A radiator pressure tester is needed to detect holes in hoses, defective gaskets, weak internal seals, or a faulty heater core that can lead to overheating. By increasing the radiator pressure, these issues can all be found through either visually inspecting for leaks or by smelling for the sweet scent of antifreeze.
Step 1 - Cool the Car
Completely cool the engine. Check the owner’s manual for the correct PSI for the radiator. If you do not have the owner’s manual, check the radiator cap. Fill all coolant levels in both the radiator and the reservoir to the fill line to ensure an accurate pressure reading.
Step 2 - Pressurize
Remove the radiator cap and attach the radiator cap extension of the pressure tester. Pump the pressure gauge up to the directed PSI, and set the pressure tester on a level surface.
Step 3 - Check
Visually check under the car and around the engine for drips or leaks in hoses, caps, and gaskets. Problems with the internal heater core cannot be seen, only smelled. Get into the passenger side, turn on the fan, and smell for sweetness. Lastly, check the pressure tester for pressure loss. These are all signs of radiator problems.