How Does Radiator Sealant Work?

Updated April 17, 2017

If your vehicle's radiator is leaking, a radiator sealant may help you stop the leak. Sealants will not work on large cracks or cracks in the radiator seams, but they can plug smaller cracks and holes.


There are two types of radiator sealants: liquid and powder. Both work the same way. Sealants contain tiny particles that literally stick into the crack or hole. Most radiator sealants will work on a variety of materials including plastic, cast iron and aluminium.


Once they adhere to the hole or crack in your radiator, the particles in the coolant shrink slightly. On an external leak, the particles flow to the point of the leak, collect on the outside of the seepage and accumulate inward. For internal leaks, heat causes the particles to melt and seal head gasket leaks or small cracks. The particles also will fill pores in aluminium or cast iron, preventing leakage of coolant into oil in the crankcase.


Although there are different formulas for radiator sealants, they generally contain ingredients like soda ash, nut shells, turmeric and ginger rhizomes. Sealants are flammable and you should not store them near sources of heat.

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About the Author

Gail Dudley began writing in 1984, with her articles appearing in "Arizona Highways," "Phoenix Home & Garden," "Conde Nast Traveler," "The Washington Post" and "The Business Journal." Her short story, "Silky," is included in the anthology, "Good Dogs Doing Good." She earned her Master of Arts in English writing from Hollins University and completed additional graduate studies at the University of London.