Senior Tech Team
Join Date: Jan 2005
Location: Granite Bay, Ca.
Re: Temp sender in radiator tank?
I would go along the closed loop theory myself. Or perhaps the zero sum theory.
Think of it this way: if the coolant picks up 5* as it flows through the engine, then it must lose 5* as it flows across the radiator to maintain steady state. If it loses less than that overall system temperature will increase. If the radiator provides more than a 5* drop the overall system temperature will decrease, at least until flow is reduced by the thermostat.
Now if the flow through the radiator is being limited by the thermostat, then we certainly do not need any extra radiator air flow from fans. So we only need to worry about the case where the engine generates more heat than the radiator loses. In which case the radiator exit temperature will rise, turning on the fans to increase cooling when needed.
I see two potential issues with fan thermoswitches mounted in the radiator exit tank:
1. the temperature setting of the switch will need to be offset by some amount. The 175/195 numbers sound like about the right offset for a 180* thermostat system.
2. many of the thermoswitches are single wire grounding switches and rely upon their mounting ground to operate. Many radiators are rubber mounted and thus insulated from ground. So no worky. Would need to either ground radiator or use 2-wire thermoswitch.
1968 El Camino, 402 with TKO