Re: 1968 Cougar Overheating @ idle
Without the fan shroud, the fan is not concentrating the air flow through the radiator. It is essentially just throwing the air all around the engine compartment. You need the shroud to help force the air through the radiator which is where you get the majority of your heat exchange in order to cool the engine properly. You don't have that problem when you are moving because nature is taking care of that for you. You may also want to flush the radiator just in case the tubes are clogged in there as mentioned above.