Patent ID: 8556186

Claim:
A fail safe engine coolant thermostat comprising: a housing adapted to be mounted in an engine coolant flow passageway; a valve plate mounted in the housing movable between a coolant flow blocking and a coolant flow allowing positions in the housing, the valve plate coupled to the housing in a position tending to allow the valve plate to normally pivot to the fluid flowing allowing position; a thermal responsive actuator mounted in the housing; a connector coupled between the thermal responsive actuator and the valve plate to move the valve plate to the flow blocking position at a low coolant temperature to move and the valve plate to the fluid flow allowing position at a higher coolant temperature; and a pivot connection of the valve plate to the body being connected diametrically off center to define a larger surface area on the valve plate to one side of the pivot connection and a smaller surface area of the valve plate to the opposed side of the pivot connection whereby, in absence of a workable connection between thermal responsive actuator, the connecting member and the valve plate, the valve plate can freely pivot to the coolant flow allowing position under the influence of the force of the coolant flow differential on the larger and smaller surface area portions of the valve plate.