Car overheats need advice?!

So I got a 2001 Honda Civic the guy I bought it from said it had a new radiator and rebuilt engine bought it for 2400 in March was gonna pay him the 200 later but anyways in May I went to Anaheim and that's when my car started overheating for some odd reason took it in ended up needing a new thermostat and the fans blew out hot and cold got that fixed but also there was a leak mechanic said it could be the gasket. Anyway 3 week ago got into a fender bender had to get a lot of new things including a new radiator! My car still overheats yet the mechanic can't figure out why cuz ever time they test it it's fine! Could it be the water pump

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