I had pulled my turbo earlier to port the wastegate and I lost a fair amount of coolant. When I refilled the coolant and went to start it today, leaving the rad cap off, it started fine and ran for a few minutes before the temp gauge (aftermarket gauge in stock position) started to go up really quickly. It climbed past 250 within the space of a minute before I killed the car and let it cool. After only a few minutes the gauge was back down to 150. I think it is just a air bubble, but I'm not sure how to get rid of it and I'm scared to run the car to let it work itself out. Any input?

 

Well, it seems to have worked itself out since everything was normal when i went out and started it again just now. Mods, delete this if you feel it needed.