ABS Confusion

[Markus]

I am contemplating the purchase of an ABS bleeding tool. The instructions in the Helm manual indicate (generally) that, with the tool, you turn the ABS pump on and then open some ABS valves. After this, you bleed the brakes normally.

How does using the tool get air out of the HCU resevoir and where does the air go? Unlike normal bleeding, the tool does not actually expel brake fluid from the hydaulic system. And, more importantly to me, how does the ABS tool faciltate FLUSHING fluid in the resevoir? It seems to me that for flushing the fluid from the resevoir you need to open up a path from the master cyclinder to the resevoir to an open caliper bleeder. Can anyone enlighten me?

 

[SHOZ123]

Most ABS brake bleeders will cycle the valves while you are then bleeding the brakes at the same time. As long as there are no openings between the MC and the ABS pump and you do not let the MC run out of fluid there is no air introduced. I think. :corn:

 

[rangerj]

A little clearification is needed here. The ABS Bleeding tool has the ABS computer set the valves in the ABS in position for bleeding. Once they are in position the ABS bleed screw can be opened ONE AT A TIME while pressure is applied to the brake pedal (just like the rest of the brake bleeders).

The ABS cannot be bled unless the valves are in position for bleeding. You can activate the ABS on wet or slippery surfaces and get the valves in position BY CHANCE if they just happen to end up in the right position when the ABS stops.

Once the ABS is bled (two bleeders IIRC)then the rest of the system can be bled using the recommended proceedure, ie RR, LF, LR, RF. If there is no air in the ABS it is not manditory to bleed it. If the master cylinder has been pumped dry, say due to a leak, then the ABS most likely has air in it and must be bled.

I have had a Ford dealer pump fresh fluid through the whole brake system, including the ABS, for about $100 every couple of years. I supply the fresh brake fluid (Castrol GT LMA [Low Moisture Activity]). Consider thisif you do not plan on doing a lot of work with the ABS scanner. Is it worth owning?
rangerj