How to repair a cracked engine block with epoxy

Updated April 17, 2017

A crack in an engine block can cause major damage to the entire engine. Getting the small cracks in the engine block repaired professionally can prove to be expensive. Automotive epoxy putty suitable for car or marine engines is effective in repairing small engine block cracks. Seek professional help for repairing larger cracks that require rebuilding or welding.

Allow your car to cool down completely.

Wear gloves to protect your hands.

Refer to the manual of your car. Locate the engine block and the crack in the engine block.

Roughen the area around the crack using sandpaper.

Take two equal lengths of the two coloured tubes of epoxy resin that come with the pack. Mix the two lengths together to form putty. Keep mixing till they become a single colour.

Apply the epoxy putty on the crack with your fingers till it covers at least 1 inch around the entire crack.

Rub the sandpaper over the putty to make it smooth over the crack and make sure it does not protrude.

Leave the epoxy to dry for 24 hours before turning on the car engine.


Never work near the car engine block when the engine is hot. A hot car engine may cause burns. Wear rubber gloves to work with epoxy putty because the chemicals could cause skin irritation. Epoxy is a sticky compound. Make sure you wash your gloves thoroughly immediately after use. Keep epoxy out of reach of young children.

Things You'll Need

  • Gloves
  • Car manual
  • Sand paper
  • Automotive or metal epoxy
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About the Author

Leanne Clute started writing in 2009 with her work published in several magazines, including "All About Golf," "All About Snow," "All About Bikes," "All About Four Wheels" and "All About Outdoors." She holds an Associate of Science in mortuary science through Hudson Valley Community College, where she is also pursuing a Bachelor of Business in business management.