I have a 2001 Nissan maxima, it overheated once at idle and went back to normal after driving. I’ve had two mechanics say everything looked fine. Today I did a pressure test, coolant is fresh, put a flashlight in the radiator, cleaned that, fans come on, drove it once doesnt overheat. Mind you, it’s about 40-50 degrees Farenheit where I live. What is some possible causes? Also I turned it on after a day of leaving it and there was a metal clanking noise which I’ve never heard before it stopped after about 10 seconds of the car being on. After revving the engine a few times, it shut off and the car was completely dead and making a ticking noise but my mechanic disconnected the battery and reconnected it, it turned right back on.

 

The overheating could be due to a failing coolant temperature sensor.

But not sure about the metal clanking noise though. Is it coming from the passenger side? The only thing that I could think of is timing chain clacking noise due to failing guides and tensioner.