For the inspection, take out the radiator cap and set up the Radiator Pressure Tool, pump air into the cap and wait for the pressure cap upper gasket to relieve at 124 kPa (18 psi); the minimum pressure the cap can keep is 110 kPa (16 psi). After you remove the pressure tester, place the cap facing up; the vent valve at the bottom will stay shut. Should the gasket be swollen and get in the way of the valve, put on a new cap. Once the cap is clean, upend it; if any light shines through the space between the vent valve and the rubber seal, put on a new cap. Be sure to check the warning that comes with every coolant bottle pressure cap, since it advises opening the cap carefully when the system is cold due to rising pressure in the system, to avoid burns. You should never remove the pressure cap unless you are: checking the freeze point, adding antifreeze, servicing the system, changing the coolant or checking for vacuum leaks. Wait 15 minutes after running the vehicle if you are going to remove the cap. Wrap the cap with a shop towel then rotate the cap in a counterclockwise direction until it stops without pushing down so fluid can run off through the overflow tube. After the system is no longer pumping coolant and steam and pressure goes down, fully remove the cap. You should make sure to squeeze the radiator inlet hose with a shop towel both before and after you turn to your first stop.