Abstract: Methods of and apparatus for identifying faults in cooling systems of internal combustion engines include a first temperature sensor clamped to the top radiator hose and a second temperature sensor clamped to the bottom radiator hose. The first temperature sensor is connected to a first array of heat switches, each of which has an output indicative of a selected temperature level detected in the first radiator hose. The second sensor is connected to a second array of heat switches, each of which has an output indicative of a selected temperature level in the second radiator hose. Each of the heat switches is connected through a collator to logic circuitry, which logic circuitry also has inputs from a timing circuit. The logic circuitry has outputs which energizes indicators, such as an indicator lamps, when the temperature/time condition of the engine is within selected ranges indicative of selected cooling system faults.

Abstract: Methods of and apparatus for identifying faults in cooling systems of internal combustion engines include a first temperature sensor clamped to the top radiator hose and a second temperature sensor clamped to the bottom radiator hose. The first temperature sensor is connected to a first array of linear amplifiers, each of which has an output indicative of a selected temperature level detected in the first radiator hose. The second sensor is connected to a second array of linear amplifiers, each of which has an output indicative of a selected temperature level in the second radiator hose. Each of the linear amplifiers is connected through a collator to logic circuitry, which logic circuitry also has inputs from a timing circuit. The logic circuitry has outputs which energizes indicators, such as an indicator lamps, when the temperature/time condition of the engine is within selected ranges indicative of selected cooling system faults.

Abstract: An electronic thermostat tester monitors the heat rise of the coolant in the radiator of an internal combustion engine as a function of time and provides "defect" signals if the heat does not reach a preselected level (160.degree. F.) in a predetermined time period (eight minutes). The electronic thermostat tester can also be used with bulldozers, buses, tractors and other heavy-duty equipment. When use with heavy-duty engines, the time intervals will be longer. If the preselected heat range is reached within the time period a light indicates that the thermostat is functioning properly. The tester further includes a plurality of indicating lights for thermostat levels (180.degree. F. and 190.degree. F.) above the preselected heat level (160.degree. F.) for engines having different ratings. By using this thermostat tester one does not have to remove the thermostat from an engine to test the thermostat. In addition, the tester may be used to detect clogged engine blocks, radiators and defective automatic fans.

Abstract: An inlet couples a duct system to a point in the cooling system of a liquid-cooled engine. A liquid differential adjusting device in the duct system adjusts for the type of liquid in the cooling system. A thermometer in the duct system detects and indicates the temperature of the liquid in the system. A pressure gage in the duct system detects and indicates the pressure of the liquid in the system. An outlet couples the duct system to another point in the cooling system of the engine.