Thunderbird,My car still overheats, I replaced water pump and thermostat, and now after water pump install it knocks bad

So my girlfriends car is a 96 thunderbird, yesterday it started overheating, I replaced the tstat, didn't work, then replaced the water pump, no luck, and now since I replaced the water pump it knocks. We absolutely need this vehicle and I would really appreciate some advice

My car has 155000 miles.
My car has an automatic transmission.