Is it necessary to bleed the brakes when replacing the pads and rotors? I have always been told that as long as you don't open the bleeder valve and just use the caliper compressor tool it is not required to bleed the brakes since no air was allowed to enter the system. True or False?

 

Usually, that is true.

Good practice is to open the bleeder screw when compressing the caliper to allow the dirty fluid to exit .When done the brake pedal should only be depressed the same distance as usual and no further, several times to allow the pads to get to the best position for stopping.If the brake pedal is allowed to go all the way down , that move can cause the cups in the master to be scored by the sediment in the bore and can result with internal leakage and a pedal that will not hold pressure when applied.