921503-0408 Tohatsu SCREW

Recommended Repairs
Check for High Ambient Temperature and/or for High Inlet Air Temperature
Determine if the ambient air temperature is within the design specifications for the cooling system.Check for high inlet air temperature. Refer to Troubleshooting, "Inlet Air Temperature (High)".Determine the cause of the high air temperature. Make corrections, when possible.Check for a Low Coolant Level and/or for Coolant Leakage
Note: Low coolant level can be the effect of overheating rather than the cause.Check the coolant level.Run the engine to operating temperature. Inspect the cooling system for leaks.Determine whether the leak occurs before the engine overheats.Add coolant, if necessary. If leaking is found, make the necessary repairs.Check for Insufficient Flow of Air and of Coolant Through the Radiator or Heat Exchanger
Radiator
Check the fins of the radiator for obstructions. Check the fan for proper operation.If the radiator fins are obstructed, clean the fins. If the fan does not operate properly, make the necessary repairs.Heat Exchanger
Check for sufficient flow and temperature of the cooling water through the heat exchanger. If the flow of cooling water through the heat exchanger is insufficient, determine the location of the obstruction. If the temperature of the cooling water is too high, determine the cause. Make the necessary repairs.Check the Water Temperature Regulators
Check the water temperature regulators for proper operation. Refer to Systems Operation/Testing and Adjusting, "Testing the Cooling System".Replace the water temperature regulators, if necessary.Check the Coolant Temperature Sensor and/or the Circuit
Check the reading of the coolant temperature on the Caterpillar Electronic Technician (ET). The temperature should rise steadily as the engine is warmed. Ensure that the temperature is reasonable.If the reading on Cat ET for the coolant temperature is not reasonable, troubleshoot the circuit and the coolant temperature sensor. Refer to Troubleshooting, "Analog Sensor Signal".Check the Flow of Coolant Through the Engine
During normal operation, check the status of the following components:
Switch for the inlet pressure of the jacket water
Sensor for the outlet pressure of the jacket water If the flow of coolant through the engine is not sufficient, determine the cause of the obstruction. Make necessary repairs.Check the Exhaust Restriction
Check the back pressure of the exhaust system. Refer to Systems Operation/Testing and Adjusting, "Restriction of Air Inlet and Exhaust".If the back pressure exceeds the specifications for the engine, determine the cause of the excessive back pressure. Make the necessary repairs.Excessive Load
Make sure that the load is not excessive. Reduce the load. If necessary, disengage the driven equipment and test the engine.Check the Base Timing
Verify that the base timing is correct. Refer to Systems Operation/Testing and Adjusting, "Ignition Timing - Adjust".Air/Fuel Ratio
An air/fuel mixture that is too rich will cause overheating. Verify that the exhaust emissions are correct. Refer to Systems Operation/Testing and Adjusting, "Air/Fuel Ratio Control - Adjust".A change in the fuel energy content will change the air/fuel ratio. Obtain a fuel analysis.The fuel supply pressure must be adequate and stable.Strike the gas pressure regulator with a soft hammer. If the engine speed changes, inspect the internal parts of the gas pressure regulator for wear. Inspect the gas pressure regulator's diaphragm for leaks. Make sure that the valve moves freely. The valve must seat correctly.Ensure that the fuel metering valve is operating correctly.