Radiator Cap: Testing and Inspection

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 RADIATOR 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 IT IS CERTAIN ALL THE PRESSURE HAS BEEN RELEASED, PRESS DOWN ON THE RADIATOR CAP (STILL WITH A CLOTH), TURN AND REMOVE.

1. Remove the radiator cap from the radiator filler neck.
2. Use water to clean in area of rubber seal and vacuum relief valve. Immerse radiator cap in water and install radiator cap pressure test adapter from Radiator/Heater Core Pressure Tester on the radiator cap.

NOTE: The filler neck seal is reversible so that it may be used on either end of the radiator cap pressure test adapter.

3. Immerse the filler neck seal in water and install in filler neck adapter. Install the filler neck adapter with the seal on the open end of the radiator cap pressure test adapter.
4. Connect the female quick disconnect fitting of the pressure test pump to the male quick disconnect fitting of the filler neck adapter.
5. Slowly depress the plunger of the pressure test pump until the pressure gauge reading stops increasing, and note highest pressure reading obtained.

NOTE: If the plunger of the pump is depressed too quickly, an erroneous pressure reading will result.

6. Release pressure by turning pressure relief screw counterclockwise. Then tighten pressure relief screw and repeat Step 5 at least twice to ensure pressure test reading is repeatable within acceptable gauge reading limits of radiator cap and is not erratic.
7. If pressure test gauge readings are not within acceptable gauge reading limits, replace radiator cap.