Gotta look where it's coming from. It could be as simple as a loose hose clamp on a radiator hose or as severe as a corroded head gasket. When the engine is up to normal temperature, the cooling system will be under about 15 pounds of pressure. That raises the boiling point of the water in the coolant mixture by 45 degrees. When any coolant escapes and is over 212 degrees, the water in it turns to steam. That should make it pretty easy to see where it's coming from. The good news is the gauge is showing a normal temperature. That is one tiny clue that suggests the problem is not a bad head gasket.
As an alternative, you can wait a half hour for the system to cool down, then use a cooling system pressure tester to pump the system up to pressurize it, then look for coolant running out. Small leaks like loose hose clamps often don't leak unless the system is pressurized.
Tuesday, February 1st, 2011 AT 11:25 PM