How do I Fix my Cracked Block?

A cracked block can be a difficult problem to diagnose.  Many times, these cracks manifest themselves in small coolant leaks and are often in the most obscure and hard to see areas of your engine block.  Most cracked blocks happen due to constant stress concentrated in a certain area of your block over a long period of time finally causing a fracture.  Some blocks crack catastrophically due to high cylinder pressures, excessive engine RPM or extreme overheating.  For the most part, engine blocks crack much more subtly due to these small cyclical stress over a longer period of time.

The corners and pockets in the casting of your engine block are the perfect place for heat stress to build up and for vibrations to cause even more stress to gather.  The cast iron your engine block is made of is a very strong and hard metal, but these characteristics also make it relatively brittle.  In some cases, these stress combined with a brittle material can cause cracking especially if it is near an area with thinning metal due to corrosion or erosion in the cooling chambers.

Cracks like these often show up as mysterious cooling system leaks that seem almost impossible to identify.  The most common areas of the block to crack are at the bottom of the cooling passages where the block juts out to accommodate the oil pan and gasket.  On most engines, these areas are covered by the intake or exhaust manifold, engine accessories, or other equipment in the engine bay like air filters, emissions control components or electronics.

The other thing that makes a cracked block difficult to identify is the scaling on the outside of your engine block will make it very difficult to see the crack.  In many cases, the cracks also will close up as your engine cools and the metal contracts making it nearly impossible to find during the inspection of a cold engine.

If you suspect you have a crack in your block, the easiest way to find it is using UV dye.  Simply add UV dye to the coolant in your cooling system and drive like normal for a few days.  Then park your vehicle in a dark area, like a closed garage, and use an ultraviolet or black light to find the leak location.  The UV dye should stick along the edge of the crack making it more obvious.  You can also try using a grinding tool to remove the scale from the engine block in the area you suspect a crack to be in order to help make it visible.

When you’ve found the crack in your engine block the next question is how to repair it.  There are various options but many of them have unproven track records of working well.  Methods like cold metal stitching or drilling and tapping the crack don’t always give consistent results.  Cast iron can indeed be welded, but needs to be done in a very controlled environment and can rarely be done while the motor is still assembled or in the vehicle.

The best option you have for fixing your cracked block is to use BlueDevil Radiator and Block Sealer.  BlueDevil Radiator and Block Sealer is a chemical sealing agent that will form a barrier on the inside of the crack in your engine block sealing your cooling inside allowing you to continue using your vehicle leak free!  BlueDevil Radiator and Block Sealer is not a particulate sealer so it will not harm or damage your cooling system.

For more information about BlueDevil Radiator and Block Sealer, click on the banner below!

You can find BlueDevil Radiator and Block Sealer at any of our partnering local auto parts stores like:

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cracked_block.jpg – By uatp2 – Licensed by Thinkstock Photos – Original Link