System Pressure Test

WARNING: Never remove the radiator cap under any conditions while the engine is operating. Failure to follow these instructions could result in damage to the cooling system or engine and/or personal injury. To avoid having scalding hot coolant or steam blow out of the radiator, use extreme care when removing the cap from a hot radiator. Wait until the engine has cooled, then wrap a thick cloth around the radiator cap and turn it slowly to the first stop. Step back while the pressure is released from the cooling system. When you are sure all the pressure has been released, press down on the cap (still with a cloth), turn and remove it.

1. Shut the engine off.
2. Adjust the radiator coolant (fill or drain) to 25 mm (one inch) below the filler neck opening before testing. Wipe clean and wet the rubber sealing surface of the cap before installing the cap tightly on the radiator.
3. Disconnect the electrical connector from the coolant temperature sending unit and remove the temperature sending unit from the engine.

NOTE: With the radiator cap installed and the cooling system pressure relieved, only a small amount of coolant will be lost when the sending unit is removed.

Pressure Test Pump And Attachments:

4. Install the adapter fitting from Rotunda Cooling System Pressurization Kit 021-00012 or equivalent (male thread on one end, and a hose connector on the other end to accommodate the tester hose) tightly into the intake manifold or cylinder head in place of the sending unit.
5. Remove the radiator overflow hose from the overflow nipple. Install a separate hose firmly on the overflow nipple. Insert the free end of separate hose into container of water.
6. Attach the pressure pump and gauge to the adapter-fitting and pressurize the cooling system to the cap LOWER LIMIT (10 psi).
7. No bubbles should appear in the water container when the system is pressurized to the LOWER LIMIT (10 psi). If the system is satisfactory at the lower limit (10 psi), gradually increase the system pressure until a slight stream of bubbles appears in the water container. This is the upper limit of the pressure cap.

NOTE: Replace any radiator cap that exceeds the specified UPPER LIMIT pressure without discharging bubbles (14-16 psi).

8. If the radiator cap does not hold pressure, remove and wash the cap in clean water to dislodge all foreign particles from the gaskets. Check the sealing surface in the radiator filler neck. Inspect the cam lock flanges on both sides of the filler neck for maximum cap engagement.
9. Pressurize the cooling system as outlined in Step 7 (using a radiator cap that operates within the specified upper and lower pressure limits) and observe the gauge reading for approximately two minutes. Pressure should be held between 69 and 89 kPa (10 and 13 psi) and should not drop during this time.
10. If the pressure drops, check for leaks at the engine-to-heater core hoses, engine-to-radiator hoses, bypass hose, water valve hose (if applicable), thermostat housing gasket, radiator and heater core, etc. Also refer to engine system checks if a leak cannot be located in the cooling system. Any leaks which are found must be corrected and the system checked again.
11. If the system holds pressure proceed to Step 12.
12. Release the system pressure by loosening the radiator cap and removing the adapter. Install the temperature sending unit, check coolant level and replenish, if necessary, with the correct coolant solution.