Why did you change the caliper? Brake hose is closed internally? Possible bleeder passage obstructed. Very rare are but it is something.


Could be rubber in the master is not coming back enough to fill the space ahead of the piston with fluid. The fill port is blocked. That is probably about all the possibilities.


Tests. Loosen front brake line fitting at master. Fluid comes out as master drains down a little. The rear portion of the master. If it does tighten it. loosen brake hose at caliper. Fluid comes out? If not your brake hose is closed internally.