Bruce In Philly

2009 C2S 101K miles

I was about due for my 2 year brake fluid change and I did something dumb. I ran out of brake fluid before I finished the job. I had a 1 liter can that I thought I had used only half last time... well I guess I used more than that! What a dope.

Anyway, the reservoir is full of new fluid and I did two wheels but could not finish the last two. I will order another can of the stuff and finish next weekend, but a question:

Does the fluid "circulate"? In other words, the fluid in the lines just kind of push back and forth don't they? So the only mixing of old and new is just what was in the top of the lines at cylinder .... in other words, no big deal... if I wanted to be super picky, I would suck out the new fluid and toss it, pour in some new stuff and drain the last two wheels. Or, just drain the last two wheels and top off. What say?

Comments?

Peace
Bruce in Philly

rbennett

Thats the way it was explained to me a while back, fluid pushes and not circulate.
Did you alternate between blue and red DOT fluid so you know it has left the system?

rherring

As I understand it, the clutch slave fluid in the 997.2 does circulate through the brake reservoir, but the brake fluid does not. I wish the blue fluid was still sold in the US, but it is NLA.

Smitten

After you get through this, be aware that you shouldn't use brake fluid from a previously-opened container. Brake fluid is hygroscopic (attracts water) and this leads to water in the system, and the heat boils it off (changes state) and that gas generation in the brake system causes a soft pedal.

Bruce In Philly

I understand this but don't believe it to be an issue. I had the can open for only a very short period of time, then sealed it up. I can't believe the integrity was compromised to where it is no good anymore. Just my opinion but I am open to being swayed.

Peace
Bruce in Philly

nwGTS

It's cheap. Just buy all new fluid and flush the whole system. Lesson learned.

LexVan

Where do you think all that moisture went from the can's headspace?

lurchphil

Question: While I am changing pad and/or rotors, can I bleed the brakes simultaneously using my Motiv brake bleeder? Would I need to disconnect it each time I move to the next wheel because I will be compressing the caliper pistons? May be a silly question but I'm still learning - I hope...

rbennett

I ordered this Motive product from Pelican Parts about 10 years ago for my 930 and makes flushing a quick one person job.
Requires crimping fluid overflow line and using fresh fluid. I usually just left the unused fluid in the container sealed off and used it later without issues unless I was switching fluid color.

Haven't tried it yet on the 997 but specs say it will work.

http://www.pelicanparts.com/Porsche/...EDR_pg7.htm#75

djantlive

Why not buy locally and finish the job?

mattyf

That's not so dumb. I once flushed my windshield reservoir with brake fluid. That was dumb. In my defense it was dark, I was drunk and the power bleeder fit

Verboden

Since you ask to be swayed, I found two semi authoritative comments on this. The links are:

http://www.stoptech.com/products/str-brake-fluid
http://www.onallcylinders.com/2014/0...e-brake-fluid/

The first is simply an information post from a major manufacturer indicating that their steel cans have a 25% longer shelf life (unopened) than plastic containers.

The second mentions the author contacting fluid suppliers about the unopened shelf lives and getting answers of 2-5 years (or unlimited for one maker).

My conclusion is that if unopened have best by dates then anything opened has a much shorter timeframe.

For me, this does not equate that exposed fluid is now unusable but simply it has some level of water absorption. I would consider how the fluid was stored (temp or environment, dry or rainy climate, and length of time).

I just did this on a brake job. If you are simply bleeding the brakes and not flushing the system then it does not matter. But if you are flushing the system the issue to consider is how the brake fluid mixes. The key thing is that at each wheel flush the line first before replacing parts or moving the pads. Otherwise you can end up pushing old fluid back into the system contaminating the new fluid before you bleed it back out.

Bruce In Philly

Interesting stuff.

Regarding shelf life dates. I am intensely wary of them. In my past, I am aware of a famous, global food company attempting to improve their distribution system, improve discipline on distributors, and sell more product (desires that virtually every large organization have). They did this by simply shortening the shelf life dates on all their products. Worked famously. I say famously as it is a common tactic for virtually any product. What was started as a tool to ensure quality for customers has evolved to be an established technique for improving the bottom line.

Peace
Bruce in Philly

Verboden

Well then there is another option if you like to test things. They make moisture testors, I have no idea how reliable thay are.

https://www.amazon.com/Brake-Fluid-Tester-calibrated-fluids/dp/B005HVG4GQ

I saw some references to test strips, but it looked like they looked beyond moisture.

177mph

Who sells this blue and red fluid? From my understanding- its not available.