I am on my 3rd coolant tank cap!!! We have replaced the coolant tank and it was running almost too smooth for too long. Drove it for 15 minutes in 95 degree Alabama heat yesterday and the disco started heating up....pulled over popped the hood and sure enough the tank and radiator was empty...filled it up with water, got almost back home and it started heating up again, noticed water pouring out from under...popped the hood and the cap to the tank was still on tight, but water was coming out from under it. I have checked the oil to see if it is milky in case the head gasket finally went out, and it all seems fine. There is no leak underneath that I can find. Just ordered ANOTHER cap.....is this pretty common with the coolant tank???