I have been trying to bleed the brakes on my 1600 circuit car it's been sitting for many years so i have replaced the master cylinders. It has some 4 piston calipers on the front and runs disc rear with two master cylinders using a balance bar of the peddle. The back brakes have been bled and are now working and the front lines bled but i cannot get any fluid pressure out of the bleed nipple on the caliper. The peddle feels very firm but front has no presure. There doesn't seem to be any leakage from the pistons. Does this mean they have rusted up? Any tips on freeing them or am i just going to face up to having the calipers rebuilt. As i think they are some scarce nissan competion calipers.......

cheers Paul

If nipple is open, and pedal is hard.The problem isn't the caliper at all, sounds to be the master.

even if the caliper was rusted shut, pushing the pedal will push fluid from the master to the caliper(with nipple open) it will pour out.


Also it is a good idea to rebuild them if they have been sitting there. brake lines only have a life of around 6 years(rubber)
and let water into the lines, which means insides of masters, lines,calipers start to rust up.
Personally I would pull it all off and pull it all down. Its brakes... Your playing with your life and others on the street/track.

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Have you cracked the bleed nipple or taken it out altogether?

They do block up over time, and there's no way for the fliud to escape, even when you crack the nipple. Take it out altogether, and then clean the holes with a bit of wire. If the nipples are OK, then it's probably the master cyl, or possibly blocked rubber hoses going to the calipers (I have also seen that happen before)

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