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| Illustration 1 | g00286266 |
Effects of pressure on a cooling system | |
Temperature 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.
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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 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. |
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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
| Required Tools | ||
|---|---|---|
| Part Number |
Part Description | Qty |
| 4C-6500 | Digital Thermometer | 1 |
| 9S-8140 | Pressurizing Pump | 1 |
| 9U-7400 | Multitach Tool Group | 1 |
| 1U-7297 | 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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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. |
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| Illustration 2 | g00313246 |
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, NEHS0554, " 4C-6500 Digital Thermometer Group" for the testing procedure.
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| Illustration 3 | g00286276 |
9U-7400 Multitach | |
The 9U-7400 Multitach Tool Group is used to check the fan speed. Refer to Operating Manual, NEHS0605, " 9U-7400 Multitach Tool Group " for the testing procedure.
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| Illustration 4 | g00286369 |
9S-8140 Pressurizing Pump | |
The 9S-8140 Pressurizing Pump is used to test the cooling system's pressure cap. This pressurizing pump is also used to pressure test the cooling system for leaks.
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| Illustration 5 | g00439083 |
1U-7297 Coolant/Battery Tester | |
Check the coolant frequently in cold weather for the proper glycol concentration. Use the 1U-7297 Coolant/Battery Tester in order to ensure adequate freeze protection. The tester gives immediate, accurate readings. The tester can be used to test antifreeze/coolants that contain ethylene glycol or propylene glycol.
Making the Correct Antifreeze Mixtures
Adding pure antifreeze as a makeup solution for the cooling system top-off is an unacceptable practice. Adding pure antifreeze increases the concentration of antifreeze in the cooling system. This increases the concentration of the dissolved solids and the undissolved chemical inhibitors in the cooling system. Add the antifreeze and water mixture in the same concentration as your cooling system. Refer to Operation and Maintenance Manual, "General Coolant Information" for determining the correct concentration of antifreeze and water.
Checking the Filler Cap
| Required Tools | ||
|---|---|---|
| Part Number |
Part Description | Qty |
| 9S-8140 | Pressurizing Pump | 1 |
One cause for a pressure loss in the cooling system can be a damaged seal on the pressure cap.
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| Illustration 6 | g01063350 |
Pressure cap diagram (typical example) (1) Sealing surfaces of both the pressure cap and filler neck | |
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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 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. |
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To check for the amount of pressure that opens the pressure cap, use the following procedure:
- After the engine cools, carefully loosen the pressure cap. Slowly allow the pressure from the cooling system to escape. Then, remove the pressure cap from the filler neck.
Carefully inspect the cap. Look for any damage to the seals and to the sealing surface. Inspect the following components for any foreign substances:
- Pressure cap
- Pressure cap's seal
- All sealing surfaces
Remove the formation of any deposits that are found on the seal and sealing surfaces. Thoroughly clean the cap, the seal, and all sealing surfaces.
- Pressure cap
- Install the pressure cap on the 9S-8140 Pressurizing Pump .
- Use the pump to slowly apply pressure to the pressure cap. Record the exact pressure that opens the pressure cap.
- Compare the gauge reading with the opening pressure that is listed on the pressure cap.
- If the pressure cap is damaged, replace the pressure cap.
Testing the Heat Exchanger and Cooling System for Leaks
| Required Tools | ||
| Part Number |
Part Description | Qty |
| 9S-8140 | Pressurizing Pump | 1 |
Use the following procedure in order to check the cooling system for leaks:
- After the engine cools, carefully loosen the pressure cap. Slowly allow the pressure from the cooling system to escape. Then, remove the pressure cap from the filler neck.
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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 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. |
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- Ensure that the coolant is at the proper level.
- Install the 9S-8140 Pressurizing Pump onto the cooling system's filler neck.
- Increase the pressure in the cooling system to 20 kPa (3 psi) above the pressure that is designated on the pressure cap.
- Check the cooling system for external leakage.
- Check all cooling system hoses for leakage. Check the hose's connection points for leakage. Also, check the hoses for swelling. Replace hoses that are damaged or leaking.
If the gauge reading remains steady for five minutes and there is no evidence of outside leakage, the cooling system is not leaking.
If the pressure on the gauge decreases in the five minute interval and no external leakage is observed, there is evidence of leakage that is internal to the engine.
If the pressure on the gauge decreases in the five minute interval and external leakage is observed, external leakage has been confirmed.
Make repairs to the cooling system, as required.
Test for the Water Temperature Gauge
| Required Tools | ||
|---|---|---|
| Part Number |
Part Description | Qty |
| 4C-6500 | Digital Thermometer | 1 |
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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 heat exchanger. |
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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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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. |
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If you suspect the water temperature gauge is providing an inaccurate temperature reading, use the following procedure to check the accuracy of the water temperature indicator.
Note: Caterpillar Electronic Technician (Cat ET) can also be used to read engine temperature.
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| Illustration 7 | g01066470 |
(1) Water manifold assembly | |
Remove a plug from water manifold assembly (1). Install the 4C-6500 Digital Thermometer into the port.
Start the engine. Run the engine until the temperature reaches the desired range according to the test thermometer. The reading on the water temperature indicator should agree with the test thermometer within the tolerance range of the water temperature indicator.