LINK AS- 5629001 - Caterpillar

One cause for a pressure loss in the cooling system can be a damaged seal on the radiator filler cap.
Illustration 6 g01096114
Cutaway view of a filler cap and radiator (1) Sealing surface of both filler cap and radiator
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.
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. Slowly release the pressure from the cooling system. Then, remove the filler cap.Carefully inspect the filler cap. Look for any damage to the seals and to the sealing surface. Inspect the following components for any foreign substances:
Filler cap
Seal
Surface for sealRemove any deposits that are found on these items, and remove any material that is found on these items.
Install the filler cap on the 9S-8140 Pressurizing Pump .
Look at the gauge for the exact pressure that opens the filler cap.
Compare the gauge reading with the opening pressure that is listed on the filler cap.
If the filler cap is damaged, replace the filler cap.Test the Radiator and the Cooling System for Leaks
Table 3
Tools Needed