I'd like to allow coolant to flow from the heater outlet on the the head to help keep no. 4 from running too hot. I can't work out the best way to plumb this. I need a heater but I want to be able to shut off the coolant to the heater in hot weather.
How can I allow coolant to flow out of the heater outlet in the head whilst having the coolant supply to the heater shut off and where do I plumb the coolant back in which comes from the heater outlet?
If I plumb it back into the bottom hose then I'm bypassing the radiator and putting hot water back into the engine. If I plumb it into the top hose then I'm bypassing the thermostat and increasing warm up time.