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I am changing my master cylinder and booster today. If I want to blow the brake lines out with air do I need to bypass anything I was going to disconnect at the calipers and wheel cylinders. Do I need to disconnect anywhere else. I really don't want any of the old fluid in there. One more question. As far as I can tell the only difference between DOT 3 and 4 is the temp and the fact they don't mix. Any disadvantage to running DOT 4 fluid? :rotfl: :rotfl:
 

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isn't DOT 4 a silicone based fluid? or maybe that was DOT 5? dude, just use the DOT 3 stuff... anything else is something your system wasn't designed for.
 

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ya, dot 5 is the lilicone stuff. if you just empty the master then fill it with dot 4 (I have even seen different colors) then bleed the brakes till you get nice clean brake fluid out you should be fine.
 

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I wouldn't blow air through the lines unless you disconnect/bypass the proportioning valve. You'd likely get the plunger stuck in one direction or the other.

Personally, I'd go around to each corner (after the master is changed) and open the bleeder screws one at a time starting with the RR and working your way up to the closest screw, the LF. Get some clear tubing to fit over the bleeder screw so you can drain into a container and see the fluid. Just let the system gravity bleed at each corner until you see clear fluid. This way you can do it yourself and it also a pretty reliable way of bleeding the brakes.

You could also crack all the bleeders with the master off and let all the old fluid drain out. You stand a better chance of getting the system air locked this way though, which would require the old pump and hold method if that happens.

You probably know this next part already but i thought I'd throw it out anyways. Whichever method you use, don't let the master run dry and suck air.

Umm I GTG, I think my PC is about to blow up. I try and expound later.....
 
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