brake bleeding problems

[24v]

Hi All
I have fitted a mk4 brake servo to my mk2 but when I try to bleed it I have no pressure.I took the master cylinder off and stripped it down to see if there was a blockage but nothing.It will not draw in fluid when pushed but when left alone the fluid will drip out of the lower front pipe inlet.
Any ideas would be great.

[AndyG]

When I fitted a brand new (empty) master cyl. on my '96 MK5, I couldn't get it to bleed either

In the end, I decided to leave the front bleed nipples open and went indoors for at least an hour

When I came back to it, I found that I could finally bleed the system

The other way would be to use something like "Gunsons Easy-Bleed"

[24v]

Will try that thanks.

[Luke]

easy bleed usually does the trick i think it's a build up of crap in the old lines and the air pushing through at 1st doesnt have the pressure to blow it through

[Timbo]

As it is a non-standard mastercylinder you are fitting check that it can return fully to open the ports to the resovoir. If the plunger is being held in a bit by the rod on the servo then the ports could be closed or nearly so. Undo the nuts holding the mastercylinder and pull it away a half inch and see if the fluid flows in.

If that is the problem then check that the pedal is allowing the rod and servo to return far enough.

Some servos have a screw in section and lock-nut to operate the plunger of the mastercylinder and this may want adjusting in.

[24v]

Thanks for that.I will bleed using a kit tonight.
Also timbo I also thought the same and on my vacuum servo the rod to push the master cylinder plunger is threaded and adjustable .I played with this abit but to no avail.
Also the pedal is travelling enough.
I thought it might have been travelling to much at first and going past the resevoir inlet but all ok (I hope)

Will let you all know the outcome of the brake bleeding again tonight

[24v]

Got the bleed kit and still no joy.
Pumped in fluid from each caliper and found the problem.
A piece of grit in the bleed nipple was stopping the fluid when pressure was applied.
I did not notice it when I checked it on the bench where it had no pressure applied.
Bled it up and took it for a blast.

Hugh improvement over the old one and now am just bedding in the new pads I also treated myself too.

Thanks all for the tips and advice.

[AndyG]