CYLINDER HEAD GP 0R2549 - Caterpillar

This engine has a pressure type cooling system. A pressure type 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 that may be produced by the water pump. Cavitation is the formation of low pressure bubbles in liquids. The low pressure bubbles are produced by mechanical forces. The design of this cooling system reduces the possibility of the formation of air pockets in the system.
Illustration 1 g00921815
Effects of pressure on a cooling systemTemperature and pressure are complementary in a pressure type cooling system. 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 altitude on the boiling point of a water.
Personal injury can result from hot coolant, steam and alkali.At operating temperature, engine coolant is hot and under pressure. The heat exchanger and all lines to heaters or the engine contain hot coolant or steam. Any contact can cause severe burns.Remove the filler cap slowly to relieve pressure only when the engine is stopped and the filler cap for the heat exchanger 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 test the cooling system. The engine must be cold and the engine must not be running. While the engine is cool, slowly loosen the pressure cap in order to relieve the cooling system pressure. 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 Cooling System Testing
Table 1
Required Tools    
Part
Number    Part Description    Qty    
4C-6500     Digital Thermometer     1    
9U-7400     Multitach Tool Group     1    
9S-8140         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.
The connection of any electrical equipment and the disconnection of any electrical equipment may cause an explosion hazard which may result in injury or death. Do not connect any electrical equipment or disconnect any electrical equipment in an explosive atmosphere.
Illustration 2 g00876179
4C-6500 Digital Thermometer The 4C-6500 Digital Thermometer is used in the diagnosis of overheating conditions and in the diagnosis of overcooling conditions. This tool can be used to check temperatures in several different parts of the cooling system. Refer to Operating Manual,