B5.9G, B5.9LPG – Troubleshooting and Repair Manual – Coolant Temperature Above Normal – Gradual Overheat

Electronic fault codes active or high counts of inactive fault codes

Refer to Section TF in the Troubleshooting and Repair Manual, Fuel Systems and Electronics, B5.9G, C8.3G, L10G-III, Bulletin 3666118.

Coolant temperature gauge or sensor is malfunctioning

Test the gauge and the sensor. Repair or replace, if necessary. Refer to the OEM service manual.

Cold weather radiator cover or winterfront is closed

Open the cold weather radiator cover or the winterfront. Maintain a minimum of 784 cm² [122 in²] or approximately 28 x 28 cm [11 x 11 in] of opening at all times. Refer to the OEM service manual.

Coolant level is below specification

Inspect the engine and cooling system for external coolant leaks. Repair if necessary. Add coolant. Refer to Procedure 008-018.

Lubricating oil level is above or below specification

Check the oil level. Add or drain oil if necessary. Refer to Procedure 007-025. Check the dipstick calibration.

Coolant mixture of antifreeze and water is not correct

Verify the concentration of antifreeze in the coolant. Add antifreeze or water to correct the concentration. Refer to Procedure 008-018 and the OEM service manual.

Charge air cooler fins, radiator fins, or air conditioner condenser fins are damaged or obstructed with debris

Inspect the charge air cooler, air conditioner condenser, and radiator fins. Clean, if necessary. Refer to Procedures 010-027 and 008-042 and the OEM service manual.

Fan drive belt or water pump belt is loose

Check the belt tension and tighten if necessary. Refer to Procedures 008-002 and 008-003.

Thermostat is not correct or is malfunctioning

Check the thermostat for the correct part number and for correct operation. Refer to Procedure 008-013 and the OEM service manual.

Water pump is malfunctioning

Check the water pump. Replace the water pump if necessary. Refer to Procedure 012-104.

Cooling system hose(s) collapsed, restricted, or leaking

Inspect the cooling system hose(s) for restrictions or obstructions. Refer to Procedure 008-045.

Fill line or vent lines are restricted, obstructed, or not routed correctly

Check the vent lines and the fill line for correct routing and for restriction. Refer to the OEM specifications.

Radiator cap is not correct, is malfunctioning, or has low-pressure rating

Check the radiator pressure cap. Refer to Procedure 008-047 and the OEM service manual.

Intake manifold air temperature is above specification

Check intake air temperature. Refer to Procedure 018-019.

Fan drive or fan controls are malfunctioning

Check the fan drive and controls. Refer to the OEM service manual.

Fan shroud is damaged or missing or the air recirculation baffles are damaged or missing

Inspect the shroud and the recirculation baffles. Repair, replace, or install, if necessary. Refer to Procedure 008-038 and the OEM service manual.

Cooling system is contaminated with dirt, scale, or sludge

Clean the cooling system. Rod the radiator if necessary. Refer to Procedure 008-018.

Coolant is contaminated with lubricating oil

Refer to Procedure 008-018.

Air or combustion gases are entering the cooling system

Check for air or combustion gases in the cooling system. Refer to Procedure 008-019 and the OEM service manual.

Radiator core is internally obstructed or damaged, or the check valve or J-tube is malfunctioning

Inspect the radiator and clean if necessary. Refer to Procedure 008-042 and the OEM service manual.

Torque converter is malfunctioning

Check the torque converter. Refer to the OEM service manual.

Cooling system has insufficient capacity

Refer to Procedure 008-018.

Keyswitch circuit is malfunctioning

Check the vehicle, equipment, or vessel keyswitch circuit. Refer to Procedure 019-064 in the Troubleshooting and Repair Manual, Fuel Systems and Electronics, B5.9G, C8.3G, L10G-III, Bulletin 3666118.

Engine is overfueled

Check the engine fuel rate. Refer to INSITE™ User’s Manual, Bulletin 3885798.