How to fix a Broken Engine Block Your engine block is the sealed heart of your automobile,holding together all of the truly important components like your cylinders and cylinder heads. Often made of cast iron or aluminum,the parts in your engine block can develop cracks and damage over time Autel MaxiTPMS TS101. While it is possible to fix a broken engine block,it's important that you carefully evaluate the damage and figure out whether it would be more time and cost effective to simply have your engine block completely replaced. Things You'll Need Engine block epoxy Engine block sealant Gloves Sandpaper Instructions 1. Let your engine cool if it was recently on. Examine the damage to the engine block. If the damage is internal,you'll need to use an internal sealant. If the damage is on the surface,such as a crack or gap in the casing that you can see you'll need to use a filler epoxy. 2. Use epoxy to seal the external cracks. While wearing gloves,fill the crack or gap with the epoxy according to the instructions on the box. Most epoxies,like the popular JB Weld,come in two tubes -- a base and a hardener. Fill the crack with the base and then mix it with the hardener and let it cure for the amount of time listed on the package. Once the epoxy has cured and the repair made,sand down any remainder that's sticking out of the gap. 3. Use an internal engine block sealant. With the motor cool,lift the hood and open the radiator cap. Pour the recommended amount of engine block sealant into the radiator based on your engine size and then close the radiator cap again Autolink AL539B Scanner. Turn on the heater and fan to the maximum and then switch on the engine. Run it at 1,000 rpm for 60 minutes,then turn the engine off and allow it to cool. Top off the radiator with water and antifreeze.