CVO 9/19/2012Cooling system leaks -- Loss of coolant because of a coolant leak is probably the most common cause of engine overheating. Possible leak points include hoses, the radiator, heater core, water pump, thermostat housing, head gasket, freeze plugs, automatic transmission oil cooler, cylinder head(s) and block.
Make a careful visual inspection of the entire cooling system, and then PRESSURE TEST the cooling system and radiator cap. A pressure test will reveal internal leaks such as seepage past the head gasket as well as cracks in the head or block. A good system should hold 12 to 15 psi for 15 minutes or more with no loss in pressure. If it leaks pressure, there is an internal coolant leak (most likely a bad head gasket but possibly also a cracked cylinder or engine block).
It is important to pressure test the radiator cap, too, because a weak cap (or one with too low a pressure rating.
HouseCallAuto 9/19/2012On this 3.8 engine, there is a 90 degree elbow that connects the belt tensioner housing with the intake manifold on the pass side. Check here for a coolant leak as it is a very common area to leak and if it is leaking, let me know and I will provide some details that will help when you replace it.