Premature darkening of new-ish brake fluid

1013 Views 14 Replies 8 Participants Last post by HHGadget, May 22, 2022

Wunderkind

Discussion Starter · May 13, 2022

Hi ya,
In spring of 2021, I bled and replaced the brake fluid with new DOT3 fluid. I think the one I got is labeled as Super DOT3 with higher boiling point than regular DOT3/4. Probably marketing. But it was same priced.

I've since put in ab out 3000km during last year's driving season.

In preparation for the upcoming season, I did my usual checks and noticed the brake reservoir fluid were dark brown! The car is stored in a dry garage all covered up. The cap was tight.
I am surprised at how quick it hydroscopic itself from light Chardonnay colour to dark Amber ale colour. There's no leak AFAIK.

Like to know the cause before performing a full bleed process. Any thoughts?

1 - 15 of 15 Posts

shabby

· #2 · May 13, 2022

Did you bleed the clutch too? If not then it mixed with the clutch fluid.

JohnWR

· #3 · May 13, 2022

shabby said:
Did you bleed the clutch too? If not then it mixed with the clutch fluid.

This is my thought as well. It is pretty much impossible to get all of the fluid out of the system. You will also pick up some color from the system in general.

Wunderkind

Discussion Starter · #4 · May 13, 2022

shabby said:
Did you bleed the clutch too? If not then it mixed with the clutch fluid.

Oh fack! I didn't!!!

I read horror stories with bleeding out clutch fluid and it is hard to remediate. I've done once with my RX8 via a slow gravity drip over a few days. Can the Solstice clutch be done that way?

JohnWR

· #5 · May 13, 2022

Wunderkind said:
Oh fack! I didn't!!!
I read horror stories with bleeding out clutch fluid and it is hard to remediate. I've done once with my RX8 via a slow gravity drip over a few days. Can the Solstice clutch be done that way?

The slave cylinder and hose can only be drained by removing them, which means pulling the transmission, so it isn't surprising that you "overlooked" them.

I removed the line from the clutch master cylinder to the slave cylinder and drained the master along with the sequestered part of the reservoir, then bled the master before replacing the hose. Not perfect, but certainly good enough in my mind.

rob the elder

· #6 · May 13, 2022

I use a power bleeder. Bleed under pressure the clutch line has limited interaction with the rest of the brake system. It is pressurized by the clutch pedal travel but the volume of fluid that mixes from the clutch is relatively small. Discoloration generally is rubber from the hoses or other micro contaminates. It’s the water that causes issues I would not be overly concery

agent008

· #7 · May 13, 2022

JohnWR said:
The slave cylinder and hose can only be drained by removing them

Wouldn't disconnecting one of the slave cylinder lines and shoving it into an empty bottle, pumping the clutch pedal several times and keeping the fluid reservoir full accomplish the bleeding/fluid changing for the clutch circuit?

JohnWR

· #8 · May 13, 2022

agent008 said:
Wouldn't disconnecting one of the slave cylinder lines and shoving it into an empty bottle, pumping the clutch pedal several times and keeping the fluid reservoir full accomplish the bleeding/fluid changing for the clutch circuit?

There is only one line from master to slave and the only accessible connection that I know of is at the master cylinder. Disconnecting it will allow you to flush the master, but nothing really allows for emptying the slave.

As @rob the elder stated though, it isn't that much fluid, and isn't really a concern.

If you are really concerned about the condition of the fluid you can get test strips for contamination due to system damage and a conductivity tester to check for water absorption.

Wunderkind

Discussion Starter · #9 · May 13, 2022

Thanks for everyone's responses. Going to think next steps. In the mean time I'll replace the reservoir fluid every few hundred kms to remove the residual old fluid that might be from the clutch.

agent008

· #10 · May 13, 2022

JohnWR said:
There is only one line from master to slave

Hmmm. I was under the impression that there were 2 connections at the slave, like a return line or something similar. I might be mistaken but remember seeing the slave cylinder / clutch actuator having 2 tubes coming out of it...

WintR

· #11 · May 13, 2022

The only way, short of disassembly, to clear the fluid in the clutch is to pump it with fresh in the reservoir, draw that out and refill, then repeat, until it is acceptably clear. You will never flush it all out, however.

Reactions: 2

Hurricane87

· #12 · May 22, 2022

I just wish my brake fluid would stay in the car long enough to get dark....

HHGadget

· #13 · May 22, 2022

JohnWR said:
This is my thought as well. It is pretty much impossible to get all of the fluid out of the system. You will also pick up some color from the system in general.

Please allow me to add a caveat to this frequent response on the forum to this question if I may…

“It’s pretty much impossible to get all the fluid out of the system —— unless you are willing to drop the transmission and pull the slave cylinder inside it to do so.”

Which, having recently done myself for other reasons, I am here to tell ya would probably not be worth the effort just to change the small amount of fluid in the cylinder and clutch line. It is a relatively small amount of fluid in there.

Reactions: 3

rob the elder

· #14 · May 22, 2022

Good advice

Reactions: 1

HHGadget

· #15 · May 22, 2022

agent008 said:
Hmmm. I was under the impression that there were 2 connections at the slave, like a return line or something similar. I might be mistaken but remember seeing the slave cylinder / clutch actuator having 2 tubes coming out of it...

John is correct. Just the one line.
Trust me when you go to reinstall the tranny that “one” line will be more than enough to deal with.

Reactions: 1

1 - 15 of 15 Posts

This is an older thread, you may not receive a response, and could be reviving an old thread. Please consider creating a new thread.