Temperature gauge fluctuating

[ptaylor]

I have a 1999 Explorer, the radiator had a crack in it and my husband replaced it. My son drove it to church and when he turned the engine off it made a loud bumping sound when we raised the hood it was the two hoses coming from the firewall. My husband replaced the radiator cap and the heater control valve. The hand still was fluctuating and we were told it was air locked. We took it to our Ford dealer and they got the air out of the system, the hand still fluctuates and you can still hear the bumping noise on occasion. Could there still be air in the system or is there something else going on?

 

[arco777]

Welcome to the forum!

The thermostat opening and closing can introduce a fluctuation into the system. A sticking thermostat can cause wider fluctuations and can even cause damage and overheating if it sticks closed. It would be worthwhile to check the thermostat for condition and proper operation.

There could always be air in the system but it is not too hard to get the air out yourself.