I have searched, found ton of information but still in doubt of what caused the problem. Below is what have took place in last 36 hrs.

Yesterday I changed the stock AST over to a Pettit unit. Started the car ran for 15 minutes let it cool off, added coolant, & test drove the car 5 miles...no leaks...from PFC coolant temperature was 87* C.

This morning took the car to work (20 miles in rush hour traffic), temperature hoovered 87*-91* C (when AC on). Parked the car, check for leakage, none.

45 minutes later there is good size puddle of coolant right below the over flow tank. The leak definitely was from the overflow tank 100%. Right by the AST cap there is very small amount of coolant.

What's wrong? did I overfilled the radiator? what action need to be taken?

The AST was purchased used along with a 13 psi pressure relief cap...should I change the cap to a new unit?

Also the stock ast cap wasn't pressure relief so why should I use a pressure relief cap?

Thanks in advance.

 

well...off to the part store for a new AST cap.

Thanks.

 

Update: installed a new ast cap (13 psi), filled the ast, drove 20 miles home in stop-n-go traffic, 97* ambient temp, 101* heat index.

PFC show 94* with AC; 89* AC off.

It has been 45 minutes and no leaks, no gurgling.

Y'all are great.

Thanks.

P.S. Driving an RX7 in 101* heat index weather sucks!!!!!