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How to Plug Up Your Radiator Leak With Pepper

by Wade Shaddy

Old school auto repair works. Some emergency repairs are still being used. One of them is the use of black pepper to seal small radiator leaks. When black pepper is introduced into the system, the small particles travel to the leak where they expand and seal the leak. The pepper does not deteriorate and will seal the leak until you can get it fixed by a professional.

Remove the lid from the radiator after the engine cools down.

Pour one tablespoon of black pepper into the radiator. Don't put it in the plastic back-up reservoir, put it directly into the radiator via the radiator cap opening. Fill the radiator up with a 50/50 mix of water and antifreeze. Drive the car for fifteen minutes or until the temperature is at its normal operating level. Shut off the car. Wait another 30 minutes for the particles to swell up.

Open the hood and look around the radiator where it was leaking. Crouch down and look under the car. If you see any signs of leakage, add one more tablespoon of black pepper.

Drive the car normally for about 30 minutes to seal the leak.


  • Course ground black pepper works best, the bigger the particles, the better.


  • Never, ever try to remove the cap from a hot radiator. if the radiator continues to leak, you might have a bad hose, or a leak that requires professional repair.

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About the Author

Specializing in hardwood furniture, trim carpentry, cabinets, home improvement and architectural millwork, Wade Shaddy has worked in homebuilding since 1972. Shaddy has also worked as a newspaper reporter and writer, and as a contributing writer for Bicycling Magazine. Shaddy began publishing in various magazines in 1992, and published a novel, “Dark Canyon,” in 2008.

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