How do I Change Freeze Plugs in a 289 Ford Mustang?

by John Stevens J.D.
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The 289 small-block V8 engine was available in Ford's Mustang line until the middle of the 1968 production year. If the coolant inside the engine freezes, it will expand. In extreme cases, this expansion will crack the engine block. To avoid this possibility, the 289 was equipped with bronze disks called freeze plugs. The frozen coolant will push the freeze plugs out of the engine block, thereby releasing the pressure from the expansion of the coolant. Sometimes these plugs can corrode and leak, in which case they must be replaced.

Step 1

Raise the Mustang's hood to access the freeze plugs. There are three freeze plugs on each side of the engine block, just below the cylinder head. Each freeze plug is approximately 2 inches in diameter, and is either gold or silver in color.

Step 2

Position a metal punch onto one side of the freeze plug.

Step 3

Tap on the end of the punch with a hammer gently until the opposite side of the freeze plug swivels out of the engine block.

Step 4

Grasp the freeze plug with a pair of pliers, then pull the freeze plug out of the engine block.

Step 5

Apply engine assembly sealant to the outer edges of the new freeze plug.

Step 6

Position the new freeze plug against the opening on the side of the engine block.

Step 7

Insert a large socket into the recessed center of the freeze plug.

Step 8

Tap on the center of the socket with a hammer to drive the freeze plug into the engine block until the lip of the freeze plug is slightly recessed into the engine block.

Step 9

Repeat the process for the remaining freeze plugs.

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