How to Replace a Freeze Plug in a Ford Explorer

by Don Bowman

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No matter how perfectly you engineer a machine, you can't escape certain inevitabilities in nature. One of them is that water tends to expand as it freezes and hardens into ice, and another is that expanding ice is stronger than metal engine blocks. Modern vehicles use antifreeze to keep engine blocks from splitting in twain under the pressure of expanding ice, but just as many still use freeze plugs as a last line of defense against the scourges of nature. Being effectively just press-fit into the block, these plugs can develop leaks over time. But most are easier to replace than you might think, particularly on a big vehicle like the Ford Explorer.

Step 1

Raise and support the vehicle on jack stands. Allow it to cool completely. Carefully remove the radiator cap or reservoir cap and attach the radiator pressure tester; pump it up to 15 pounds. Look under the vehicle for the leaking freeze plug. There are three plugs on each side of the block under the exhaust manifold and two in the rear of the block between the engine and transmission. If the rear freeze plug is leaking, it can be seen by antifreeze leaking out of the bottom of the transmission bell housing. A leaking freeze plug in the rear requires removing the transmission to access the plug.

Step 2

Look under the radiator for the drain petcock valve; it's a plastic piece with a fin on the top. Place a drain pan under it, and turn the petcock valve counterclockwise one-half turn to open it. Allow the cooling system to drain completely; this may take some time, particularly if the cooling system is clogged with junk and debris. Close the petcock tightly when the system is empty.

Step 3

Remove the freeze plug using a common screwdriver and hammer. Place the tip of the screwdriver on one side of the freeze plug and tap the screwdriver with the hammer to push the side of the freeze plug inward. The idea is to push one side in and rotate the other side out. Try not to push the freeze plug into the block. It would still come out, but it would take more work. After the freeze plug has rotated enough, grab the side of the freeze plug with the vise grips and pull it out.

Step 4

Clean the area with a clean cloth. Install the new freeze plug by holding it in place and pushing with the thumbs to start it into the hole. Make sure it is dead-straight going in.

Step 5

Drive the freeze plug into the block—using the 1/2-inch drive socket and extension—and tap it in a little at a time, always checking to make sure that it is going in straight. Tap it in until it is 1/16 inch in from the block.

Step 6

Refill the radiator and once again attach the radiator pressure tester and check for leaks. If you see none, start the engine and allow it to run while you keep the radiator topped up with coolant. Allow the engine to come up to temperature; you'll know it's up to temperature and thermostat is open when the upper radiator hose gets hot. Continue adding coolant until it won't take any more. Install the radiator cap.

Step 7

Top the coolant reservoir up to the "HOT" fill line, and allow the engine to reach full operating temperature. Shut it down. As the engine cools, it will draw coolant in from the reservoir tank. Keep the tank topped up to at least the "COLD" fill line; do not allow it to run dry. Repeat the heating, cooling and topping off cycle. Monitor the coolant level in the tank for the next 100 miles to make sure all the air is out of the system.

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