my 1993 buick park avenue 3.8ltr engine keeps overheating. what is the problewm

your engine is airlocked. after replacing all these parts, and topping up the coolant, you need to do exactly what GM calls for and that is 'burping' your engine. start it up in park, let it warm up a little, rev it around 3000rpm for 10-15 seconds, then let it return to idle for a minute or so, then rev it up and hold it again, then let it idle. do this two or three times, then shut the car off and let it cool. fire it up and take it for a drive. if the problem is not fixed, try again, maybe jack up the front of the car just enough to make sure the rad cap is the highest part of the cooling system, and rev it up again. spinning the engine up at higher rpms like this makes the water pump pump faster, eventually pushing the air bubbles through and out the rad cap/overflow tank. this is GM's official way to do this for most of their v6 cars, like the impala, buick lesabres and park avenues etc, malibu, grand prix, you name it. these v6s can be hard to get the air out of, but with this technique weve been able to fix most of these issues simple as that. good luck source: 12 years as an automotive technician, with a couple years at GM specifically

Air in system. Bleed air like this. Remove cap from overflow tank fill with antifreeze to full mark leave cap off and start vehicle and let idle once vehicle starts to reach operating temp thermostat starts to open antifreeze level in tank will drop add more antifreeze to full mark then put cap back on. Also you will notice level in tank will start to rise this is normal and will drop once thermostat starts to open.