One of my back rotors is not getting hot. Both calipers are new and there is fluid coming in the line. 3 of my rotors get hot, this one just does not.

 

bleed em again! RP, RD, P, D, farthest from the master cylinder to the closest to the master cylinder, when you bleed em see if the cold rotor side bleeds as well as the others, my guess its either air, bad lines, or a jacked up caliper. when u bleed just let the pedal go halfway to the floor, not all the way. good luck, hope it helps!

 

maybe my pads are in rough too? My other caliper issue is fixed. Two new calipers. Both lines to the back have flow. I bled rears and both had fluid. I did not do the front, must I? Is this what is the problem?

 

you need to bleed them all, and if you did recent work on them (as it sounds you did) you may want to bleed quite a bit to make sure your getting all the air out of all the lines. also keep your MC topped off so you dont get air in it.