Pressure Cap Test Cooling System Leak Check To test the cooling system for leaks, use the following procedure: W ARN I N G If the engine has been in operation and the coolant is hot, slowly loosen the pressure cap to the first stop and let the pressure out of the cooling system, then remove the pressure cap. 1 . Remove pressure cap from the radiator. 2 . Make sure the radiator is full (hot) or nearly full (cold) of coolant. 3 . Attach the Cooling System Pressurizing Pump Tool to the radiator filler neck. 4 . Pump the pressure to 20 kPa (3 psi) more than the rated pressure of the cap. 5 . Check the radiator for outside leakage. 6 .
Check all connections and hoses of the cooling system for outside leakage. 7 . If there is no outside leakage and the pressure reading on the gauge is still the same after 5 minutes, the radiator and cooling system do not have leakage. If the reading on the gauge goes down and there is no outside leakage, there is leakage on the inside of the cooling system. Make repairs as necessary. Pressure Cap Diagram (A) Seali ng surface of cap and radiator. One cause for a pressure loss in the cooling system can be a bad seal on the pressure cap of the system. Inspect the pressure cap carefully. Look for damage to the seal or the sealing surface.
Any foreign material or deposits on the cap, seal or seal or sealing surface must be removed. To check the pressure cap opening pressure, do the following procedure. W ARN I N G If the engine has been in operation and the coolant is hot, slowly loosen the pressure cap to the first stop and let the pressure out of the cooling system, then remove the pressure cap. 1 . Remove pressure cap from the radiator. 2 . Put the pressure cap on the Cooling System Pressurizing Pump Tool. 3 . Look at the gauge for the pressure that makes the pressure cap open. It must be as follows: A403658 ............. 76 to 100 kPa (11 to 14.5 psi) 4 . If the pressure cap is bad, install a new pressure cap.
G643 (E) Service Manual Chapter 3. Engine Mechanical System 53