3208 – Checking Pressure Cap

One cause for a pressure loss in the cooling system can be a devective seal on the radiator pressure cap.

After the engine is cool, loosen the pressure cap and let the pressure out of the cooling system. Then remove the pressure cap.


Typical Schematic Of Pressure Cap
(A) Sealing surface of cap and radiator.

Inspect the pressure cap carefully. Look for damage to the seal or to the surface that seals. Any foreign material or deposits on the cap, seal or surface that seals, must be removed.

The 9S8140 Cooling System Pressurizing Pump Group is used to test pressure caps and to pressure check the cooling system for leaks.

1. After the engine is cool, loosen the pressure cap to the first stop and let the pressure out of the cooling system. Then remove the pressure cap.

2. Put the pressure cap on the 9S8140 Cooling System Pressurizing Pump Group.


9S8140 Cooling System Pressurizing Pump Group

3. Look at the gauge for the exact pressure that makes the pressure cap open.

4. Make a comparison of the reading on the gauge with the correct pressure at which the pressure cap must open.

NOTE: The correct pressure that makes the pressure cap open is on the pressure cap and is also in the Specifications.

5. If the pressure cap is defective, install a new pressure cap.

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