PLUG-CUP 5B1866 - Caterpillar

Above normal coolant temperatures can be caused by many conditions. Check the following items in order to diagnose an engine overheating problem:
Personal injury can result from escaping fluid under pressure.If a pressure indication is shown on the indicator, push the release valve in order to relieve pressure before removing any hose from the radiator.
Coolant
Coolant Level Check the coolant level in the cooling system. If the coolant level is low, air will be allowed to enter the cooling system. Air in the cooling system will reduce the efficiency of the cooling system. When air enters the cooling system, air bubbles form around the internal components of the engine. Air bubbles cause a reduction in the cooling of engine parts. Air bubbles can also cause cavitation of the pump during normal engine operation.Refer to Operation and Maintenance Manual, "Cooling System Coolant Level - Check".
Air Bubbles in the Coolant The purpose of a vent line is for the prevention of the formation of air pockets in the cooling system. The air pockets can form while the cooling system is filled with coolant. Air pockets will also form if the correct coolant level is not maintained. Ensure that any vent lines that are in the system are not plugged or missing.A loose hose clamp can allow air into the cooling system during the cooldown period. Ensure that the hose clamps are in good repair and ensure that the hose clamps are correctly torqued.
Quality of the Antifreeze/Coolant Solution Check the quality of the coolant. The coolant should have the following properties:
Color that is like new coolant
Odor that is like new coolant
Free from dirt, debris, and oilsIf the coolant does not have these properties, drain the cooling system and flush the system with cleaner. Refill the system with the correct mixture of water, antifreeze, and coolant conditioner. Check the radiator for a black substance that has a consistency of petroleum jelly. The contamination may be an indication of an engine that has been overheated continuously. Check for a problem with the vent line to the expansion tank. Ensure that the line is not plugged or kinked.Ensure that the cause of any contamination is investigated and ensure that any problems are corrected.Refer to Operation and Maintenance Manual, "General Coolant Information".
Coolant Conditioner and Antifreeze Concentration Check the concentration of the coolant mixture. The mixture should be approximately 50 percent water and 50 percent antifreeze with 3 to 6 percent coolant conditioner. If the concentration of antifreeze is greater than 50 percent, the ability of the cooling system to dissipate heat is reduced. Ensure that the concentration of antifreeze in the cooling system is correct. If the coolant mixture is incorrect, drain the cooling system and flush the cooling system. Refill the cooling system with the correct mixture of water, antifreeze, and coolant conditioner. Refer to Operation and Maintenance Manual, "General Coolant Information".
Cooling Fan Circuit (If Equipped)
Fan Speed Check the fan drive system. A fan drive system that is not turning at the correct speed can cause