Rick's Free Auto Repair Advice

What causes low oil pressure?

Most common causes of low oil pressure

The oil warning light in your dash comes on when oil pressure drops below 7-psi. In other words, when your engine has low oil pressure. Here are some common causes of low oil pressure.

A faulty oil pressure sensor can cause a false low oil pressure warning

An oil pressure sensor is built with a diaphragm oil pressure sensorand electrical contacts. Over time, the diaphragm can degrade and leak, causing the sensor to report a low oil pressure situation when the oil pressure is actually within specs.

To test for a faulty oil pressure sensor, either replace the sensor with a new unit or install a mechanical oil pressure gauge in place of the sensor to determine if the sensor it reporting accurately.

A low oil level can cause the oil light to come on

An engine circulates oil throughout the engine and it drains back to the oil pan to be recirculated again. When your engine is low on oil due to oil consumption or an oil leak, a low oil level starves the oil pump, causing a low oil pressure situation. If your oil light comes on, immediately check the oil level on the dipstick and add oil if it measures low.

The wrong oil viscosity can cause a low oil pressure light

All oil thins as it heats up. If you’ve filled your engine with the wrong oil viscosity, the thinner oil can cause the oil pump to struggle to maintain proper oil pressure. As a result, your engine may suffer from low oil pressure, especially during idle when the engine RPMs are low and the oil pump can’t keep up with the need for oil pressure.

A stuck oil pressure relief valve in the oil pump can cause low oil pressure

Every oil pump has a pressure relief valve to bleed off excess pressure at higher RPMS. If the pressure relief valve sticks, it will constantly bleed off pressure, causing a low oil pressure condition that appears most often at idle speeds.

Sludge in the oil pan can cause a low oil pressure condition

If you’ve neglected oil changes and developed a sludge enginesludge problem in the oil pan, the sludge buildup can restrict the oil pickup screen, causing oil starvation and low oil pressure. Cleaning the oil pickup can sometimes solve the problem.

Worn engine bearings can cause low oil pressure

Engines maintain oil pressure two ways; by a fully functioning oil pump and by maintaining proper bearing clearances. If bearings wear to the point where they can’t maintain oil pressure, even the best pump can’t keep proper oil pressure flowing.

A clogged or damaged oil filter can cause low oil pressure

Many oil filters contain a bypass valve to keep

oil filter caked with oil sludge

This is what sludge looks like on an oil filter

oil flowing around the filtration element when it gets clogged. If your oil filter has a faulty bypass valve, it will starve the oil pump and cause a low oil pressure situation.

Symptoms of low oil pressure

Oil light on
Clunking noise from the engine
Burned oil smell due to engine overheating
Poor engine performance
Engine overheating

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Posted on by Rick Muscoplat

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