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Brake fluid flush

Discussion in 'Chevy Suburban Forum (GMC Yukon XL)' started by bazar01, Jun 14, 2012.

  1. bazar01

    bazar01 New Member 100 Posts

    How often do you guys change the brake fluid?

    The brake fluid on my burb is getting dark. I plan to suck out the dirty fluid off the reservoir first then fill it up with fresh fluid then bleed manually using the 2-man brake pedal pumping and wheel caliper bleeder opening procedure. First time after 160k miles. Anymore steps i missed out?
  2. Coach24

    Coach24 New Member 1000 Posts 100 Posts

    A brake fluid flush is best done by a machine. This will do a much better job of cleaning all lines and eliminating any contaamination. it is fairly inexpensive at most brake shops
  3. RallySTX

    RallySTX New Member 100 Posts

    Coach is right, but your interval is dictated by use, and quality of fluid. Normally, the fluid only changes color due to high heat, like when the calipers get really hot. Normally when replacing parts, enough fluid is lost and replaced to keep things rolling along well enough. Sometimes however, and sooner or later things happen, and it's time for a complete flush. The biggest problem I ever experienced with brake service, is getting the bleeder valves open. Ofter I have had to replace calipers and rear wheel cylinders due to this issue. I found the using a small drill bit in a pair of pliers to clear out the holes, and wire brushing and spreaying the outsides with PB Blaster or WD40 for three days, twice a day, and using a six point socket, did the trick.
    Brian L.
  4. bazar01

    bazar01 New Member 100 Posts


    I hate shops @#*ing up my ride. I would rather do the work that don't require special tools and equipment. I am only talking about replacing the old fluid and nothing more. The burb has never seen snow or salted roads and I don't anticipate siezed bleeder or stuck calipers. Besides, I plan on involving the wife. Thanks.
  5. bazar01

    bazar01 New Member 100 Posts

    Thanks for the reply.

    Well with 160k miles, I thought it won't hurt to do a flush and besides the fluid is dark. PB blaster is a good idea to soak the bleeders a day before the flush. I have fitting wrenches and small six point wrenches for the bleeder. I don't anticipate siezed or rusted bleeders since the vehicle spent most of it's life in southeast. I already looked at the bleeders and they are clean.

    Will the flush also take care of the old fluid in the ABS pump?
  6. RallySTX

    RallySTX New Member 100 Posts

    I don't know about the ABS pump, all I can say there is once you bleed what you can out of the system manually, fire the truck up and depress the pedal with the rear brake valves open, and see if you get clean or dark fluid. You will have to rebleed them manually after that. Is the pump before the master cylinder or after it? I recommend a vacume pump, you can get at autozone for arround $50. It makes the bleeding job, a one man chore, and reduces spillage to nothing. I have one, and my only complaint is the bottle isn't big enough for my needs. But I just empty it and keep going. Anybody with two hands wouldn't have an issue with that, but as I only have one arm, I'm gonna gripe! I've been the pedal man, and the wrench man so often it aint funny, so I feel your need. Good luck, and please let us know how it went.
    Brian L.
  7. Pikey

    Pikey Moderator Staff Member 1000 Posts 100 Posts

    I have always just done a gravity bleed on my trucks. I just open all the bleeders and keep filling the the reservoir until the fluid comes out clean. No, this does not get out all the contamination like a brake shop would, but it does replace all the fluid. In a jam (hard to get help around here sometimes) I have used the bleeder screws with a check valve. You can pump your brakes and it will shoot fluid out but not let air in. My neighbor does his every year. He uses a cheap vacuum bleeder that he bought at harbor freight. It seems to work well.
  8. bazar01

    bazar01 New Member 100 Posts

    Thanks. That is a good idea. Gravity bleed. The only issue really is letting air in the lines and if I keep the reservoir full, I shouldn't be letting air in, right? Or am I better off getting a bleeder with check valve?
    Do I do the closest caliper first then the farthest last?
  9. Pikey

    Pikey Moderator Staff Member 1000 Posts 100 Posts

    As long as the reservoir is full you will not have to worry about air. I just open all four and let it start running out. The bleeder with the check valve speeds the process, you can force the fluid thru instead of letting it drip out. As far as the order goes, I have no idea what the proper order would be. If you are not bleeding air out I don't think that it should really matter.
  10. tbplus10

    tbplus10 Super Moderator Staff Member Platinum Contributor 1000 Posts 100 Posts

    Harbor freight sells their brake bleeder for $30 it does a great job.
    Motive also sells a real good vacuume bleeder that has a resevoir to fit on top of your existing resevoir so you dont run out of fluid while drawing down, it's designed to be used when doing fluid changes.

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