Oil pumps are an integral part of a vehicle's mechanical system. While it's rare that they need service or cause problems, a bad oil pump occasionally can negatively impact a vehicle's performance and cause a variety of mechanical problems.
Low Oil Pressure
An oil pump is responsible for pressurising engine oil and pumping it through a vehicle's engine. A bad oil pump loses its ability to adequately pressurise and pump engine oil, resulting in low engine oil pressure.
Adequate engine oil flow helps keep an engine's operating temperature down by reducing engine friction. A bad oil pump can lead to an increase in engine operating temperature by restricting normal engine oil flow, reducing engine oil lubrication and increasing engine friction, which leads to an increase in engine operating temperature.
Noisy Hydraulic Lifters
An engine's hydraulic lifters, which are an important valve-train component, require adequate oil lubrication to function properly and quietly. Reduced oil flow and pressure caused by a bad oil pump can result in decreased oil flow to an engine's hydraulic lifters, which leads to hydraulic lifter noise and wear.
An engine's valve-train system--including pushrods, valve guides, and seals--requires adequate oil flow and lubrication to function properly and quietly. A bad oil pump can cause an engine's valve train to become noisy by reducing oil flow to the entire valve-train system.
Oil Pump Noise
In rare cases, a bad oil pump will make noise, normally a loud whining or whirring sound that can be heard when a vehicle is idling. As an oil pump's internal gear mechanism deteriorates and wears, the oil pump will make noise as it begins to fail.