[gearbanger]

I disagree that it won't have any effect on the cooling. But I think it has a positive effect. The heater circuit allows water to be circulated through the engine and back to the heater without ever circulating through the radiator. So you constantly have part of your water not going through the radiator. If the heat is not switched on and the blower not running as is always the case in the heat of the summer, you will not be giving up any heat at the core so, by not circulating all the water in the radiator you are losing cooling capacity. I think blocking the heater circuit, not just connecting the lines together like I have seen some do, will actually make the engine run a little cooler. I may not make a dtectable difference on the guage but I think if there is any change it would be to the cooler side.