Crankshaft Bearings
Precision-engineered journal inserts that support the crankshaft inside the engine block, allowing smooth rotation.
Crankshaft bearings (often divided into main bearings and connecting rod bearings) are two-piece metal shells that support the spinning crankshaft and connecting rods inside the engine. They are held in place by bearing caps bolted to the engine block and rods, providing a low-friction mating surface for the crankshaft journals.
These bearings do not run metal-on-metal; instead, they rely on a thin film of pressurized engine oil supplied through passages in the crankshaft. This oil film supports the load, keeping the moving parts separated. The bearings are made of soft, multi-layered metal alloys (like copper, aluminum, and lead) that can absorb microscopic particles, protecting the harder crankshaft journals from wear.
If engine oil pressure drops or the oil becomes contaminated, this protective film disappears, causing metal-on-metal contact. This quickly destroys the bearings and journals, leading to a deep knock noise (rod knock) and eventual engine seizure. Replacing bearings requires an engine rebuild, highlighting the importance of regular oil changes and maintaining proper oil pressure.