Brake fluid flush
 

I would like to flush my brake fluid in my 95 blazer 4x4 as it is old and black.What is the best way to flush and replace the brake fluid?It has the 4-wheel abs system,is it bleeded the same way as a non abs system? What brake fluid to use d.o.t. 3,4,5,name brand or no name?


Thanks

Take a cheap turkey baster and suck all the old fluid out of the master cylinder and then fill with new fluid. You can then bleed each wheel until you have clear fluid. this will take a quart or so. Use about a foot of small clear plastic hose pushed onto the end of the bleed screw. You can direct the fluid into a catch can and also you can see when the fluid is clear. This will not flush the ABS pump. You need an appropriate scan tool if you want to do this. DOT 3 is fine and you can use DOT 4 if you want. It just has a higher boiling point than DOT 3. Do not use DOT 5 (silicone).:icon_wink:

It is good maintenance to do this every 3 years or so.

brake fluid flush
 

Thanks Terry

If you just want to drain and refill that is fine. But if you want to flush, I would drain the old fluid ie; gravity bleed. Once you have it drained use denatured alcohol to flush the rest of old fluid out. Let the system dry out by leaving it open. I would recomend replacing hoses at this time. After you have gone this far use Dot 5 Silicone brake fluid. It does not absorb moisture like conventional brake fluid. This is a big job and very time consuming.

For what it is worth I uset to wonder why they did not use DOT 5 in normal vehicles since it does not absorb moisture which is bad for the system. They use it in race cars as it has a higher boiling point. Race cars usually get their brake fluid changed often so moisture usually is not an issue.

The reason DOT 5 is not good for street vehicles is that when moisture does enter the system and it will, the fluid will not absorb it so the moisture stays concentrated and will boil causing a mushy pedal and no pedal in extreme cases. Since DOT 3 & 4 do absorb moisture the moisture is dispursed through the fluid so it will not boil unless there is a large amount of moisture.