Just replaced the TPS on my 2004 XJR. Upon removing the coolant hoses from the throttle body I was expecting to have coolant drain out, but none did. I did hear a slight gurgle. The main radiator tank is full. My question is, is the throttle body coolant source the same as the intercooler coolant source? And is that a separate system from the main radiator? I know there's that fill plug on top of the motor. Could someone explain that system for me please? Thanx.