Daniel Boone

Overheating! Have changed thermostat. Changes water pump today. Had vehicle at dealership earlier week. Dealership tested for exhaust in coolant…no exhaust. Ran for an hour trying to burp system. Heater blew hot initially then stopped and blew cool air and hoses to heater core cool to touch. Bottom radiator hose cold to touch.engine will overheat when raining rpm’s. What’s up? Please help!