Hi again, There are three problems that usually cause overheating thermostat, cooling fan and coolant leak. You said the cooling fan works and the thermostat is new so have you had the cooling system pressure tested to check for leaks? If not that is where I would start. The water pump doesn't usually cause a overheating problem unless it's leaking. Did you replace the radiator cap with the radiator? If not I would have it pressure tested too. Now because there was rust/gunk in the radiator I would have the cooling system flushed to try and remove as much as possible. A engine problem can also cause overheating [head gasket] I would make sure there are no leaks first and that the radiator cap is okay first.

I hope I have been helpful,
Bryan.


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