Due to the excessive extremes that a radiator goes through, they can often develop cracks in the material. Ranging from cool fluid to extremely hot, the radiator material frequently expands and contracts. When the coolant goes above the normal operating temperature because of a damaged part or holes in the hose, the excessive heat can make the radiator casing become brittle and create a situation that can allow cracking or breakage, especially around the corners and seams of a radiator. When this happens, there are easy ways to seal the cracked radiator and keep it operating properly for you.
Inspect the radiator and determine where the crack or damage is to the radiator and how big the repair will be. Let the radiator cool off before attempting to seal the cracks and then remove the cap from the top of the radiator. Locate the drain cock on the bottom of the radiator and place a drain pan directly underneath.
Open the drain valve with a set of pliers and allow the coolant to completely drain from the radiator. Be careful not to damage the drain cock when you are turning the valve with the pliers.
Mix some JB Weld paste together in a plastic container with a popsicle stick and apply the paste to the outside of the radiator over the crack. Apply the paste liberally and smooth out about an inch beyond the crack. Allow the paste enough time to dry.
Fill the radiator with coolant and add a bottle of stop leak to the fluid. When the radiator is full, place the cap back on the radiator.
Start the engine of your vehicle and allow it to run for about 10 minutes.
Turn the engine off and check the radiator to verify that the cracks are no longer leaking.
