c3corvette77

What's the best way to clean out the brake system to completely change the fluid? A couple. Years ago I had a mechanic chahge a brake line that I couldn't get loose without rounding it off and he "upgraded" me to DOT5 fluid. Pedal feel is terrible and no, there's no air in the system. I don't want this to turn into extolling the virtues of DOT5 fluid over anything else, just want to know the best way to clean out the system so I can go back to petrolium based fluid.

79L48

I also upgraded to DOT5 and was unhappy and went back to DOT3. Concurrent with replacing my master cylinder, I simply bled the system completely until DOT3 fluid was coming out clean from all the bleeders while filling the master as I went. It took awhile.
There is something called a motive bleeder that introduces pressure into the equation and is effective at replacing all the fluid in the system in short order.

JimT

Start bleeding at the passenger rear until you see new fluid, then to the driver rear, then passenger front, then driver front. All old fluid will be purged.

LB66383

Use a turkey baster or an eyedropper to remove all of the old fluid from the master cylinder reservoir, then fill it with the new fluid before you start bleeding.

vette427-sbc

If you have no air in the system, definitely do not introduce air back into it. We all know how hard it is to get all of the air out of these brake systems.
I recently flushed my brakes out with great results.
Open one caliper at a time and let fluid run out (preferably with a hose attatched to the bleeder screw so it doesnt get all over the place). Keep an eye on the master cylinder and add new fluid when it runs low, NOT out. Repeat until new fluid comes out of the bleeder, then close it up and move to the next wheel.
I used blue colored fluid, so it was easy to see when all of the old fluid was cleared out.
Took me about 20 minutes of sitting on my *** watching brake fluid coming out of a hose, and filling up a master cylinder. Very easy

c3corvette77

If you have the new style rear calipers with 2 bleeders do you open both bleeders together? With this gravity method you just leave the cap off the master cylinder and let it push out the bleeders?

MelWff

Open the outside one first, close when finished, then the inside. leave the cap off the master.

rugerm44

It's inside bleeder first then the outside bleeder on the rear calibers.

gkull

I'm a little more **** about cleaning the system out. At work I had to flush out the brakes on a car that had been sitting for many years. I purged the lines with laquer thinner. Then I disconnected the lines off the master cylinder and each caliper. I used air to blow dry out all the lines. brake fluid gets trapped in each calipers pistons. So I removed every caliper and compressed the pistons to pump the fluid out. I pumped some thinner through each one and blew them out with low pressure air. High pressure air will pop the pistons out.


I put everything back together and pumped through 600 degree AP fluid. Doing the normal bleed proceedure

Gale Banks 80'

Denatured Alcohol is what I use when switching from old to new. How ever I doub't that You can tell the Feel between one Dot and another. For the most part liquids can not be compressed so the only time it could feel diffrent is when they have been heated to very hot conditions when the viscosity might change. Like Road Racing on a Track. How Old are the Rubber Brake Lines? How much Run Out do the Rotors have? How do You know You have all the Air Out?