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.
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?
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.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.
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.
Good point... You are right.If there were one-way valves your brakes would never disengage
Usually there are seals that prevent you from doing that easily.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.
Usually there are seals that prevent you from doing that easily.
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.
Yeah. And older vehicles sometimes don’t have seals.Aha! Often lacking on simpler vehicles - such as motorcycles.