RETAINER 3H6249 - 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 forming of low pressure bubbles in liquids that are caused by mechanical forces. A pressure type cooling system helps to prevent pockets of air from forming.
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Effects of pressure on boiling point of a cooling system
Temperature and pressure work together. When a diagnosis is made of a cooling system problem, both temperature and pressure must be checked. Cooling system pressure will have an effect on the cooling system temperature. For an example, refer to 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.
Personal injury can result from hot coolant, steam and alkali.At operating temperature, engine coolant is hot and under pressure. The radiator and all lines to heaters or the engine contain hot coolant or steam. Any contact can cause severe burns.Remove filler cap slowly to relieve pressure only when engine is stopped and radiator cap is cool enough to touch with your bare hand.Cooling System Conditioner contains alkali. Avoid contact with skin and eyes.
The coolant must be to the correct level in order to check the coolant system. The engine must be cold and the engine must not be running.Slowly loosen the pressure cap in order to relieve the pressure out of the cooling system. Then remove the pressure cap.The level of the coolant should not be more than 13 mm (0.5 inch) from the bottom of the filler pipe. If the cooling system is equipped with a sight glass, the coolant should be to the proper level in the sight glass.Tools for Testing the Cooling System
Table 1
Tools Needed
Part Number Part Name Quantity
4C-6500 Digital Thermometer 1
8T-2700 Blowby/Air Flow Indicator 1
9S-8140 Pressurizing Pump 1
9U-7400 Multitach Tool Group 1
245-5829 Coolant/Battery Tester Gp 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 for the diagnosis of overheating conditions and for the diagnosis of overcooling conditions. This group can be used to check temperatures in several different parts of the cooling system. Refer to the tool's Operating Manual for the testing procedures.
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8T-2700 Blowby/Air Flow Indicator
The 8T-2700 Blowby/Air Flow Indicator is used to check the air flow through the radiator core. Refer to Special Instruction, SEHS8712, "Using the 8T-2700 Blowby/Air Flow Indicator" for the test procedure for checking the blowby of a cooling system's radiator.
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9U-7400 Multitach
The 9U-7400 Multitach Tool Group is used to check the fan speed for an engine. Refer to the tool's Operating Manual for the testing procedure.
Illustration