My water heater has been leaking out the TP Valve. We installed a new one to see if this would help, but the new valve leaked as well. I tested my Expansion tank to see if it had air in it and the pressure would not register on my gauge, so i took the needle out to see if there was any air and there was no air, but there was also no water leaking out as well so the bladder must still be good. For some reason i am not able to increase the air pressure. I have put my trusty tire pump on the tank and it won't air up. It is as though the valve stem is not long enough for the mechanism inside the pump to unseat the needle and allow the air to go into the tank. Can someone help me because i think the tank is still good and i don't want to spend the $40 on a new tank if i don't need to.