Having now tracked and auto-X a few times I though it's time to change/bleed my brake fluid. I am still running with the fluid that BMW put in and the level in the reservoir is close to the minimum level.

The manuals say that "E46 cars require special BMW service equipment to properly bleed the ABS/DSC sytem. For safety reasons, the brake system on these cars must not be bled without the use of a factory diagnostic computer".

My questions are:
1. Can it be done DIY without worrying about the computer?
2. Why is the fluid level lower? Has it been boiled?
3. The brakes still feel good, but since I track the car I probably should change to a racing fluid. How good is the fluid BMW use?

i would use ate blue(i think thats what it is, if not im sure someone will correct me :) )

i dont know about the computer part. i know tho that when i watched the techs do it b4 a de inspection they changed the fluid without any computer.

The fluid level is low probably because the pads are worn.

The ABS and DSC systems have fluid chambers that cannot be bled without the DIS cycling the valves. How important is that? Not extremely important.

Replace your pads and use ATE Type 200 (gold). Technically speaking, ATE Blue is not DOT approved, and some inspection stations may fail you if they want to be anal. Other brands of fluid recommended include Motul, AP, and Castrol. The absolute best brake fluid out there is Castrol SRF, but at $75/liter, it's worth its weight in gold. It does have a higher wet boiling point than most high performance fluids when dry. We use Motul and ATE for street/DE, and AP600 for track use.

The fluid level is low probably because the pads are worn.

The ABS and DSC systems have fluid chambers that cannot be bled without the DIS cycling the valves. How important is that? Not extremely important.

Replace your pads and use ATE Type 200 (gold). Technically speaking, ATE Blue is not DOT approved, and some inspection stations may fail you if they want to be anal. Other brands of fluid recommended include Motul, AP, and Castrol. The absolute best brake fluid out there is Castrol SRF, but at $75/liter, it's worth its weight in gold. It does have a higher wet boiling point than most high performance fluids when dry. We use Motul and ATE for street/DE, and AP600 for track use.
Yeah, James is right... BMW will tell you not to bleed the brakes on the E46 because of the valve-controlled fluid chambers, but you can still bleed most of the system and everything works fine afterwards. Done it to several cars, no issues.

Good luck!

Steve

Having now tracked and auto-X a few times I though it's time to change/bleed my brake fluid. I am still running with the fluid that BMW put in and the level in the reservoir is close to the minimum level.

The manuals say that "E46 cars require special BMW service equipment to properly bleed the ABS/DSC sytem. For safety reasons, the brake system on these cars must not be bled without the use of a factory diagnostic computer".

My questions are:
1. Can it be done DIY without worrying about the computer?
2. Why is the fluid level lower? Has it been boiled?
3. The brakes still feel good, but since I track the car I probably should change to a racing fluid. How good is the fluid BMW use?
The trick is to activate ABS and DSC and then bleed it again. Flush your fluid, get DSC and ABS to engage, then bleed again. I've done it a dozen times in the last year w/o any issue on the street or at the track.

Fluid looks low because the caliper pistons are extended to keep the pads near the disc and shorten pedal travel. When you press the pistons back in to change the pads, the fluid level will be at the top again. BTW - this means don't top it off before changing to new pads!

top off the fluid
pressure bleed
take the car for a drive and engage the ABS a couple times, preferably not with a VW bus right on your tail
pressure bleed again

top off the fluid
pressure bleed
take the car for a drive and engage the ABS a couple times, preferably not with a VW bus right on your tail
pressure bleed again

ok, so i didn't use bullets.

The fluid level is low probably because the pads are worn.
I actually changed the pads from OE to Porterfield R4-S after my first DE and they are still not that worn. Can there be other reasons than pad wear for loss of the fluid? I did not bleed the brakes when I changed the pads and the fluid level has gradually decreased.