C2 Flush Really A Flush ?

[Peter M.]

Previously on this message board we concluded that because my 1 yr old DOT 4 brake fluid had some cloudiness in the reservoir - most likley it indicated contamination and / or moisture. So now I will purge the system with fresh DOT 4 but --- will either a reservoir thru caliper flush or a reverse caliper thru reservoir flush completely remove all old DOT 4 with new or is a complete caliper and reservoir disassembly required ?

[Jim T.]

Re: C2 Flush Really A Flush ?

I just remove all the old fluid from the master cylinder and fill it with new. Then just bleed each caliper/wheel cylinder until you can see the newer fluid come out.

[Joe L.]

Re: C2 Flush Really A Flush ?

Peter-----

As long as you're replacing with a glycol ester-based brake fluid (which both DOT 3 and DOT 4 are), you don't need to worry about getting "every speck" of the old fluid out. It's VERY unlikely that your system is contaminated to the degree that this sort of flush is necessary. If you can replace 99+% of the fluid in the system by the method that Jim described, you'll be fine.

[Duke W.]

Re: C2 Flush Really A Flush ?

If the brake system has not been regularly flushed, which is typical for most cars, there is probably a lot of debris in the system. You find that you flush the fluid and within a few weeks it appears dirty again.

For this reason I recommend you use cheap DOT 3 fluid and flush when it becomes cloudy again, which could be in a few weeks. Keep this up until it stays clean, and then use DOT 4 is you want, but DOT 3 is adequate. Then if you follow up with a flush every couple of years, it should stay clean with minimum moisture contamination and extend the life of the hydraulic components.

If a car has regular brake fluid flushes it never gets cloudy, but does darken slightly with age.

Duke

[Dan Tewell]

Re: C2 Flush Really A Flush ?

Duke, I was told that the cloudyness or the fluid being dark was an indication that there was moisture present. It seams that all DOT 3 or 4 fluid is crystal clear coming out of a fresh can. If you save this can for a long time after being opened (a year or so) and then look at it, it will be amber or a brownish color. What's your drift on this?

[Duke W.]

Re: C2 Flush Really A Flush ?

Not sure. Some brake fluids are nearly clear and some have a slight amber tint. I've mixed a little water with fresh brake fluid and could not see any difference in color or opacity, but even a tiny amount of petroleum will leave an oil slick.

My theory on the darkening of brake fluid is that tiny rubber particles wear away and are suspended in the fluid, and if it's never changed you end up with that very fine "mud" at the bottom of the reservoir.

I've also observed that fluid tends to darken quicker due to expose to high temps such as the front brake reservoir on a car that's run at the track. I'm not sure if it's caused by more rapid deteriorization of the rubber parts or some chemical reaction due to the heat.

Anyone else have any facts or ideas.

Duke