Changing the brake fluid

[TraceZ]

I picked up a bottle of synthetic brake fluid and a mightyvac.

I know how to bleed the brakes in general, but should I be bleeding the ABS module also? Is it enough to just bleed the 4 calipers until I see fresh fliud, or do I also need to do something special for the ABS module? I want to make sure I get out all the old fluid.


First, I plan to use the mightyvac to suck all the fluid out of the reservior. Then, I'll fill it with new fluid. Then I'll bleed each of the 4 calipers until I see clean fresh fluid. I'm just not sure what to do about the ABS stuff.

[Kevin - Blown 95 TA]

The ABS needs to be bled first. Don't think you should be using synthetic. Use DOT4 instead. Synthetic will seem spongy and it won't absorb moisture which is a function of the regular brake fluid which is what turns it brown. And the absorption of water by the brake fluid gets the water out of the system when you change it.

Oh yeah, and your mighty vac is going to suck a lot of air at the rear bleeders - the air comes between the threads of the bleeder & the caliper, so you can use some teflon tape or thread sealer on there to make the vacuum pump work a little better.

[dochidalgo]

The ABS module has two screws located front of the module facing the CAI hard plastic tube (well in case of the K&N); if it is so in your car, like mine, you'll have to remove the plastic tube and you will be able to access the two bleeding screws of the ABS module. Bleed the lower one first. Remember to bleed the calipers in this order: Rear passenger's, front driver's,rear driver's, front passenger's.
The BMW's car brake fluid DOT 4 is the best you can get, because the boiling temp they can manage. No too pricey over the DOT 4 brands. Some BMW dealer in your area can sell you the brake fluid.

Regards
Dochidalgo

[MN6WS6]

What difference does it make if you bleed it at the ABS module first or not? You're still pulling fluid through the module from the reservoir, so I don't see what the big deal is. Not being a butt, just asking a logical question. I know that when we do a brake flush at work, they pull it from all 4 calipers until it's clear, which usually ends up taking at least 1 bottle of DOT4 to do.

[TraceZ]

Thanks for the info everyone. I'll return this Valvoline Synpower stuff and go get the DOT4 stuff. I'm sure the BMW dealer will be closed tomorrow, so I'll have to make due with another brand.

[Kevin - Blown 95 TA]

What difference does it make if you bleed it at the ABS module first or not? You're still pulling fluid through the module from the reservoir, so I don't see what the big deal is. Not being a butt, just asking a logical question. I know that when we do a brake flush at work, they pull it from all 4 calipers until it's clear, which usually ends up taking at least 1 bottle of DOT4 to do.

The difference is that there might be pockets of air or old brake fluid that won't come out the brake line, but that will come out the bleeder because of where the bleeder is positioned on the unit.

[TraceZ]

Well, the job is done guys. It was pretty simple, and puting teflon tape on the bleeders really makes a difference. I did it with all of them. I took it for a test drive afterwards and made several ABS assisted stops from 35 mph without any trouble.

Thanks again for all the great help.