Welcome! Log In Create A New Profile

Boxster S brake flush - can you do it with 1L of new fluid?

Tire Rack: Your performance experts for tires and wheels
Buying through this link, gets PB a donation.

Own a Porsche? Join the Club.
In prep for my trackday, I flushed out the brake fluid in my Boxster S early this week ( it was over due anyways.)

I had trouble getting it done with 1L of fluid, or it's hard to tell when the old fluid transitions to new fluid at the bleeder. Without dye options available, it's hard to judge between almost clear of new to the light amber of old.

I was able to empty 90% of the reservoir at the master cylinder with a vacuum device, and used a motive power bleeder to do the task. I ended up with a lower level then minimum at the reservoir when done, and I topped up the reservoir with fluid from a recently openned bottle.

How much fluid do you think is in the brake lines to the back? the diameter of the tubing is pretty small... 30cc -60cc ( 1-2 fl oz?)
The job, IMHO, takes about 750 mL. I use a self-graduated catch bottle (coke bottle with markets made by magic marker in 50mL increments).

The first caliper i remove 250+ mL from, to accommodate for fluid in the reservoir, master and feed line.

Others I take ~150mL each. Fluid in the lines is pretty small. Watch it travel in your clear tube - and remember that clear tube is likely 4x the internal cross-section of the hard line's.

Grant

Grant gee-lenahan-at-vee-eff-email-dot-net
Thx.

Yeah, I have a Dasani water bottle with a piece of wire taped to the side for a hanger as my catch bottle. Graduations are probably a good idea.


Since I drain most of the old fluid from the reservoir, I'll aim for 150mL from the outer nipple, 50mL from the inner nipple on each caliper. That way I should have enough to do the full brakes with 1 new bottle next time.


Grant gee-lenahan-at-vee-eff-email-dot-net
FWIW, the WSM for the 981 calls for 250 ml per caliper.
They are not equal. The rear calipers are smaller. The first belled drains additional lines and part of the reservoir and master... so if 1 is 250mL, the others are not. Its likely a great simplification. Since i have - long ago -- run it until the fluid goes from "darkish" to "lightish" I'm pretty confident in my measurements, for a 986/7 anyway.

Grant

Grant gee-lenahan-at-vee-eff-email-dot-net
Similar
Boxsterra - 3 months ago
I use the color transition but in my experience the right rear takes about 350 ml, left rear 250 ml, then I use the remainder of the 1L evenly between the two fronts (which don't take much at all).
I typically use about 1.5L, I feel it is better to be thorough than to be tight.
Sorry, only registered users may post in this forum.

Click here to login