I have mine in the hole between #2 and #3 cylinders on the left side of the head right above the exhaust. I don't think the exhaust has much to do with heating the sender. The tip is what reads and its deep in the head under water. Even if it does, the water is that hot anyway, so its still accurate. Mine reads hotter then the thermostat or radiator, so if the gauge shows hot, I know I have a safety margine of a few degrees before overheating. Joe