Break fuild

[e34musician]

Can I just change whatever in the break fuild reservior weekly until it's clean? I just don't want to mess with bleeding if not necessary.

Can I mix dot3 with dot4? What do you guys use? Thanks!

[DaveVoorhis]

Brake fluid doesn't circulate, so if you change the juice in the fluid reservoir you'll wind up with a clean reservoir, but all the stanky old goo will still be riding around in your calipers.

You can add DOT4 where DOT3 is being used, but it's a bad idea to add DOT3 where DOT4 is being used because you'll reduce the fluid boiling point.

[e34musician]

Thanks! I thought the fuild circulate. If not, (just curious) how come the fuild get dirty in the reservior if it doesn't circulate?

Hmmm, if that's the case, I probably need to get dirty again for this. Any suggestion if I have to do it myself without a helper?

Brake fluid doesn't circulate, so if you change the juice in the fluid reservoir you'll wind up with a clean reservoir, but all the stanky old goo will still be riding around in your calipers.

You can add DOT4 where DOT3 is being used, but it's a bad idea to add DOT3 where DOT4 is being used because you'll reduce the fluid boiling point.

[swenpro]

beer is common break fluid... I personally recommend orange juice

[DaveVoorhis]

The dirty appearance is mainly from absorption of airborne moisture, which occurs throughout the system. Also, a contaminant introduced at any point in a fluid will slowly disperse throughout all the fluid. Put a drop of food colouring in a perfectly still jug of water and you'll see.

You can use a one man bleeding kit (see http://www.corral.net/tech/maintenance/brakebleed.html, for example), but I regard brake bleeding and other multiple-bodies-needed jobs as a good excuse to get the bro's around for beer and BBQ, or a way to test if your girlfriend is truly worthy.

[Evan]

great post, dave

[Ross]

The dirt in the resevoir is a result of the fluid that flows back when the brakes are released. Not circulation perse. The fluid is hydrophillic, so the moisture it absorbs from the atmosphere rusts the steel parts in the system. Hence the need to refresh it.
You can gravity bleed your system yourself by removing all you can from the resevoir with a turkey baster, refilling and opening the bleeders one at a time until clear fluid flows. Be careful not to let the resevoir run dry.

[DanDombrowski]

It doesn't circulate, but enough of it goes back and forth when you pump the pedal to make the resivoir look dirty after you fill the resivoir with clear fluid.

I have a motive power bleeder (since I have 0 friends that like to work on cars), and I can bleed the brakes on an E34 in about 20 minutes. Its very easy.

I ususally run the rear of the car up on ramps to get to the back two bleeders, and I can reach the front two without lifting the car IIRC. Screw the cap on the power bleeder to the MC resivoir and pump up to 15 psi. Bleed all 4 calipers and you're done.

[zman-95-540i]

I also use a Motive bleeder. It is definitely worth the money.

[e34musician]

Heard quite a bit of good thing about "Motive Bleeder".

Where can I buy one (Motive Bleeder) from? Does AutoZone carry them?

Break Fluid is the only fluid in my car that have not been changed.