My 2001 Chevy tracker has an after market fan behind the radiator fan I have to turn on to get it to run, it has a new aftermarket cap I switched back to old because after I fill my radiator it fills my reservoir tank but doesn’t seem to suck back into the radiator not sure if it’s getting to much pressure not enough, it works fine for a day or two then is about empty again any ideas

 

You may have to replace the radiator. It's pretty easy, I replaced mine a couple days ago, it only took about an hour (6 bolts, 4 hoses).