My 2000 Oldsmobile Intrigue keeps overheating when driving over the mountainous area outside of town. It usually occurs when coming back from drill (4 hour drive). The mountainous region is around the 3.5 hour mark. All the fluids are normal. Coolant is within the preferred region and oil is the same. But every time I climb the mountain it reaches to the overheat mark and I have to kick on the heater to save the engine. Is there another reason behind why it over heats?
Try replacing the pressure cap on the coolant reservior. This replaced the the radiator cap.
If the cap can’t hold pressure, the coolant starts to boil and the engine starts to overheat.
Tester
This looks like a classic case of the radiator or cooling system not being able to handle the load. You need to have the system flushed out if not already done. In addition, you may need a new radiator. Also check if the electric fan come son.
On a 13 year old car this situation is not unusual.