Thread: Bleeding ABS brakes

1.5 litres is economical !!!! hahahaa

Don't try working on the brakes of a modern SBC/EBC controlled vehicle then. - minimum bleed for the diagnostic computer electronically controlled bleed cycle is 2.5 litres and max of 4 Litres.
Yes, you heard correctly!

Gone are the days where 2 people and a manual bleed with half a bottle of DOT4 was possible.

Actually, you don't need to do a full bleed if you're just replacing the line from the pump to the accumulator (or if you're replacing the pump, accumulator or lines from the accumulator to the booster and ETC valve if fitted). In all of these cases, you just need to bleed the ABS pump, accumulator or ETC block (if fitted) and the booster unit (the one the pedal is attached to).

However, it would be prudent to bleed the entire system to flush it if you haven't replaced the brake fluid within the past two years. Or, of course, if you suspect that air has been introduced to the caliper circuits (for example by depressing and releasing the pedal with the reservoir below the minimum level).

As Mercguy says, allow a full 2.5L or more for this. And, as you have obviously done, follow the manual meticulously.

The hydrostatic (or traditional or doesn't-need-to-be-pressurised-to-work) system is effectively the fail safe system which will work if power is cut to the ABS pump for some reason (for example, if the fuseable links burn out) and the accumulator has lost its energy (typically between three and seven applications after the pump stops). The hydrostatic system operates only on the front caliper lower pistons and in normal operation is pressurised along with the rest of the system (it needs to be for the ABS to do its job). Mind you, with the accumulator de-energised, it barely stops the vehicle at walking pace.

Thinking about your question regarding the bleed order of the hydrostatic circuit (driver outer, passenger outer, passenger inner, driver inner), considering that the inner and outer bleed screws bleed the same lower channel in the caliper, I can only hazard a guess that it is not so important when doing the pressurised bleed that you would have done (ignition on, ABS running until it stops so that the accumulator and the system is fully charged etc.). I suspect the order is more critical when bleeding an emptied system after replacing or overhauling the calipers and the first bleed of the hydrostatic system (using the traditional method) needs to push out all the air in the lines. I suspect that once the driver outer is bled, the time taken to do the passenger outer and inner allows any air in the driver caliper to float to the top where it is expelled when you do the driver inner last.

And of course, any little air particles will be expelled when you do it again under pressure as the last step in the entire ABS bleed process.