Braking woes

[leblanc]

This year I replaced the rear brake cylinders. I also got a rebuilt master cylinder from a friend so that went on too. I bled the right rear first and then the left rear...no problems so far. Then it came to the front, tried the r. front no go, then tried the left front, no go next day I tried inhaling via hose and got left front to work, tried right front and never got anything. What should i try next. Oh yeah went from DOT 3 to DOT 4 also.
What should I try next???

 

[furyus2]

How old are the flex lines? They will swell up inside, and look fine outside. Somtimes you have to work your way backwards, at each fitting, to find out where you are getting fluid. Then you know where the problem is.

 

[65wgn440]

Are you getting strong pressure out of LF when you bleed ? If not, then maybe re-perform a good bench bleed of the master cylinder.

 

[AJ/FormS]

Make sure the compensating port is open, and filling the chamber, that is to say that the pushrod is backing up far enough.