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How to Tell if Your Oil Pump Is Failing

Mia Bevacqua
October 22, 2018

The oil pump delivers a fixed quantity of pressurized oil to the engine, in order to keep it running smoothly. Without the right amount of oil pressure, critical engine parts can begin to rub together, causing extensive — and expensive — damage.

» LEARN MORE: Get an estimate for your oil pump replacement

Signs of a failing oil pump  

These are some of the common symptoms associated with a failing oil pump:

  • Low oil pressure: A worn or failing pump will cause a loss of oil pressure. When this happens, internal engine components, such as bearings, camshafts and crankshafts, are starved of pressurized oil. When this happens, the engine will quickly get damaged.
  • Warning lights: The engine’s computer monitors oil pressure. If the module senses that it’s too low, it will turn on the oil pressure warning light. On most cars, it will turn on the check engine light as well.
  • Vehicle won’t start: Loss of oil pressure can prevent a vehicle from starting. On some cars, fuel delivery to the engine is cut when the oil pressure drops below a certain point. 
  • Engine noise: When certain engine parts don’t get enough oil, the engine may start to make tapping, knocking or rattling noises.
Get it diagnosed by a professional
 

How the oil pump works

The oil pump doesn’t actually create pressure on its own. Instead, the pressure is created as oil move through tight passages inside the engine.

An oil pressure relief valve located at the outlet of the pump opens to keep the pressure from getting too high. The desired value is typically between 10 and 80 PSI, depending on your engine’s design, speed and temperature.

Most vehicles use one of two basic pump designs:  

  • Gear: This type of pump has two gears on the inside. Oil is pulled into the pump through the inlet, then flows around the outside diameter of each gear and exits through the outlet.
  • Rotor: This type of pump contains an inner rotor and an outer rotor. As the lobes of the two rotors come in and out of mesh, oil is pulled in through the pump inlet and forced out through the outlet.

In the past, the oil pump was mounted to the bottom of the engine, inside the oil pan. It was usually driven off a shaft connected to the camshaft or distributor. But on most modern vehicles, the pump is found in the front cover and is turned by the crankshaft.

Regardless of which design is used, oil is pulled into the pump from the oil pan. The fluid first passes through a screen to remove debris, then travels through a tube to the pump.

How to fix a bad oil pump

If you suspect a bad oil pump or loss of oil pressure, stop driving your car immediately. Have it towed to a repair facility and assessed by a professional mechanic. 

It may be possible to get away with just replacing the pump. But, in many cases, when the pump fails, it starves the engine of oil pressure and causes internal damage. In this case, the entire engine will need to either be rebuilt or replaced.

Mia Bevacqua

About the Author

Mia Bevacqua is an automotive expert with ASE Master, L1, L2 and L3 Advanced Level Specialist certification. With 13-plus years of experience in the field, she applies her skills toward writing, consulting and automotive software engineering.

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