Is there a best way to clean out brake lines that have just sat there for a (few) years? Lines were connected after caliper rebuild but not filled with fluid so I guess open to the elements.
I would simply run new fluid through the lines. You may suffer a bit of surface rust on the pistons, but so be it. If the brakes work, have fun driving it. Don't over think the issue. Worst case is that you have to rebuild the calipers, which is not different than what some might recommend now. Maybe flush again in several months once the water vapor has been absorbed by the fluid. Jim S.
Thank you, not thinking certainly is the route with least resistance but inquisitive minds need to know. I think it over so that when I do it and something goes wrong I won't beat myself up. In thinking, I wondered what the effect of little rust build up would have on the master cylinder and are there crevices where this stuff can settle, build up and come loose at the wrong time, like a plaque in an artery. No what i mean?
As a rule, brakes do not fail catastrophically. A little surface rust, over years, will leave sediment ("mud") in the master cylinder and caliper cylinders, but this does not lead to catastrophic failure. A more common failure mode is "swelling" of the internal surface of the soft lines. As these swell from years of brake/water exposure, they can act as a one-way valve, allowing pressure to activate the caliper, but not allowing release of pressure, thereby resulting in dragging brakes, hot rotors, and caliper seal leakage. Jim S.
That's great info Jim, thank you. I am trying to wrestle with the concept. The lines swell resulting in a restricted path way, pressure from the servo will force the fluid through, apply the brakes the keep line somewhat pressurized causing the brakes to drag?
Precisely. The master cylinder provides enough pressure to open the occlusion and pass the pressure on to the caliper. Remember, unlike mammal arteries, brakes require very little flow; primarily pressure. When the pedal is released, there is precious little force applied to the pads to spread them, hence, they stay on the rotor. Pad motion away from the rotor is a passive process. Pressure retained in the soft line distal to the occlusion is sufficient to thwart the pad's attempt to move away. Jim S.
No way of testing right? So I think I will flush out the lines with clean fluid and collect the old stuff at the other end and throw it away. I'll stop when I see only clear fluid coming out. Hopefully that will get rid of any loose stuff. Thanks Jim.
