- The pressure type cooling system can operate safely at a higher temperature than the boiling point of water at a range of atmospheric pressures.
- The pressure type cooling system prevents cavitation in the water pump.
Cavitation is the sudden generation of low pressure bubbles in liquids by mechanical forces. The generation of an air or steam pocket is more difficult in a pressure type cooling system.
Regular inspections of the cooling system should be made in order to identify problems before damage can occur. Visually inspect the cooling system before tests are made with the test equipment.
Remember 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 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.
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| Illustration 1 | g00313203 |
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Cooling system pressure at specific altitudes and boiling points of water | |
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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 level 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.
After the engine is cool, 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
Test Tools For The Cooling System
| Required Tools | ||
|---|---|---|
| Part Number | Part Name | Qty |
| 4C-6500 | Digital Thermometer | 1 |
| 9S-8140 | Pressurizing Pump | 1 |
| 1U-7297 | Coolant/Battery Tester | 1 |
| 1U-7298 | Coolant/Battery Tester | 1 |
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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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| Illustration 2 | g00300241 |
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4C-6500 Digital Thermometer | |
The 4C-6500 Digital Thermometer is used in the diagnosis of problems that cause overheating or overcooling in the engine. This tool can be used to check the temperature in several areas of the cooling system. The testing procedure is in Tool Operating Manual, NEHS0554.
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| Illustration 3 | g00286369 |
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9S-8140 Pressurizing Pump | |
The 9S-8140 Pressurizing Pump is used to test the filler caps. This pressurizing pump is also used to pressure test the cooling system for leaks.
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| Illustration 4 | g00439083 |
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1U-7297 Coolant/Battery Tester or 1U-7298 Coolant/Battery Tester | |
Check the coolant frequently in cold weather for the proper glycol concentration. Use either the 1U-7297 Coolant/Battery Tester or the 1U-7298 Coolant/Battery Tester in order to ensure adequate freeze protection. The testers are identical except for the temperature scale. The testers give immediate, accurate readings. The testers can be used for antifreeze/coolants that contain ethylene or propylene glycol.
Making the Correct Antifreeze Mixtures
Do not add pure antifreeze to the cooling system in order to adjust the concentration of antifreeze. The pure antifreeze increases the concentration of antifreeze in the cooling system. The increased concentration increases the concentration of dissolved solids and undissolved chemical inhibitors in the cooling system.
Add an antifreeze and water mixture in the concentration which provides the desired freeze protection. Use the following chart in order to determine the correct concentration of antifreeze in water to use.
| Antifreeze Concentrations For Freeze Protection | |
|---|---|
| Temperature | Concentration |
| Protection to |
30% antifreeze and 70% water |
| Protection to |
40% antifreeze and 60% water |
| Protection to |
50% antifreeze and 50% water |
| Protection to |
60% antifreeze and 40% water |
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Supplemental cooling system additive contains alkali. To prevent personal injury, do not drink, avoid contact with the skin and eyes. |
| NOTICE |
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All water is corrosive at engine operating temperature. The cooling system should be protected with a 3% to 6% concentration of cooling system conditioner at all times. Caterpillar does not recommend the use of cooling system solutions that are intended to stop leaks. Use of these products may result in excessive internal deposits that could reduce the engine's heat transfer characteristics. |
Caterpillar Cooling System Conditioner can be used with an antifreeze or without an antifreeze of ethylene glycol base in the coolant.
When the conditioner is added to the coolant, the cooling system must be flushed and the cooling system must be cleaned.