Brake fluid flush (NOT bleed)

[glenhendry]

Hi folks, my brakes work just fine, but I do not know how old the fluid in it is (I havent changed it in my 20kkm). I wish to flush new fluid into the system but I also wish to avoid the bleeding process by not introducing air into the system.

If I bleed each corner one at a time (and then the first corner again) wont I be able to replace the vast majority of the fluid and flush out the system without introducing air and necessitating an actual bleed process?

I saw on a different thread that a re-bleed should be done every 12 months! This defies my rudimentary logic involving hydraulic brake systems. There is either air or not in the closed system. I just want newer, cleaner, moisture-less fluid in the system for peace of mind.

I appreciate any input wiser folks can provide. :p

[p38oncoils]

Hi folks, my brakes work just fine, but I do not know how old the fluid in it is (I havent changed it in my 20kkm). I wish to flush new fluid into the system but I also wish to avoid the bleeding process by not introducing air into the system.

If I bleed each corner one at a time (and then the first corner again) wont I be able to replace the vast majority of the fluid and flush out the system without introducing air and necessitating an actual bleed process?

I saw on a different thread that a re-bleed should be done every 12 months! This defies my rudimentary logic involving hydraulic brake systems. There is either air or not in the closed system. I just want newer, cleaner, moisture-less fluid in the system for peace of mind.

I appreciate any input wiser folks can provide. :p


Hi glenhendry. I replaced the brake fluid in my p38 recently and did it exactly as you suggest doing it. What I did was to drain/bleed the majority of the old fluid out of the reservoir before filling it up with new fluid and then did a full bleed with the new fluid. I also bled the two bleed nipples on the side of the master cylinder. As long as you make sure that the reservoir doesn't run out of fluid you shouldn't have any issues.

[Blknight.aus]

a brake fluid flush should be done every 24 months in dry conditions and 12 months in humid environments. (12 months for Australia)

the brake system is not sealed its open to atmosphere at the top. Brake fluid is hygroscopic and pulls moisture out of the air quite easily as well as degrading over time with use. The water laden brake fluid is also denser than the clean stuff so will work its way down to the low points in the system and cause problems.

[goingbush]

Just curious,
has anyone done the bleed / flush using the abs pump via their nanocom.

[PaulP38a]

Just curious,
has anyone done the bleed / flush using the abs pump via their nanocom.

Unless I am misinformed, BBS have not yet released the P38 module for the Nanocom.

If they have, I'll be just a bit p****d off as they sent me the special cable and told me I'd be on the beta test programme ;)

Afraid we P38 owners still have to bleed the old fashioned way...

Cheers, Paul.

[123rover50]

I was going to do the same by changing the colour of the fluid. Swapping red for clear etc and bleeding till the new colour comes through.
Is that feasible or dont they do different colours any more?
Didiman

[Blknight.aus]

yeah they do problem is mostly they no longer make brakefluid in the bottles with the clear strip down the side so you can see the colour of the fluid.

IVe seen it in red, green, blue, yellow and an off clear kind of yellow. the green ,off clear and blue are the most common.

[poleonpom]

Anybody got any views/experience with silicone brake fluid alternatives? Apparently they are non-hydroscopic.

[rick130]

Anybody got any views/experience with silicone brake fluid alternatives? Apparently they are non-hydroscopic.


Compressible.

I refuse to use it for that reason, no one in motorsport uses it for that reason and it can't be used on an ABS system for that reason.

Stick to good old fashioned glycol-ether based fluid.

[Hoges]

Anybody got any views/experience with silicone brake fluid alternatives? Apparently they are non-hydroscopic.

That's a good reason not to use it as the water separates out and causes problems... you can get superheated water droplets in the system from heavy braking ..BANG! the hygroscopic nature of glycol-ethers allows the water to stay in solution meaning that while the boiling point of the overall mix is lower the water content doesn't 'superheat'...

[RR P38]

If you draw all the fluid out of the reservoir with a clean syringe or oil sucker you can be sure to get a nice clean charge of oil into the system.
Make sure you use something that is spotless.
I use a large surgical syringe.
That mesh screen under the filler cap can be a bugger to get out though.
Grab your self a Repco one man bleed kit ($10 ish) or use some clear hose off the nipples it makes it real easy to see the clean fluid come through.
I put the Modulator kit through mine this time last year.
It was suprising how clean the system was inside, but i have done a flush every 2 years for the last 12 years.
Cant say that i have ever had a problem with bleeding the system.

[adm333]

You should stick to plan A, and I will come over and help you bleed / flush using the proper procedure. It's not too difficult with 2 people.

I have done it many times ( well about 5)

Brakes always feel better afterwards.

Your theory will not flush out all of the chambers of the brake modulator. There are 3 bleed valves on it alone.

One night next week is fine by me

Dave

[glenhendry]

You should stick to plan A, and I will come over and help you bleed / flush using the proper procedure. It's not too difficult with 2 people. I have done it many times ( well about 5). Brakes always feel better afterwards.

Your theory will not flush out all of the chambers of the brake modulator. There are 3 bleed valves on it alone. One night next week is fine by me
Dave

That is awesome. Thanks Dave. I am very keen. I bought 4 litres of DOT4 last night (ouch) and an easy bleeder, and so how does Tue night sound?

Hoges is a local, maybe he could come and chat and sledge us during the process if he isn't busy. If Tue night is good for you, I'll send a note to the local Bris crew and see if we want to get a pic of Brisbane lineup of P38s. Even though mine is badly in need of a cut and polish. :eek:

[Blknight.aus]

that many p38's in one place?

want me to turn up just in case...

carton per fix.... :)

[glenhendry]

Last night adm333 came around and we bled my 2000 4.6 from 8pm till 11pm. The entire process took two hours once we finished stuffing around and chatting. A formal huge thanks to Dave for spending his precious time to help me out. It all went smoothly and I was feeling pretty happy driving in this morning.

Interestingly I was a little dissapointed that I didnt notice much difference in the brake pedal today. My system must have been fairly free of trapped air; certainly none was released that I saw with the clear tubing. The fluid that came out definitely looked awful though, and I am glad to be rid of it.

Since we didnt let any air enter the system, by continuously topping up the reservoir throughout the procedure, the entire bleeding and flushing process used less than 2 litres of DOT4. And to be honest, we definitely over did it on every screw and every corner. On one (rear) corner, the fluid came out green when the others were all dark honey, so that corner must have been skipped last time it was bled!?

Getting to the uppermost and rearmost bleed screw on the master cylinder was a bit tricky for big hands, as the firewall insulation is thick behind and above it and almost covers it like a blanket, it was pretty much a two person job to get that one. Dave was much better at it than me.

Essential tools:
- 11mm ring/open end spanner
- a Rangey on high EAS mode (and a door or tailgate cracked so it wont level)
- easy brake bleed tube with plastic locking plate (cheap from auto store)
- a sympathetic friend who has done it before
- a torch to monitor the reservoir level
- a few rags
- follow the instructions, they aren't that tricky