Coolant Dump/Boiling/Overheating
 

Hi everyone!

I was driving and noticed the temp gauge greatly rising followed by flashing temp light. I pulled over and shut off my car and had Coolant completely dumping out from the rear passenger side, by the back tire. The Coolant tank cap was nice and tight so I loosened it a bit and steam began to shoot out followed by boiling hot coolant... I figured it was the Thermostat so I swapped out the thermostat, drained my coolant and put 5 gallons of new Porsche coolant back in. The next day, same issue. Car overheated, boiling coolant, then coolant dump from the back tire. I am at a loss.

Any suggestions?