MX83 brake master - WTF?!

[Adash=P]

My Cressida was sitting around for about 3 months and the master started leaking. I pulled it apart and replaced the seals.

Now there is plenty of pressure going to the front brakes but nothing to the rear. I've tried replacing the seals on another and its still the same.

I've bench bled it aswell.

[big_zop]

Proportioning valve stuffed by any chance?

[MR22ZZ]

bled the brakes or bled the master cylinder itself?

[Adash=P]

How can I check the valve to see if its any good?
I've bled it at the calipers and the master. When its the vise, I get plenty of pressure at the top outlet but nothing at the side one.

[big_zop]

Not sure on the proportioning valve, but if you have tested it on a vice and are getting no pressure coming out of the master itself, then that looks like your problem.

[Adash=P]

But I've put fresh seals in and I've tried it on two different masters.

[big_zop]

So how are you measuring/reporting that you have no pressure at the side outlet?

If its while its on the vice, then it looks like you got 2 dud/blocked or otherwise masters. Are you using the same shaft in both?

If its in the car then there is all the other things (lines and hoses. joints, prop valve, calipers) that can hide the problem and you will need to either test each and/or replace with known working components till you isolate it.

Are you bleeding the brakes with the furthest from the master first? Manually or mechanically, with a helper? Are you getting any fluid out of the rear bleeders? Managed to install the rear calipers upside down?

[frostyadonis]

[IMG][/IMG]

have you fitted your piston the wrong way perhaps?
springs in the right place? seals not back to front?
return spring in place and is the piston actually returning?

or maybe the second circuit has a leak thus not enough hydraulic pressure to push the first circuit to allow fluid pressure for the rear brakes.
this is a built in safety requirement for all masters.
pull master away from booster. should be wet if its leaking (around rear dust seal)

[frostyadonis]

also when your bench bleeding is fluid squirting out of the rear brake line port as well as the front?

[petergoudie]

I'm with frosty. Seals or piston around the wrong way.

[Adash=P]

So how are you measuring/reporting that you have no pressure at the side outlet?

If its while its on the vice, then it looks like you got 2 dud/blocked or otherwise masters. Are you using the same shaft in both?

I put me finger over the front outlet and if I push the piston in, I can only hold it so much till it starts spewing fluild out. When I do this, I can hear air coming in out of the rear outlet and its seems its not sucking in any fluid.

have you fitted your piston the wrong way perhaps?
springs in the right place? seals not back to front?
return spring in place and is the piston actually returning?

or maybe the second circuit has a leak thus not enough hydraulic pressure to push the first circuit to allow fluid pressure for the rear brakes.
this is a built in safety requirement for all masters.
pull master away from booster. should be wet if its leaking (around rear dust seal)

I put everything back the way it was in the correct order and the seals the same way around. Yeah the piston comes back if I push it in. It was leaking, I took it apart, replaced the seals and now this shit. Its not the first time I've refreshed a master cylinder. I've done it several times and never had a problem.

also when your bench bleeding is fluid squirting out of the rear brake line port as well as the front?

Plenty coming out the front nothing to the rear.

[frostyadonis]

masters can be bench bled by blocking the ports off
so no air is drawn in when the piston returns
some places use threaded plastic blockoff plugs
or spare crimped pipes with the nuts tightened
the air escapes through the reservoir
just keep bleeding untill all the air is gone
be gentle with it or you'll get squirted in the eyeballs