overheating, light flashing, air in system? how do i release air?

[986_inquiry]

My car was losing coolant, light would flash and it would boil over. Wasn't really overheating, mechanic said it was holding a good temp at ~210 and wouldn't get any higher, probably just a cap

I replaced the cap with the new one, the .4 one (forget the whole number, you guys know what i mean)

It's not boiling over now, but it still has the light going on and the needle climbs to ~210

mechanic says it might be a bad sensor? Does that make sense?

I've also read it can be air in the system and you just need to release it
"Sometimes it takes a couple of weeks of driving with the bleed valve open to clear trapped air in the system. It is fine to drive the car with the bleed valve open"


I've never flushed the coolant because it's suppose to be "lifetime" but I'm seriously considering it

Pedro's Garage went to 190,000 miles before flushing and said the coolant looked surprisingly clean and clear

so what should I do? I hate warning lights flashing at me, but if it's really nothing I'll try to ignore it

UPDATE: ummmm.... huh, while writing this I found instructions on how to bleed the coolant system

1. Remove the engine oil and coolant caps
2. Remove the plastic cover that is under the caps
3. Lift the bow on the bleeder valve
4. Fit the protective cover (this is a plastic sheet that has a hole in it that fits around the coolant fill area and covers the trunk in case the coolant splashes out when the engine is turned on. You probably do not need this but the time I did it I used a large piece of cardboard with a hole cut in it)
5. Top off the coolant to the MAX mark
6. Strart engine and warm up to operating temp at APPROX 2500 rpm. Briefly rev engine to APPROX 4200 rpm once each minute until operating temp is reached. This will take approximately 10 minutes.
7. Switch off engine and let cool
8. Top off coolant to MAX mark
9. Lower bow on bleeder valve, replace plastic cover, engine oil and coolant caps.

so I'll try that, thanks guys!