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Bleeding RR ABS brakes

1991 Range Rover with ABS

I hate brakes! I need some help/advice please folks. After having changed the two OSF flexible hoses and replaced three other brake pipes I'm now having difficulty bleeding the system. I've followed the Haynes book of wisdom on how this should be done on the ABS brake system but to no avail. Almost had it yesterday, but the booster pump would cut in after the first brake press and release (Haynes reckoned I should be able to press twice without the pump cutting in). Have tried another full purge today and, although the bare (non-assisted) brake pressure is nicely rock hard, the pump now runs continuously and does not seem to bring the accumulator up to pressure. It almost sounds like the pump is cavitating or chasing a bubble, but I can't get any flow from the accumulator bleed point. Yesterday the fluid would jet out el rapido as soon as the pump was run. I can't get any more air out of the LP side of the pump so I'm hoping someone here may have a possible solution or secret knack of how to get it right.

TIA for any help, Steve

Reply to
Steve
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Steve uttered summat worrerz funny about:

Never bleed ABS so the above is a mystery but I have bled standard RR brakes and now know to look for the trick extra nipple on each caliper that had me pissing around for ages... it'll be under some crud hiding at the top of the caliper at a guess.

Lee D

Reply to
Lee_D

Thanks Lee. The trick extra nipple has already been conquered and the system has been bled. It's this booster pump and accumulator that isn't playing fair.

Steve

Reply to
Steve

Hi Steve, have you evacuated the accumulator first? Press the brake pedal 25-30 times to get all the fluid back into the reservior, then start it up & let the accumulator pump do it's job for a minute or so. Then top up the reservior, worked for me.

If the pumps not switching off, the switch might be duff.

Reply to
Nige

Hi Nige - yep have pumped the accumulator down. On the first attempt all was well and on test the pressure light went out at about 20 secs and the pump cut out after 40 secs. The pump cut in again after the first press of the brake pedal though (according to the book you should get at least two presses before it runs again). On re-bleeding I'm now at the stage where the booster pump runs continuously and the pressure light stays on. There's also now no flow out of the accumulator bleed point even with the pump running. It almost sounds like the pump has an airlock (it runs sort of "Bzzzzzzzz-zizzzzzz-zizz-zizzz-zzzzzzzzzzz" - hard to write the sound it makes!!). Maybe the law of sod has compounded things by making the pressure switch fail and/or the pump shaft has broken. :-(

Steve

Reply to
Steve

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