How to Repair Leaking Freeze Plugs

Freeze plugs are found on the side of the engine block, and are there for the purpose of preventing the engine block from cracking when the water that runs around it freezes. Back in the days when cars did not use anti-freeze in their radiators, the water would freeze during winter days, and since water expands when it turns to ice, it could crack the engine block. The freeze plug is there to pop out, in order to relieve this pressure. Leaking freeze plugs should then be replaced, because they lose their effectiveness. Below are the steps to help you repair leaking freeze plugs by yourself.

Tools and Materials:

  • Socket Wrench Set
  • Flat Head Screwdriver
  • Pliers
  • Hammer
  • Emery Cloth
  • Gasket Sealer
  • New Replacement Freeze Plug

Step 1: Preparation

Park the car and turn off the engine. Let the car cool before starting the project. Open the hood, and try to locate the freeze plug. It is usually found at the side of the engine or hidden behind the intake manifold. If so, you may have to remove that part first, in order to access the plug.

Step 2: Removing the Freeze Plug

Once you’ve located the plug, get your screwdriver and hammer. Position the screwdriver on the top portion of the plug, and hit it gently with the hammer. This will cause 1 side of the plug to be pushed into the engine. This angles the bottom of the plug away from the engine, making it easier for you to pull it out. Get your pliers, and grab the freeze plug and gently pull it out.

Step 3: Clean the Hole

Get the emery cloth, and clean the hole of any dirt and corrosion buildup. Clean the hole thoroughly, because dirt could be the source of rust, which could eat away areas of your engine and cause larger problems. This area is more susceptible to rust and corrosion, because it connects to the pipes where the water in the radiator runs.

Step 4: Add Sealant

Get your gasket sealant and apply some on the outer portion of the new freeze plug. Make sure to spread it evenly along the sides of the plug, and avoid missing any sections. Spread it across the sides with your finger if you have to. It’s a pretty small plug, so you won’t have a problem coating it fully.

Step 5: Replacing the Plug

Line up the plug against the hole, and place a socket over it. Hit the socket with a hammer and the plug should go right in. If it does not, put the socket over the plug again and keep hitting it gently with the hammer, but don’t overdo it. You might risk damaging the plug.

Step 6: Finishing

Check that the plug is flush against the wall where the hole is. Make sure that the hole is sealed completely by the plug, and that there are no gaps. Get some coolant, and refill the radiator to its recommended level. Start your car, and check the freeze plug, to see if there are any more leaks.