How to Seal an Engine Block With J-B Weld

If your engine block is cracked, you may be able to patch it with J-B Weld.

J-B Weld is a "liquid steel/epoxy resin" that can be used to patch nearly any metal. It has a temperature rating of up to 500 degrees Fahrenheit, so it can safely be used on any automotive component except the exhaust system. When fully cured -- after 24 hours -- J-B Weld is as strong as metal and can be filed, sanded, or painted as necessary.

Things You'll Need

• Paper bowl
• putty knife
• acetone or lacquer thinner

Instructions

1. Clean the area around the crack with acetone or lacquer thinner. Ensure the area is clean and completely dry.

2. Mix the two components of J-B Weld in a paper bowl or other disposable container. Keep mixing until the color and consistency is even.

3. Work the mixture into the crack with the putty knife. Insert only enough to fill the crack so that you aren't pushing J-B Weld into the interior of the engine. Smooth the surface.

4. Dry the epoxy for at least 24 hours before starting the vehicle. In cold weather J-B weld may take longer to set, so allow more time before using the engine.

References

• J-B Weld
• J-B Weld: Uses
• J-B Weld: FAQ