964rh

Hi

Going to have a go at refreshing the brake fluid in my C4.

Currently it uses castrol SRF, going to stick with this as the car mainly gets track use.

But, the fluid I'm using at the minute is only 12 months old and the colour of the old fluid is about the same as the new stuff so how will I know when all the old fluid has been shifted?

I don't really want to waste any of the new fluid as it's not the cheapest stuff in the world!!!

Any idea's?

Rob

Rocket Rob

Its not a silly question. Its my experience that when you bleed brake fluid, the old fluid is typically dirty or cloudy as compared to the new fluid. I keep bleeding until I see clear fluid. You just have to use your best judgment.

Good luck

newsboy

You could use ATE super Blue, then you would see the color change. I believe for the C-4, a little under a quart would flush the system. Remember to clamp the reservoir overflow tube, and bleed the clutch slave at the same time.

dfinnegan

From the Shop Manuals:

Change volume for each wheel: approx. 250 cc. Bleed on both bleeder valves of each wheel.

Also drain about 50 to 100 cc of brake fluid on the bleeder valve of the clutch slave cylinder.

elbeee964

Hmmm...
I was faced with something similar when changing my brake lines. And I had just the one can of ATE gold.

1) Obviously withdraw (kitchen baster) as much from the reservoir as possible.

I was using the positive pressure bleed method.

2) Bought a couple bottles of the best brake fluid I could find at Walmart (Dot 4 Valvoline synthetic, I think it was -- $5-$6). Refilled & bled the system w/ them. (Included the clutch while I was back at the left rear wheel. [that little ****e!])

Figured that filled and 'dried' the system.

3) Kitchen baster/empty the reservoir. Then bled the car again w/ the contents of the ATE can -- nothing left over in the can.

Admittedly, that's way over the top, cost me my time & an extra $6. But that system is plenty 'dry', now.

AB-Oz

I've done the brake fluid in my C4 using the positive pressure method, suing fresh off the shelf fluid.

I do my motorcycle brakes and clutch every 12 months.

With something important as brakes, just dispose of your 12month old fluid environmentally and go and get some new stuff.

f@tboy

On my C2 I used ATE blue, so it was very easy to see when the job was done. It took about 750cc, including both sides of the front callipers, and the clutch. I emptied the master cylinder first.

elbeee964

F@tboy, did the blue ATE stain your reservoir plastic?

f@tboy

Not sure, it's only been in there about 6 weeks. I'll have a proper look later on and let you know.

elbeee964

I ask, cuz that occurred on my '85 carrera.

PorscheZen

I would be cautious about changing SRF for ATE Blue (SRF is Synthetic, with higher BP than ATE - it's also been said that ATE is old technology - about 15 years old)
If you don't want to pay for SRF, Motul RBF 600 is getting rave reviews for tracking and has a higher BP than ATE. It's also synthetic. I changed mine from ATE Blue this year to Motul and I really like it.
As a matter of fact, for some reason I'm getting smoother shifting as well.

For track use, it's recommended to flush the system at the beginning of every DE season and bled after each event. It's not the color that is of concern but the possibility that there's moisture accumulated in the lines as well as over-heated brake fluid.

f@tboy

Looks fine, but as I said it's not long in there. How long did yours take to stain?

elbeee964

I noticed after a year, year and a half.
Then, it was damned noticable -- as in, made it difficult to tell fluid color/quality/quantity when I switched back to straw-colored fluid.
Made mental branding iron on my brain never to use blue, again. But that's just me. YMMV.

Optimists perspective: Perhaps the 964 reservoir plastic isn't the same as an '85's reservoir?

Anyone out there have 964 reservoir staining w/ ATE blue?

DWS964

On my C4, I use about 1.5 liters total (ATE Blue in the last flush/bleed), following Adrian's procedure for the PDAS/ABS accumulator, solenoid, differential locks*, all four calipers, and the clutch slave. The Blue was only in the system for 2 months prior to my recent service work, and the resevoir seems to have been stained a bit. Now have a fresh supply of Ate Gold in the system.

*(using a "manual" method for bleeding the PDAS differential locks, rather than a Hammer)

Flushing the brake fluid on the Porsche for safety and preventative maintenance reasons has been a real eye opener for me. All my other cars are now getting their dose of fresh fluid.

Chris Galtress

DWS964,

Could you please elaborate on how you bleed your diff locks without the Hammer. Mine need to be bleed. I've seen posts around using the manual lock switch on the console but that seems impractical. I've though about possibly trying to open them "manually" by applying voltage across them but have not investigated it enough to know if this is truly feasible. Any ideas would be appreciated.

Thanks!!

Chris