Brake fluid MM 7 service

Discussion in 'Clarity' started by JKroll, Jan 24, 2021.

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  1. JKroll

    JKroll Member

    Dealer or any service shop?
     
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  3. JFon101231

    JFon101231 Active Member

    There is a separate thread discussing the merits of such service if interested. Otherwise, either is more than capable to perform the service or they shouldn't be in business ;)
     
  4. Recoil45

    Recoil45 Active Member

    There is some benefit of actuating the abs system during the process. It’s hard to say if the dealer or independent shop is more likely to do that. Probably a question for them before you decide.


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  5. On the one hand, I’m pretty sure I’ve owned decades-old vehicles that never had their brake fluid changed, to no ill effect.

    On the other hand, I do try to replace the brake fluid on my motorcycles at least every couple of years.

    As an aside, I once had a heck of a time bleeding the brakes the conventional way on a motorcycle after replacing the brake lines with stainless lines. Eventually sprung for a $30 kit from Harbor Freight that pumps the fluid in “backwards” from the bleeder valve using an air compressor.

    [​IMG]

    Just drain the master cylinder and then pump in fresh fluid from each caliper’s bleeder valve and have someone keep an eye on the master cylinder so it doesn’t overflow, and repeat for each caliper. Easy enough. Thinking about doing it on our Clarity’s third birthday. Just wondering if anyone else has gone this route and if there are any “gotcha’s” to look out for.
     
  6. megreyhair

    megreyhair Active Member

    I replaced my fluid like Fast Eddie B except I kept vacuuming the fluid at the cylinder until fluid was clear and kept filling the reservoir full.
     
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  8. MrFixit

    MrFixit Well-Known Member

    I seems impossible to push fluid backwards through the system like this because the seals / valves are one-way (not to mention the fact that pushing fluid in through the bleeder could very well result in air bubbles since the bleeder threads do not seal).

    The thing I have heard of that seems akin to this is an arrangement using an air compressor to push fluid through from the master cylinder end. You connect the air compressor to a surrogate filler cap on the master and when you open each bleeder valve, the fluid just comes out without having to pump the brakes. Could that be what the Harbor Freight tool was doing?

    Or, you can use a vacuum to pull fluid out of the bleeders (keeping an eye on the level in the master as you describe). I just looked at Harbor Freight, and they do have a tool to pull fluid out of the bleeders like this (using compressed air to create the vacuum instead of a hand pump).
     
    Last edited: Jan 25, 2021
  9. Tom H

    Tom H New Member

    Total $150 at Honda dealer ($20 parts, $130 labor) and it did not take long. It was part of an A017 service at 3 years that I just waited for. First time for the 7 part.
     
  10. I had not thought about one-way valves. My BMW motorcycles have ABS and I had no problem pushing the fluid in at the calipers. Maybe cars are different. A smidgeon of grease seals the bleeder valve well enough. That said, for routine brake fluid replacement I just bleed at the caliper while applying each brake. And at the ABS unit, which has bleeders for both front and rear ABS circuits.

    I have heard of tools that pressurize at the master cylinder, but I suspect each master cylinder design would require its own adapter. If going that route, its just as easy to have my wife pump the brakes as needed as I bleed at each corner.
     
  11. PHEVDave

    PHEVDave Active Member

    If there were one-way valves your brakes would never disengage. Whenever I replace brake pads I always have to push the pistons back in the cylinders so the new pads will fit. This requires that the brake fluid flows back into the master cylinder which it always does.
     
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  13. I had that same thought.

    As an aside, it’s a good idea to clean the exposed portion of the piston before pushing it back into the caliper - it’s easy to damage the caliper’s o-rings otherwise.
     
  14. MrFixit

    MrFixit Well-Known Member

    Good point... You are right.

    Yes, I agree that retracting the pistons demonstrates that pushing fluid back into the master works. There may be some chance of getting air in through the threads. I have heard a suggestion to apply some grease on the base of the bleeder screw to prevent air seepage.
     
    Last edited: Jan 25, 2021
  15. PHEVDave

    PHEVDave Active Member

    Usually there are seals that prevent you from doing that easily.
     
  16. Well, then it’s the seals that can get compromised.

    This is the grit that should be cleaned off before pushing the pistons back into their bores (on a KTM motorcycle):

    [​IMG]
     
    Last edited: Jan 25, 2021
  17. MrFixit

    MrFixit Well-Known Member

    Perhaps @PHEVDave is referring to the accordion rubber dust cover that often blocks access to the piston itself. I hesitate to remove that for fear of damage.
     
  18. Aha! Often lacking on simpler vehicles - such as motorcycles.
     
  19. JKroll

    JKroll Member

    is there anything unique to this car related to fluid change that a carx type shop cannot do well?
     
  20. PHEVDave

    PHEVDave Active Member

    Yeah. And older vehicles sometimes don’t have seals.
     
  21. To answer the OP question, either should work as long as they use DOT 3 fluid. Private shops are usually cheaper.


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