I bought a Buick Century for my son. In the process of fixing it up. I have a problem. I put a new water pump in the car and flushed the cooling system. Now the car will not air bleed. It keeps running hot . I have bled it by the book for hours. Got it to where it has heat and temp sits in the middle. When I drive it it does to 3/4 and loses heat. If I keep driving it it eventually goes to red. When I check it it is totally air bound again. There is no coolant leaking from the intake or anything. It does not smoke from the tailpipe like a blown head gasket would, and there is no coolant getting into the oil. I also put a new thermostat in it today. Did not change a thing. Did I mention that the car runs fine, no skips etc. Could it still have a cracked head or something like that?
It really could be a lot of things, unfortunately. Do you have any history on the car? Why did it need a new water pump?
Some random thoughts:
1. Possible the radiator is clogged? That would take a long time to show up while idling, but appear very quickly once driving 2. Possible the fan system is bad - switch, fuse, relay, motor? That would not show up quickly on the freeway, but very quickly driving on surface streets 3. Possible the belt routing is wrong? A friend of mine once did this - took me forever to find he was spinning the water pump BACKWARDS. 4. Possible you have a bad hose or seal that is expelling coolant or sucking air in? Air in the cooling system can have a lot of effects - bad thermal management, bad flow, apparent overheating as air expands faster than water. 5. Possible you have a clogged or failed thermostat? That would take a long time to show while idling, but show up quickly while driving. Could also make bleeding the system difficult by trapping air in the radiator.
If you don't have one, I would consider buying, renting, or making a cooling system pressure tester or visiting a shop that has one. Putting 15-20psi in the system will expose most cooling system leaks. It wouldn't show you anything else, but might still be helpful.
[This message has been edited by thesameguy (edited 05-22-2018).]
Go to your local auto parts store and get a block tester. You can rent it, but you will have to buy the fluid. That way you can test and make sure that no combustion gases are getting in the coolant. First thing I would check before wasting any more time/ money