Is it normal for the temp gage to climb from 180 to about 240 after the engine is shut off? Is this a sign of air in the cooling system?

 

It's called heat soak and it's perfectly normal. You'll notice it more in the Summer, especially on really hot days, but even in cooler temperatures you'll see the temp. gauge go up and then eventually start going back down as everything cools off. You gotta remember that when you shut your car off there is still a ton of heat in the heads, exhaust manifolds, pistons, etc..., and that heat needs to go somewhere, so it "soaks" into the engnine block and cooling system.

 

thanks!