Overheathing?

I recently changed the thermostat in my 98 4cyl Malibu and I let is sit for about 30 mins on level ground to ensure it didn't overheat; everything was fine but when I pulled in my driveway(steep incline)the car overheated, I backed back to the street and it dropped down some and when I pulled back up the drive it overheated again. Any suggestion on what can cause this?

You've got trapped air in the system

You've got trapped air in the system


Exactly.

There is a tint nut/cap on the metal line above the water pump just infront of the head and to the right of the diagram showing the accessory belt routing if you are looking at the engine. Loosen this nut ever-so-slightly with a wrench while the engine is running and warm. You will start to see air bubbles. When only antifreeze is seeping out without any bubbles, tighten the cap. You will probably want to do this once a day for three days to ensure all of the air is removed.

thank you guys for your help, I am going to take a look this weekend and hopefully have a car that works. Thanks again