[j persons]

Most good thermostats have a small hole or are V notched at the top. So there is ALWAYS a small amount of flow going thru it, even when the engine is stone cold. So both sides of the thermostat have the same exact temperatures.

Z

^ what he said. I've used the thermostat port on a couple of engines, usually for a fan switch. When I first did it, I was concerned that it wouldn't give an accurate temp reading until the thermostat opened, but testing with an infrared thermometer showed that the water temp on the rad side of the thermostat was the same as on the engine side. You do need to add a 1/8" hole in the thermostat as a by pass, it will help in burping the system.