Subaru 2002 Outback with the H 6cyl engine

Greetings,
I am having an engine temp issue when climbing steep hills. The gage goes from normal to the red line but not into the red. The VDC OFF light is on but the CEL is not one. Once I reach the top of the hill the engine begins to cool off and returns to normal. Yesterday I had the radiator flushed and the thermostat changed. Am I looking at a water pump or head gaskets?
~~John

I don't know your car, but frankly, Going up to but not exceeding the redline seems normal to me.  What are the cooling fan(s) doing?  Are they on?

No, that is not normal.
I had the same model Outback, and I never experienced any instances of the temperature gauge getting anywhere near the red line, even on the hottest day, and even on the steepest hill.

While the H-6 3.0 engine does not have a history of head gasket problems, it is possible that you are experiencing this problem. Have your mechanic use his exhaust emissions “sniffer” to check for exhaust emissions in the cooling system.

Hopefully the trouble isn’t with the headgaskets but it sure is possible. If the test shows no problem with that I would suspect a partially clogged radiator is the cause of the trouble and replace it.

I’d have them check the radiator, they can do that pretty accurately with an IR thermometer, check for ‘cool’ (non-flowing) areas.

Could the water pump be my problem?

~~John