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| Illustration 1 | g00286266 |
Atmospheric pressure and the boiling point of water | |
Remember that temperature and pressure work together. To help diagnose a cooling system problem, check the temperature and the pressure. The cooling system pressure has an effect on the cooling system temperature. Illustration 1 demonstrates the effect of pressure on the boiling point (steam) of water.
Testing the Filler Cap
| Tools Needed | Qty | |
| 9S-8140 Pressurizing Pump | 1 | |
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| Illustration 2 | g00286369 |
9S-8140 Pressurizing Pump | |
The 9S-8140 Pressurizing Pump is used to test the cooling system for leaks. The pump can also be used to test the filler cap, the pressure relief valve, and the pressure gauge.
One cause for a pressure loss from the cooling system can be a damaged seal on the filler cap.
To check for the amount of pressure that opens the filler cap, use the following procedure:
- After the engine cools, carefully loosen the filler cap in order to release the pressure from the cooling system. Remove the filler cap.
- Carefully inspect the filler cap. Look for any damage to the seals and to the sealing surface.
Remove any deposits that are found.
If the filler cap is damaged, obtain a new cap.
- Install the filler cap on the 9S-8140 Pressurizing Pump .
The opening pressure for the filler cap's pressure relief valve is stamped on the filler cap.
- Apply pressure to the filler cap. Compare the gauge reading with the opening pressure that is listed on the filler cap.
If the cap cannot sustain the correct pressure, obtain a new cap.
If the filler cap's pressure relief valve does not open within approximately 7 kPa (1 psi) of the pressure that is stamped on the filler cap, obtain a new cap.