Oil Pump
A mechanical pump that circulates engine oil under pressure to lubricate and cool moving engine parts.
The oil pump is the heart of an engine's lubrication system. Bolted inside the oil pan or low on the engine block, its primary job is to draw engine oil from the pan and pump it under pressure through oil passages to the engine's bearings, pistons, camshafts, and lifters, ensuring moving metal parts remain separated by a thin film of oil.
Most oil pumps are mechanical gear or rotor pumps driven directly by the crankshaft or camshaft. As the gears rotate, they mesh together to draw oil through a pickup tube (which has a screen to filter out large debris) and force it through the oil filter to the rest of the engine. A pressure relief valve prevents the pressure from rising too high at high engine speeds.
Proper oil pressure is critical; too little pressure allows metal-on-metal contact, leading to rapid engine wear or catastrophic engine failure (seized bearings). Too much pressure can blow seals and gaskets. Signs of a failing oil pump or low oil pressure include a flickering oil pressure warning light, clattering valve train noise (due to hydraulic lifters collapsing), and engine overheating.
If the oil warning light comes on, the engine should be shut off immediately. Diagnosing oil pressure issues involves connecting a mechanical pressure gauge to verify if the pump is failing or if the oil level is simply low.