How to Fix a Cracked Engine Block

What You'll Need
Metal stitch kit
Wire brush
Tag rag
Damp cloth
Torque wrench

A cracked engine block might seem like an absolute disaster for your car. As the engine block is one of the most vital components of your vehicle, a damaged block can create numerous problems and consequences. If you see signs that your engine block is cracked, you have some options, so don’t worry that all is lost. There are methods by which you can repair the block using welding, chemical sealants, or epoxy and stitching kits.

Step 1 - Prepare the Block

The engine will very likely have to be removed, so be prepared to do this. It is not an easy job and it takes quite a serious amount of dismantling of parts and components to get the block out. You might also require a hoist. If the engine block is already removed you can proceed to fix it.

Step 2 - Assess the Crack

How deep or long the crack is in your engine will determine the best way to fix it. It will also determine whether it can be fixed. Cast iron is not easy to weld and it takes a very skilled person to mend a cast iron engine block with welding equipment. If the crack is less than 8 inches long and less than 1/8 of an inch wide, it is very probable that you can fix it with a metal stitching kit and epoxy.

Step 3 - Clean the Wound

The crack needs to be completely clean before you proceed any further. Use the wire brush to clean the crack and ensure there is no residue grit, grime, or dirt in and around the crack. If the crack is too wide to use the brush then just wipe it clean with a damp cloth and use a tag-rag. Even the most minute pieces of grit or dust can cause issues with the cylinders, so do not let any get inside the crack.

Step 4 - Stitch the Wound

Take a "stitch" from the kit and insert it into the crack with the hammer. Depending on the type of kit you buy, your stitch may or may not have "shoulders." The shoulders help you to hammer the stitch deeper into the crack for better adhesion and a cleaner finish. Other stitches might be equipped with break-off grooves that can be taken off at a predefined place, once inside the crack with the torque wrench.

Step 5 - Use Epoxy

Use an epoxy compound suitable for engine block repair. With the stitches in place, apply the epoxy into the crack as far as you can put it and then fill the crack completely. Cover over the surface and smooth the epoxy for a neater join. Leave it to dry thoroughly for however long the recommended time states on the instructions. Your engine block should now look and be as good as new. As a final word of caution, always be sure that what you are doing is the correct procedure and do not attempt this if you are uncertain.