Abstract: A radiator cap is provided with safety venting character for use with a coolant recovery system. The cap is provided with lever means which compel safety venting of excess pressure in the radiator before the cap can be removed, the venting being effected automatically through a selectively movable valve that is moved to an open position by actuation of the lever means. The cap serves as part of a coolant recovery system, with the selectively movable valve also serving as the valve that automatically opens to permit siphoning of coolant back into the radiator during the cool-down portion of the coolant's heating and cooling cycle.

Abstract: A limited torque cap is provided with a construction wherein a cam ring is located concentrically within a plurality of at least three radial movable jaws, normally biased inwardly and arranged to provide a driving connection with the cam ring until a predetermined level of torque is applied to the ring-jaw connection. A further construction is provided for effecting axial movement of the cam ring relative to the jaw members after a predetermined torque is achieved, whereby to prevent re-coupling of the cam ring and jaws and effectively "locking" the cap against further tightening to its connection and against removal. An "unlocking" feature permits selective restoration of the ring-jaw connection.