Abstract: A coolant temperature control system of an internal combustion engine is composed of a thermostat disposed in a coolant passageway leading to a radiator. The thermostat is operatively connected to a diaphragm actuator so that valve opening temperature of a thermostat valve is controlled in response to engine loads. Additionally, the thermostat valve is arranged to be opened in response to the discharge pressure of a coolant pump, thereby lowering the opening temperature of the thermostat valve at a high speed engine operating range.

Abstract: A system for controlling a coolant temperature of an internal combustion engine comprises means for detecting operating condition of an engine, means for setting a different target coolant temperature for the detected operating condition, a flow control valve disposed in a coolant recirculating passage, and means for effecting a feedback control of opening degree of said flow control valve in such a manner as to adjust the actual coolant temperature toward the target coolant temperature.

Abstract: Disclosed is a piston ring assembly for an automotive internal combustion engine, including a first compression ring having double-stepped mating ends for reducing the quantity of blow-by gas, and a second compression ring which is constructed in the form of a double-ring structure adapted for reducing the quantity of oil consumption.

Abstract: An additional oxidation catalyst containing section is disposed in engine exhaust gas passageway upstream of a reduction catalyst containing section in said exhaust gas passageway at a location downstream of which an oxidation catalyst containing section is disposed.

Abstract: An auxiliary flow control valve is disposed in an exhaust gas recirculation passageway at a location upstream of a main flow control valve controlling the flow rate of exhaust gases recirculated into an intake system. Two conduits communicating with an intake manifold communicate with a vacuum chamber of a servo motor controlling the main flow control valve. One of the conduits has formed therein a restriction to limit the flow rate of fluid therethrough. A check valve is disposed in the other conduit to close the same when the vacuum in the intake manifold is increased and constant and to open the other conduit when the vacuum in the intake manifold is reduced.