what would cause the upper radiator hose to pop out? on 1997 Chevrolet Lumina

The coolant level indicator on the dashboard is always on despite having the radiator and the resovoire filled to the brim

Asked by for the 1997 Chevrolet Lumina
If the engine is over heating it may build up pressure and cause the hose to blow off. Make sure the radiator cap is OK it should open and allow coolant to blow out the cap prior to blowing off a hose. Does the cooling fan operate at the correct temperature? Another possibility is a stuck cooling system thermostat. It could be many things, unfortunately and without experiencing the problem first hand or being able to do some basic diagnostic tests its hard to say.
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I agree with last answer, also a possibilty of high amount of exhaust fumes building up from a bad head gasket. a simple test to be done whould be a Block test your local automotive shop can perform that for you.