rings on the master cylinder piston can be
damaged.