COUPLING 1242114 - Caterpillar

This engine has a pressure type cooling system. A pressure type cooling system has two advantages. The cooling system can be operated in a safe manner at a temperature higher than the normal boiling point (steam) of water. This type of system prevents cavitation in the water pump. Cavitation is the sudden formation and the collapse of low pressure bubbles in liquids by mechanical forces. With this type of cooling system, an air pocket or a steam pocket becomes more difficult to create in the cooling system.Visual Inspection Of The Cooling System
Cooling systems that are not regularly inspected are the cause for increased engine temperatures. Make a visual inspection of the cooling system before a test is made with test equipment.
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.
Look for leaks in the system.
Make sure that air flow through the radiator does not have a restriction. Look for bent core fins between the folded cores of the radiator. Also, look for trash between the folded cores of the radiator.
Inspect the drive belts for the fan.
Check for damage to the fan blades.
Look for air or combustion gas in the cooling system.
Inspect the filler cap, and check the surface that seals the filler cap. This surface must be clean.Testing The Cooling System
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Boiling point of waterRemember that temperature and pressure work together. When a diagnosis is made of a cooling system problem, temperature and pressure must be checked. Cooling system pressure will have an effect on the cooling system temperature. For an example, refer to the Illustration 1. This will show the effect of pressure on the boiling point (steam) of water. This will also show the effect of height above sea level. Test Tools For Cooling System
Table 1
Tools Needed     Quantity    
4C-6500     Digital Thermometer     1    
8T-2700     Blowby/Air Flow Indicator Group     1    
9S-8140     Pressurizing Pump     1    
6V-3121     Multitach     1    
Making contact with a running engine can cause burns from hot parts and can cause injury from rotating parts.When working on an engine that is running, avoid contact with hot parts and rotating parts.
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4C-6500 Digital Thermometer The 4C-6500 Digital Thermometer is used in the diagnosis of overheating problems or in the diagnosis of overcooling problems. This group can be used to check temperatures in several different parts of the cooling system. Refer to the testing procedure in Operation and Maintenance Manual, SEBU6945.
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8T-2700 Blowby/Air Flow Indicator Group The 8T-2700 Blowby/Air Flow Indicator Group is used to check the air flow through the radiator core. Refer to the testing procedure in Special Instruction, SEHS8712.
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9U-7400 Multitach The 9U-7400 Multitach is used to check the fan speed. Refer to the testing procedure in Special Instruction, SEHS7807.Checking the Filler Cap
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9S-8140 Pressurizing Pump The 9S-8140