I have an 87 Firebird Formula 5.0. What is the engine temp before the cooling fan comes on. I have let go up to 220 and it still doesn't come. I have changed the thermostat, fan relay and temp sensor.
Also, after idling for a short period of time and the temp is only like 180 I get boiling or bubbling in my overflow tank. Any suggestions and thank you for your time.!

Rob in Harvest, Al

well, replace the temperature sensor for the fan and pray that's the only problem, it should come on long before 220