CAP 9K0805 - Caterpillar

This engine has a pressure type cooling system. This type of cooling system can be operated in a safe manner at a temperature higher than the normal boiling point (steam) of water.A pressure type cooling system helps prevent cavitation in the water pump. Cavitation is the formation of air bubbles in low pressure areas in liquids. The mechanical forces that are created by the pumping action of the water pump are considered to be a common cause of cavitation. A pressure type cooling system tends to inhibit the formation of air bubbles within the cooling system. Air bubbles are the cause of air pockets, or steam pockets, which can damage the cooling system.Visual Inspection Of The Cooling System
Cooling systems that are not regularly inspected and maintained may be the cause of increased engine temperatures. Make a visual inspection of the cooling system before you begin testing.
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.
Check the coolant level in the cooling system. Read the two level indicators for the cooling system that are in the top of the radiator.
Inspect the cooling system for leaks.Note: A small amount of coolant leakage across the surface of the water pump seals is normal. This leakage is required in order to provide lubrication for the water pump seals. A weep hole has been machined in the water pump housing in order to allow this coolant/seal lubricant to drain from the pump housing. Intermittent leakage of small amounts of coolant from this hole is not an indication of water pump seal failure. Do not replace the water pump seals unless you find a continuous flow of coolant, or a large amount of coolant, that is leaking from the water pump housing. Refer to Disassembly and Assembly, "Water Pump" for the replacement procedure of the water pump seals.
Make sure that air flow through the radiator is not restricted. Look for bent core fins between the folded cores of the radiator. Also, look for debris between the folded cores of the radiator.
Inspect the fan drive belts for cracking or separation.
Inspect the fan blades in order to ensure that the blades are not damaged or bent.
Check the engine oil dipstick for signs of an internal coolant leak. The engine oil will have a milky appearance if contamination from the cooling system is present. If internal leakage is suspected, refer to "Testing The Radiator And Cooling System For Leaks" for instructions on pressure testing the cooling system.
Look in the radiator filler neck for air bubbles or combustion gas in the cooling system.
Inspect the pressure cap and the sealing surface. This surface must be clean and free of corrosion.Testing The Cooling System
Illustration 1 g00286266
Boiling point of waterTemperature and pressure work together. When a diagnosis is made of a cooling system problem, both the temperature and the pressure must be checked. Cooling system pressure will have an