Ducati 600ss brake bleed getting nowhere

 Hi,

I own a Ducati 600 supersports (money-pit), and have replaced the front
brake caliper as the old one had 3 out of 4 pistons seized. It's a hydraulic
system, master cylinder on the handlebars down to a 4-piston caliper (2
opposite 2) on the wheel. I've checked, double-checked that everything has
gone back OK, and I have spent nearly a day trying to bleed the air out
since the system was sealed, but am still left with no resistance in the
brake lever. I'm using a hose on the bleed valve, I am keeping the res
topped up with fluid (new DOT4), I drained the system before starting, and
am using a jam jar to catch the fluid and keeping the other end of the hose
immersed in this fluid.

I have tried leaving a rubber band holding the lever in while I do other
stuff, there are absolutely no leaks, and I am positive that no air is
entering. The fluid is returning to the reservoir, as it squirts out if I
try pumpimg the lever with the cover off, but I am getting pretty much
nowhere with the bleeding.

I started out getting some big bubbles, but all I get now is either good
fluid, or tiny bubbles like a fizzy drink out of the bleed valve. Am I
missing something, or should I just carry on and the air will eventually
escape? I've got a jam jar with about 3 quarters of a litre of new fluid
that's come out of the system via the bleed valve and hose, but still no
resistance on the lever.

Any help much appreciated before I have to re-mortgage the house for more
parts from Italy..... Thanks!

 wrote:

<snip>


Buy a Mityvac and grease the nipple threads before bleeding.

--
Pip: B12

 mentalguy2004 wrote:



If desparation sets in, you could try it the other way round and use a
big syringe to pump brake fluid in from the caliper end.
Grease the nipple threads, to stop air being drawn in around them.

--
Mike
FJ1200

 mb wrote:

Air being drawn in - that could be the problem.
Is the OP closing the bleed nipple before releasing the brake lever?

--
Eiron

No good deed ever goes unpunished.

 mb wrote:

Teflon tape works well on the bleeders as well.