How to Repair Auto Radiator Punctures

by Darryl James
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Any radiator -- old or new -- is subject to punctures from road debris. When the radiator is punctured, coolant will leak, rendering the radiator unable to properly function. The function of the radiator is to move coolant through the cooling system and through the engine, reducing the temperature of the engine so that it will not overheat. But when there is a puncture in the radiator and the coolant leaks, the temperature rises, causing potential damage to the engine and the radiator. The puncture must be repaired, and in many instances, can be repaired at home. The type and location of the leak will dictate the repair method and the ease of the repair.

Step 1

Visually examine the radiator while the engine is on, looking at the surface to locate any punctures. Larger punctures will spew coolant, while smaller punctures will drip or weep coolant. Spray the surface of the radiator with a water hose or high pressured air to remove any road debris that may be obscuring the leak, including a rock or other debris that may still be lodged in the radiator. Removing surface debris may also increase the size of the leak, but is necessary before repairing the puncture.

Step 2

Turn off the vehicle so that the radiator can cool down. Open the radiator, and pour a bottle or can of cooling system sealant directly into the radiator. Cooling system sealant, commercially available under such names as "Stop Leak," or "Bar's Leaks," comes in powder and pellet form. Both types work the same way, filling the leak and swelling to create a seal for small punctures. Make certain to replace any coolant that the puncture has allowed to escape. Replace the radiator cap, and drive the vehicle for about 30 minutes.

Step 3

Drain the radiator to repair large punctures. Sand the area of conspicuous punctures that are easy to reach by hand. For punctures that are not very easy to reach, drain and remove the radiator, disconnecting the hoses. Seal the puncture with a "cold weld" method, which is simply plugging the leak with a commercial epoxy, effectively sealing the radiator without heat. The cold weld process requires about two hours to properly set before the radiator is ready for use.

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