Gates 33036S Thermostat Premium; 160 Degree Superstat (2-1/2" x 29/32" x 29/32") Opens against the flow of coolant from the water pump The coolant, under water pump pressure, is used to help the reverse poppet thermostat stay closed when cool to reduce leakage The offset thermostat with jiggle pin valves is equipped with a special valve in the flange