Gates 34044 Thermostat Housing Integrated housing thermostat; 180 Degree (35/34" x 3/4" x 3-holes) W/seal, jiggle pin 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