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4 Causes of Cracked Engine Blocks
JANUARY 9, 2013 By POWERTRAIN PRO

The Only Real Reason For Cracked Engine Blocks

While there are many underlying causes of cracked engine blocks, they almost all involve excess heat. Engine coolant is what’s supposed to keep the overall engine within operating temperature, but extreme overheating changes things. In these instances, the coolant isn’t enough to keep all of the block cool (because it can only cool the immediate area through which it runs). The overheated portions expand while the cooler areas don’t. The result is stress on the block and then an engine-killing crack. So, what causes overheating?

Low coolant is the primary cause of overheating. If your customer runs their engine with the low coolant light on, they should expect to suffer some very serious problems. Whether the situation was caused by failure to maintain their coolant properly or their radiator failed, the situation can be very serious if not caught in time, especially in used car engines for sale.

Water pump failure is another thing that can cause a cracked block. Even if the coolant level is fine, without a functional water pump, the coolant can’t flow through the system and cool as it is designed to do. This can lead to severe overheating and a cracked block.
Casting failure is the third cause of engine block cracks. While rare, it does happen. During the injection molding process, a shift in the mold’s sand can cause the block’s metal to be thinner than necessary in certain areas. Over time and with the application of heat (expansion and contraction), these thin areas can crack.

Overheating due to overpowering is another cause of cracked engine blocks. Adding a supercharger or turbocharger to an engine not designed for one can create a situation in which the engine has more power (and generates more heat) than it can handle. This creates extra flexing and expansion in the block (because the coolant can’t handle the amount of heat generated by the added power), resulting in a cracked block.

In most instances, replacing an engine with a cracked engine block is the best solution, particularly if your customer is interested in a salvage engine or a rebuilt engine (both of which are more economical than crate or remanufactured engines).