A passive diverter fitting for a cooling system of an engine includes a base defining an interior cavity, an inlet opening extending through the base that is in fluid communication with the interior cavity, an outlet opening that is in fluid communication with the interior cavity, and a bypass opening that is in fluid communication with the interior cavity. The base is configured to be removably disposed in a cavity of an engine block. The inlet opening is positioned to receive coolant when the passive diverter fitting is disposed in the cavity of the engine block. The outlet opening is in fluid communication with the area exterior to the engine block when the passive diverter fitting is disposed in the cavity of the engine block. The bypass opening is in fluid communication with an interior coolant passage of the engine block when the passive diverter fitting is disposed in the cavity of the engine block.

A refrigerant control valve apparatus includes a valve body provided with a main control valve controlling the refrigerant sent to a discharge port and a temperature sensing control valve controlling supply and discharge of the refrigerant to a temperature sensing chamber. A fail-safe mechanism is provided which supplies the refrigerant to the discharge port in a case where the temperature of the refrigerant exceeds a set value. The temperature sensing control valve is set in an open posture in a case where the main control valve is in a closed posture that closes the discharge port and the temperature sensing control valve is set in a closed posture in a case where the main control valve is in an open posture that opens the discharge port.

A thermostat malfunction detection device that detects a stuck open state of a thermostat includes: an estimated water temperature calculation module that calculates an estimated water temperature of a cooling water based on an operation state of an engine; an actual water temperature detection unit that detects an actual water temperature of the cooling water; a first determination module that establishes preliminary determination when an amount of change of a difference between the estimated water temperature and the actual water temperature within a determined period is equal to or larger than a first threshold value; a passing air amount control module that increases a passing air amount, when the preliminary determination is established; and a second determination module that establishes malfunction determination, when the difference is equal to or larger than a second threshold value, after the passing air amount has been increased.

Provided is a thermostat monitor (36) comprising a thermostat open failure detecting part (38) for detecting an open failure of a thermostat when a condition is such that a radiator heat radiation amount (14) radiated from a radiator on a radiator-side cooling water channel is larger than a heater core heat radiation amount (12) radiated from a heater core on a heater core-side cooling water channel, and that a difference between the radiator heat radiation amount and the heater core heat radiation amount is equal to or more than a predetermined value A. Based on a temperature of engine cooling water detected by a temperature sensor positioned in the vicinity of an outlet of an in-engine cooling water channel, it is possible to detect the open failure of the thermostat relatively easily with certainty.

An abnormality diagnosis device of a thermostat includes: a temperature detection module that detects a temperature of cooling water on the basis of a sensor signal of a cooling water temperature sensor; an abnormality determination module that detects an abnormality of the thermostat, when the temperature of the cooling water reaches a first reference temperature and thereafter becomes lower than an abnormality determination reference temperature that is lower than the first reference temperature; and a cooling water temperature adjustment module that executes a control for preventing temperature decrease of the cooling water, when the temperature of the cooling water reaches the first reference temperature and thereafter becomes lower than a second reference temperature that is lower than the first reference temperature and is higher than the abnormality determination reference temperature.

A vehicle includes: a radiator that cools cooling water; a grille shutter that is provided on a vehicle front side of the radiator and opens or closes a grille provided in a vehicle; a first flow path in which the cooling water passes through the radiator; a second flow path in which the cooling water does not pass through the radiator; a thermostat that switches a path between the first flow path and the second flow path; and a failure determiner that performs failure determination of the thermostat based on an actual temperature of the cooling water and an estimated temperature of the cooling water, the estimated temperature being calculated based on a temperature change of the cooling water caused by an open or close state of the grille shutter.

A thermostat misdiagnosis prevention method applied to an engine system of the present disclosure applies high speed/high load and low speed/low load, which are divided by a vehicle speed and an engine output detected from the engine system at an engine warm-up temperature of engine coolant, as monitoring conditions of a thermostat, and determines thermostat fail by primarily determining the thermostat fail with the engine coolant temperature of the engine coolant temperature and the outside air temperature detected from the engine system, then confirming a delay time with respect to the outside air temperature, and secondarily determining the thermostat fail with the engine coolant temperature in a monitoring ECU, thereby corresponding to the enhanced OBD together with preventing the misdiagnosis of the thermostat by the fail-safe according to the primary and secondary determinations.

Systems and methods are disclosed for determining a temperature of a coolant in a cooling system for an engine and diagnosing a thermostat in the engine responsive to the determined temperature. A system includes a liquid cooling system including a thermostat, the liquid cooling system structured to circulate a coolant, and a controller coupled to the liquid cooling system and the EGR system. The controller is structured to: receive engine heat data indicative of a first amount of heat introduced into an engine; receive heat loss data indicative of an amount of heat loss experienced by the coolant; determine a temperature of the coolant based on the first amount of heat and the amount of heat loss; compare the determined temperature of the coolant to a sensed temperature of the coolant; and determine a status of the thermostat responsive to the comparison.

A passive diverter fitting for a cooling system of an engine includes a base defining an interior cavity, an inlet opening extending through the base that is in fluid communication with the interior cavity, an outlet opening that is in fluid communication with the interior cavity, and a bypass opening that is in fluid communication with the interior cavity. The base is configured to be removably disposed in a cavity of an engine block. The inlet opening is positioned to receive coolant when the passive diverter fitting is disposed in the cavity of the engine block. The outlet opening is in fluid communication with the area exterior to the engine block when the passive diverter fitting is disposed in the cavity of the engine block. The bypass opening is in fluid communication with an interior coolant passage of the engine block when the passive diverter fitting is disposed in the cavity of the engine block.

Fluid temperature regulator includes a unitarily-formed housing having an inlet, outlet, bypass outlet, and plurality of valve chamber openings, in line with respective valve chambers. Valve holders are removably disposed within valve chamber openings to position thermostatic valves within the valve chambers. Each valve holder includes at least one wall having at least one holder outlet opening and holder bypass outlet opening. First and second regulator flowpaths through the regulator are defined through the regulator inlet to either the regulator bypass outlet or regulator outlet depending upon whether the thermostatic valves are disposed in a first or second configuration, respectively.