motorblock

The motorblock, or engine block, is the main structural component of an internal combustion engine. It forms the rigid frame that supports the crankshaft, connects the cylinders, and provides mounting points for other components such as the cylinder heads, intake and exhaust manifolds, and auxiliaries. The block also encloses the combustion chambers and includes passageways for coolant and lubricating oil.

In typical designs, the block contains cylindrical bores for the pistons and often incorporates cylinder liners or sleeves. It is built from cast iron or aluminum alloy, with cast iron offering strength and wear resistance, while aluminum reduces weight and improves heat management but requires more complex oil and cooling designs. Most modern engines use a closed-deck or semi-closed-deck design to improve rigidity, and the cooling system circulates coolant through water jackets surrounding the cylinders.

Manufacturing methods include sand casting for iron blocks and high-pressure die casting or machining for aluminum blocks. Final machining creates precise bore diameters, seal surfaces, and mounting faces. The engine block also provides oil passages and oil galleries connected to the oil pan and pump, and cooling passages linked to the radiator. The cylinder head seals to the block via a head gasket and bolts, forming the combustion chamber and allowing proper sealing under high temperatures and pressures.

Common failure modes include warping, cracks from overheating, coolant leaks, and oil leaks at gaskets. Maintenance focuses on proper torques for head bolts, coolant quality, and monitoring for leaks and unusual noises.