Cooling System Checking Fan Belt and Tension Fan belt and belt tension should be checked daily or before each use. Fan belt should not be cracked, damaged, or exhibit excessive wear. Proper tension is 12.7 mm (3/8 - 1/2 in.) belt defl ection per side under 10 lbs. applied tension. If belt is cracked, damaged, or is worn that relocation of pulley shims cannot establish proper belt tension, belt should be replaced. Use only Kohler Part No. 66 203 02-S belt. DO NOT use a substitute belt. For a new belt, assemble lower pulley with all three shims between pulley halves.
For a used/original belt being reinstalled, assemble with two or one shim(s) between pulley halves and remaining shim(s) on outside (front) of outer pulley half. Check belt tension as described above. When proper tension is obtained, individually remove each capscrew of lower pulley, apply Loctite ® 242 ® to threads, and reinstall. Torque each capscrew in a criss- cross sequence to 24.5 N·m (215 in. lb.). Thermostat is mounted in intake manifold, beneath thermostat housing. It controls rapid warm-up and operating temperature of engine. If a problem is encountered which is thought to be fault of thermostat, it can be checked to determine its operating condition.
Before removing and testing thermostat, make sure all other possible causes such as debris accumulation/ obstruction, leaks, belt or fan failure, coolant level, and damaged components are eliminated as possible causes. To Test Remove thermostat from system. Hang or suspend thermostat by its frame in a container of water, so thermostat does not touch bottom of container. Heat water and measure temperature (an oven thermometer can be used). Spring-loaded valve of thermostat should begin to open at 79.4°C (175°F), and can be completely open at 90°C (195°F).
If valve opens at a temperature more than 10 degrees below specifi ed opening or fails to open at a temperature 10 to 15 degrees above specifi ed opening, thermostat should be replaced. If valve in thermostat can be moved or pushed off its seat with a slight effort when thermostat is cold, unit may be considered defective and should be replaced. Thermostat should be replaced if operation is found to be questionable or faulty. Installation 1. Thoroughly clean sealing surfaces of intake manifold and thermostat housing with an aerosol gasket remover. Make sure sealing surfaces are clean and free of nicks or damage. Make sure notch in intake manifold is clean. 2.
Install a new thermostat into intake manifold, so larger spring end is down into well of intake manifold. Position a new thermostat gasket on intake manifold. 3. Install thermostat housing onto intake manifold. 4. Install and torque screws to 9.9 N·m (88 in. lb.). 5. Reconnect radiator hose and secure with hose clamp, if separated previously. Hoses and Tubes Hoses and tubes are used to connect components within cooling system. To guard against coolant loss and hose failure, hoses, tubes and their connections should be checked regularly for leaks or damage. Loss of coolant can result in serious engine damage.
Over time, engine vibration can affect hose/joint connections, and hoses themselves can be affected by heat and coolant. Swelling, hardening, and/or deterioration can occur depending on operating environment. Deterioration usually takes place more rapidly from inside, making outside inspections incomplete and not always dependable. Regular outside inspection and careful inside inspection whenever connections are opened, can minimize a possible in-service problem. Use new clamps whenever a hose is replaced or a joint connection is opened. When making hose connections, a light coating of rubber lubricant will make assembly easier.
High Temperature Sensor A high temperature sensor may be mounted in intake manifold and is used to activate a warning light, audible alarm, or kill engine (depending on application), if safe operating temperature is exceeded. Sensor is a normally open switch which completes a circuit, when coolant temperature reaches rated temperature limit of switch. For these engines temperature sensor limit is 123.8°C (255°F). If warning device activates, or engine kills, indicating an excessive operating temperature, check following: 1. Make sure fan belt is in good condition and properly tensioned. 2. Make sure cooling fan is properly secured, not broken, damaged, or missing blades. 3.
Make sure all air intake and cooling surfaces are clean and free of debris accumulation. 4. After engine has suffi ciently cooled, check coolant level in system to make sure it is not low, or improperly mixed. 5. Check cooling system for leaks. Thermostat Testing and Servicing Temperature Sensor Details 40 66 690 01 Rev. C KohlerEngines.com A A Temperature Sensor