Motorblokk

Motorblokk, or engine block, is the central structural component of an internal combustion engine. It provides the spaces for the cylinders and pistons, forms the lower enclosure of the combustion chambers, and serves as the main support for the crankshaft and other moving parts. The block typically carries the main bearing caps, mounts for accessories, and provisions for cooling and lubrication. The cylinder head, bolted on top with a head gasket, closes the combustion chambers and allows intake and exhaust flow.

Most engine blocks are cast from gray cast iron or aluminum alloys. Iron blocks are strong and wear resistant but heavier; aluminum blocks are lighter and dissipate heat faster, often using iron sleeves or cast-in bores to resist wear. Cylinder bores may be machined directly into the block or use replaceable liners. Engine blocks come in configurations such as inline, V, or horizontally opposed (boxer). The block contains water jackets for coolant circulation and oil galleries for lubrication, connected to the oil pan, oil pump, and filter.

Manufacturing and design considerations include the casting method (sand casting for iron blocks, die casting for some aluminum blocks), bore spacing, main bearing webbing, and reinforcing ribs. The deck surface must be flat to seal with the cylinder head. Blocks may feature dry or wet cylinder liners, integrated passages for cooling and lubrication, and mounting points for components such as the crankcase, timing gear, and cylinder head.

Maintenance and issues involve head gasket leaks, cracks or warpage in the deck, coolant or oil leaks, and wear of cylinder bores. Repairs may range from resurfacing and resealing to liner replacement or block replacement in severe cases.