How to Fix an Antifreeze Leak

An antifreeze leak can happen at any point within the car's cooling system. You can usually spot an antifreeze leak while it drips, sprays, or spurts from the leaking part. It's also easy to identify antifreeze by its unique color [source: AA1Car].

To fix an antifreeze leak, you'll need the following items:


  • Duct tape or wrap seal
  • Ground black pepper
  • A large, clean cardboard box
  • Radiator sealant
  • Razor blade

First let's find that leak:

  1. Park the car on a level surface.
  2. Open and flatten the cardboard box, and place it on the ground beneath the front of the car. Leave it there overnight.
  3. Inspect the cardboard in the morning for any drips to determine the approximate location of the leak.
  4. Open the hood and look in the area corresponding to the drips for signs of the leak.
  5. Feel around the hose and hose clamps for signs of wetness.

If the leak is from the radiator, do the following:

  1. See if the radiator has a set of side tanks. If it does, tap or scratch a side tank to determine if it's made of metal. If it's plastic, the next step is a temporary fix; you'll have to buy a new radiator as soon as possible.
  2. Open the radiator cap and pour in radiator sealant. If you don't have sealant, pour 1 or 2 tablespoons of ground black pepper in the radiator.

If the leak is from a hose clamp:

  1. Loosen the clamp.
  2. Check if the hose end has cuts or tears. If it does, cut away the torn area with a razor blade.
  3. Reattach the hose and tighten the clamp firmly.

If the leak is on the hose itself:

  1. Replace the hose.
  2. Pour in more coolant.
  3. Check to make sure the leak has been fixed [source: 2carpros].