Ford Repair: 90 ford escort brake trouble, brake caliper, disc brakes

Question
 I own a '90 Ford Escort.  My front passenger disc brake was not releasing.  I thought the caliper was shot, but after recently replacing it the brake just started doing it again.  The wheel doesn't lock up.  My pads are rubbing the rotor.  It seems to work about half the time.  My rotor is getting hot and my brakes are smoking.  What else could this be?  

Answer
Several things can cause a brake caliper to lock up. 1-A restriction in the brake line or hose-make sure the hose is not kinked or damaged. 2-A sticking caliper-if you used a rebuilt caliper, they are know to not be the best quality every time. 3-Lack of lubrication on the caliper slides, allowing the metal parts to bind. DO NOT use just any old grease, there are special lubes for disc brakes that won't melt under heat. 4-If this Escort has anti-lock brakes, there could be a problem in that system, but I would expect the ABS warning lite to come on.

Disc brakes are designed to keep the pad against the rotor, with minimal pressure when not braking. Did you surface or replace that rotor? Is there a fluid or grease leak onto the brakes? On rare occasions the outer axle boot will split and some grease can end up on the brakes.