Engine Block
The large, solid metal structure that houses the engine cylinders, pistons, crankshaft, and water jackets for cooling.
The engine block, also known as the cylinder block, is the structural foundation of an internal combustion engine. Typically cast from aluminum alloy or cast iron, it contains the cylinders where the combustion process takes place. It also houses the pistons, connecting rods, and the crankshaft, providing the rigid framework necessary to contain the extreme pressures and forces generated by the running engine.
Intricate pathways called water jackets are cast into the engine block, allowing engine coolant to flow around the cylinders to absorb heat and prevent overheating. Similarly, oil galleries are drilled throughout the block to deliver pressurized lubricating oil to the crankshaft bearings, pistons, and valvetrain components. The cylinder heads bolt to the top of the block, while the oil pan bolts to the bottom.
Due to its solid construction, the engine block rarely fails under normal conditions. However, severe overheating or freezing coolant (lacking proper antifreeze mixture) can cause the block to warp or crack. A cracked block can lead to internal oil and coolant mixing, external leaks, or loss of cylinder compression, which usually requires replacing the entire engine assembly.