Head Gasket

[Trumps01Cobra]

I have a 01 cobra p1sc and after replacing a hose that the harmonic balanacer rub through, I have now noticed that i cannot keep coolant in the car. I have replaced the hose, changed coolant 3 times and 1 time at mustang shop. Didn't the normal requirements for refilling. Now i'm thinking it may be a head gasket. I have changed the thermostat as well and still no luck. Any ideas?

 

[97rmcobra]

Pressure test the coolant system just incase you have an external leak. If not do a cylinder leak down test to see if the head gasket is blown.