Grand Cherokee 4WD V8-4.7L (2003)
Radiator Cap: Testing and Inspection
DIAGNOSIS AND TESTING-RADIATOR PRESSURE CAP
Remove cap from radiator. Be sure that sealing surfaces are clean. Moisten rubber gasket with water and install the cap on pressure tester (tool 7700
or an equivalent) . Operate the tester pump and observe the gauge pointer at its highest point. The cap release pressure should be 124 to 145 kPa (18
to 21 psi). The cap is satisfactory when the pressure holds steady. It is also good if it holds pressure within the 124 to 145 kPa (18 to 21 psi) range for
30 seconds or more. If the pointer drops quickly, replace the cap.
CAUTION: Radiator pressure testing tools are very sensitive to small air leaks, which will not cause cooling system problems. A pressure cap that
does not have a history of coolant loss should not be replaced just because it leaks slowly when tested with this tool. Add water to tool. Turn tool
upside down and recheck pressure cap to confirm that cap needs replacement.
CLEANING
Clean the radiator pressure cap using a mild soap and water only.
INSPECTION
Visually inspect the pressure valve gasket on the cap. Replace cap if the gasket is swollen, torn or worn. Inspect the area around radiator filler neck for
white deposits that indicate a leaking cap.