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How to Change the Freeze Plug on a 4.3 L Vortec Engine

by David Marsh

Freeze plugs are created when the 4.3-liter Vortec engine is cast. There has to be a way of letting the molten metal flow through the mold. The freeze plug, or freeze plug hole, is a remnant of the casting process. After casting, the auto company puts a plug in the freeze plug hole. The freeze plug offers a way of venting expanding coolant if it freezes. The plug isn't welded in. It can pop out if the frozen, expanding coolant pushes on it.

Place a large pan under the radiator and take out the drain plug with a wrench. Drain the coolant into the pan, then place the pan of coolant to one side. Replace the drain plug.

Hit the side of the old freeze plug with the drift and the hammer. The old plug will swivel in the hole. Take it out with the pliers.

Rub the emery cloth around the inside of the freeze plug hole.

Coat the bearing surface of the new freeze plug with sealant. If the manufacturer of the sealant recommends a waiting period while the sealant sets or cures, wait until that time has passed. Press the new freeze plug into the hole and seat it with gentle blows of the hammer.

Put the sealer head inside the new freeze plug. Drive it further inside the freeze plug hole with the hammer until it's 1/16 of an inch below the surface of the engine block.

Put the coolant back into the radiator and start the engine.

Test the new freeze plug for leaks.


  • Rubber freeze plugs are available but should only be used for emergency repairs. Don't use any sealant on a rubber plug.

Items you will need

About the Author

In 1990 David Marsh began writing a column in the "Idaho Falls Post-Register" titled "Good Things," which presented restaurant reviews, sports analysis and movie criticism. Besides newspaper columns, Marsh researched police procedures for the Federal government. He has a Bachelor of Arts in administration and a Bachelor of Science in journalism from the University of Utah.

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