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How to Patch a Radiator Leak With Epoxy

by Michelle Miley

Leaks are not uncommon as automobile radiators age, even if the radiator happens to be in a low-mileage vehicle. Unfortunately, new radiators can be expensive, even if you are able to save money on labor by installing the unit yourself. Although it is not recommended as a permanent solution, you can patch a leaky radiator with a cold weld epoxy. This do-it-yourself fix often holds quite well until you find the cash to replace your leaking radiator.

Step 1

Drain the radiator.

Step 2

Thoroughly clean the radiator around the leak. Failing to do so will prevent the epoxy from adhering.

Step 3

Apply a cold weld epoxy to the radiator. Epoxies vary, so be sure to follow the directions on the epoxy package for prepping and applying the epoxy.

Step 4

Allow the epoxy to cure. This takes about two hours on average but can vary by epoxy.

Step 5

Refill the radiator.

Twist the radiator cap back on loosely. Make sure the cap is on tight enough to stay put but not on as far as it will go. Making the radiator cap too tight will create a strong vacuum that could cause the epoxy patch to fail.

Tip

  • If the leak is the result of a broken radiator tube, you will need to bend the fins with a pair of pliers, fold the broken tube ends over and then epoxy them shut. You will need to take the radiator out of the car to do this.

Warning

  • If the car has been running, shut it off and wait 15 minutes for the engine to cool before attempting a radiator repair.

Items you will need

  • Drain pan
  • Clean rag
  • Cold weld epoxy
  • Coolant
  • Funnel

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