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Note that you can safely flush about 250ml from the reservoir without getting air if you don't put fluid in the bleeder--more than that doesn't work out well.
I found out the hard way and had to bleed the system after my air flush. Pedal to the floor=bad. The way the reservoir is shaped the level goes down very, very quickly after that 250ml.
Interesting, good insight. I added your comment to the instructions above. I just looked at mine, I think you can use a needle nose plier to remove. Using a brake bleeder, it's best not to have the screens as my theory is it creates micro bubbles.
Hi! I’m about to resurrect this thread by asking if flushing the clutch (manual transmission) is also required on every brake flush. I know both brakes and clutch use the same fluid reservoir. If clutch flush is required, can someone post the procedure for the 991?
I also would like to ask a question re this pressure bleeding. In other (BMW) cars I own, I use the pressure bleeder in conjunction with pumping the brake pedal. That seems to produce a much higher fluid flow out of the caliper. I noticed here that no one does this. In one post on bleeding the 996 that Porsche recommends pumping the brake pedal if a master cylinder or hydraulic unit is replaced, probably to flush any trapped air out faster.
Any real reason not to use the brake pedal during flushing?
You guys think 1.5 liters of fluid is enough for a flush / stainless brake line swap? I like to have extra fluid in the event of an accidental whatever, but at $40 per .5L, not trying to go too overkill. Going to switch to Endless RS-650 fluid and FVD stainless lines.
After decades of doing brake flushes on various cars (starting with a two-man job "back in the day" with one guy pumping the brake pedal while the other guy works the bleed screws/bottle, then upgrading to the Motive Power Bleeder), I just did my brakes this weekend with the Harbor Freight version of the air compressor tool.
TOTALLY AWESOME. Can't believe I waited this long to try it. The Harbor Freight one even comes with a fill bottle and various size adapters so you can place the fill bottle in the brake fluid reservoir and prevent the dreaded empty reservoir/air bubbles from happening. The nozzle for the bottle goes down far enough so it never over-fills the reservoir and only releases fluid as the reservoir drains during the flushing. I plan to mark the bottle before doing it next time so I know exactly how much fluid I'm using on each caliper.
After decades of doing brake flushes on various cars (starting with a two-man job "back in the day" with one guy pumping the brake pedal while the other guy works the bleed screws/bottle, then upgrading to the Motive Power Bleeder), I just did my brakes this weekend with the Harbor Freight version of the air compressor tool.
TOTALLY AWESOME. Can't believe I waited this long to try it. The Harbor Freight one even comes with a fill bottle and various size adapters so you can place the fill bottle in the brake fluid reservoir and prevent the dreaded empty reservoir/air bubbles from happening. The nozzle for the bottle goes down far enough so it never over-fills the reservoir and only releases fluid as the reservoir drains during the flushing. I plan to mark the bottle before doing it next time so I know exactly how much fluid I'm using on each caliper.
Is the correct Harbor Freight Re-Fill bottle you used? Thanks.
I used the same and it got about 90% of the bubbles out. I finished it up with the traditional 3 pumps/bleed procedure a few times and all was well.
Hmmmm.....while the drain tube has lots of bubbles when draining (it's more like half fluid half air), that's because of the way it's creating a vacuum by pushing compressed air through the nozzle of the canister/gun. It concerned me at first, until I realized it wasn't going to look like a traditional flush where you're pushing fluid out (and the drain tube looks almost completely full of liquid). What I did make sure to do was keep pressing the trigger/handle until I had completely closed the bleed screws because if you let off the trigger while the screws are still open you can get air sucked back in to the caliper/lines.
Hmmmm.....while the drain tube has lots of bubbles when draining (it's more like half fluid half air), that's because of the way it's creating a vacuum by pushing compressed air through the nozzle of the canister/gun. It concerned me at first, until I realized it wasn't going to look like a traditional flush where you're pushing fluid out (and the drain tube looks almost completely full of liquid). What I did make sure to do was keep pressing the trigger/handle until I had completely closed the bleed screws because if you let off the trigger while the screws are still open you can get air sucked back in to the caliper/lines.
Makes sense and probably the case-either way its definitely the way to go! I learned something new on the bottle with keeping it submerged in the fluid and having it keep the res. full of fluid-did you just submerge and open the petcock valve once submerged? I ended up not using the bottle and just refilling after every caliper.
Makes sense and probably the case-either way its definitely the way to go! I learned something new on the bottle with keeping it submerged in the fluid and having it keep the res. full of fluid-did you just submerge and open the petcock valve once submerged? I ended up not using the bottle and just refilling after every caliper.
That's basically what I did. First I removed the screen. Others have said they struggled with that, but it's got notches on the side of it. If you just grab an edge with needle-nose pliers and pull up with a little bit of pressure while rotating the screen you'll find the "sweet spot" and it pulls right out. Then I extracted as much (or little depending on how you look at it...lol) old fluid out of the reservoir (the way the reservoir is you really can't empty much of it), filled it to the max fill line with new fluid, then put the bottle in the reservoir and opened the petcock valve. Physics keeps it from overflowing and the actual level is somewhere between min and max (been a long time since I took physics and I'm a business guy so don't ask me the technical physical term....lol). Once I bled all the calipers and removed the fill bottle I topped off the reservoir with just a bit more fluid after putting the screen back in.
I'm about to remove my calipers to replace pads, add Tarett studs, and install Spiegler stainless brake lines.
I was thinking to first drain all the brake fluid so that when I removed the stock lines I wouldn't have a bunch of brake fluid coming out.
Since I will be putting in high temp track fluid I want to be rid of the stock fluid anyway.
Then I started wondering whether I'd ever be able to get all the air out of the system what with antilock brakes and such involved.
Is it OK to drain out all the fluid?
Will I be able to get the air out after closing the system and doing a proper bleed?
04-14-2019, 12:48 PM
