Re: Milano/ABS

[Lars Arvidsson <arvid@domain.elided>]

[Jean wrote:]

What is the secret to bleeding the ABS system when the pressure pump or
master are replaced?

I just replaced the ABS accumulator and still have system problems. Soft

pedal, hard pedal, anti-lock light coming on, sometimes staying on until
key
off, sometimes going out on its own. When the warning light is on, the
ABS
does NOT function. Having read Shiv Sikand's ABS debugging tips
http://reality.sgi.com/employees/sikand_mti/absdebug.html, I may
conclude
that the master needs replacing - I blame this on a previous owner's
negligence! I may also have a fault generated by a loose (in spite of
being
new) rear wheel bearing.

[My reply:]

Well, I did that operation this summer. Finally replacing the pressure
accumulator,
when hot under the bonnet the pump would never stop running.
I also replaced all of the brake fluid.
Even if I bled the system "by the book" it took 3-4 tryings to get it
OK, and almost 1 litre extra fluid
through the system. And it wasn't easy doing it on my own.
Start with front calipers, opening bleed screw with the ordinary
hose-and-bottle attached.
Slowly press brake pedal 'till it hits the floor, keep it threre for a
few seconds, quickly release it. Repeat
up to 10 times, and at the last stroke, keeping the pedal down until
tightening the bleeding screw.
That was a tricky one on my own... I put a rod between brake pedal and
the steering wheel and then hurried out
to tight the screw.  Repeat on the other front caliper. And adding
fluid.
Then the rear...
Turn on ignition, pump will engage. After replacing the accumulator,at
this point, I could hear air bubbles reaching
the pump intermittantly.  Attach bleeding hose to one of the rear
calipers, slightly depressing the pedal and keeping it
there, until quite a lot of brake fluid has flown out.  That rod was
useful again, pressing the pedal for me, while
I was somewhere under the car, trying to reach the calipers...
I had to repeat this procedure a couple of times before the pedal felt
hard enough. By a lot of brake fluid, it is no fun when
there is just an empy can when half-way finished, and a long way by bike
to get more...:-)
The adjustment of the handbrake clearance
of the rear calipers is also important to the feeling of the pedal.

all the best
Lars

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End of alfa-digest V7 #965
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