How To Repair a Cracked Engine Block

 In Belzona Educates, How To Series

Introduction to Cracked Engine Block Repair

A cracked engine block in a vehicle is not uncommon. What might seem like a disastrous situation, does not necessarily mean the end of the engine’s lifespan. The cracks can lead to a series of problems, for that reason they need to be eliminated.  Therefore, there are various methods of repairing cracked engine blocks: from welding and brazing, to cold metal stitching. Belzona offers a solution that does not require hot work or specialist tools.


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Belzona How-To

For the repair of this cracked engine block, we used Belzona 1111 (Super Metal),  Belzona 9111 (Cleaner/Degreaser), Belzona 9341 (Reinforcement Tape), and a few tools from our machine shop. The engine had a few hairline spider cracks. After the surface was thoroughly cleaned, and the cracks were terminated by drilling and tapping small holes at their ends. Studs were then threaded into the holes and cut flush with the casing. The cracks were veed out with a grinder, and the repair area was thoroughly roughened. Belzona 1111 was mixed and applied directly onto the cleaned surface. A small piece of reinforcement tape wetted out with the mixed material was applied over the crack and encapsulated into the Belzona material already applied. Remaining mixed material was applied onto the entire area to create a buildup of approximately 1/8″ (3 mm). The entire application took less than an hour.

Drawing: Cracked Engine Block Repair with Belzona 1111

Cracked engine repair

Video: Cracked Engine Block Repair

Supplies and Tools Used for this Cracked Engine Block Repair

Step-By-Step Instructions of Cracked Engine Block Repair


Clean Repair Area

Cracked engine block repair: prepare surface

Thoroughly clean the repair area. Remove all dirt, grease and other contaminants.

Degrease Repair Area

Cracked engine block repair: clean/degrease the repair area

Use Belzona 9111 (Cleaner/Degreaser) to degrease the repair area.

Terminate Cracks

Cracked engine block repair: terminate cracks

To terminate the cracks, drill 3/16″ (48 mm) holes at their ends to prevent further propagation.

Tap Holes

Cracked engine block repair: tap holes

Tap the holes

Remove Residue

Cracked engine block repair: remove all residue

Using Belzona 9111 (Cleaner/Degreaser) remove all residue to keep the repair area free of contaminants.

Insert Studs

Cracked engine block repair: insert studs

Insert studs into each hole.

Cut Studs

Cracked engine block repair: cut off the studs

Cut the studs flush with the casing.

Vee Out Cracks

Cracked engine block repair: vee out the cracks

Vee out the cracks using a grinder.

Roughen Surface

Cracked engine block repair: clean the repair area

Roughen the surface, and degrease the application area with Belzona 9111.

Tape Repair Area

Cracked engine block repair: tape the repair area

Mask off the repair area.


Mix Belzona 1111

Cracked engine block repair: mix Belzona 1111

Measure Belzona 1111: 3 parts Base to 1 part Solidifer by volume, and mix thoroughly.

Prepare Reinforcement

Cracked engine block repair: wet out the repair area

Wet out a suitable length of Belzona 9341 (Reinforcement Tape) with the mixed product.

Apply Belzona 1111

Cracked engine block repair: apply Belzona 1111

Apply a thin film of mixed product onto the prepared area, pushing the product well into the roughened profile.

Encapsullate Belzona 9341

Cracked engine block repair: encapsulate reinforcement tape

Bed the wetted layers of Belzona 9341 down over the crack into the product already applied.

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Showing 3 comments
  • jim borne

    where can I find this product and what is the cost?

    • Yulia Burova
      Yulia Burova

      Dear Mr. Borne,

      Thank you for your interest in Belzona products. Please fill out a contact form on this page: and one of the Belzona representatives in your area will assist you.

      Best regards,
      Belzona Team

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  • […] our previous block post “How to Repair a Cracked Engine Block”, we already demonstrated an application with cold-applied epoxy-based Belzona 1111. In this blog […]

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