Low oil pressure is a serious problem that you should never ignore. The issue can cause (or result from) internal engine problems that can leave you stranded and rack up a hefty repair bill. It’s a good idea to familiarize yourself with the symptoms and causes of low oil pressure so that you’ll be prepared if a problem occurs.
What Does Low Oil Pressure Mean?
Motor oil is essential for proper engine operation. The oil lubricates (provides a liquid barrier between) internal engine components, reduces friction, and helps keep the engine cool. There must be sufficient oil pressure so that the oil can circulate throughout the engine and reach the necessary internal components.
The oil pump, which is driven off of the engine’s camshaft, crankshaft, or distributor, pulls oil from the oil pan whenever the engine is running. From there, the pump forces the oil into the engine’s lubrication system. Oil pressure is created by the resistance the oil encounters while circulating through the engine.
Low oil pressure is just what it sounds like—a lack of oil pressure inside the engine. There are several reasons why an engine might be suffering from low oil pressure, as we’ll discuss below.
What Causes Low Oil Pressure?
There are several reasons why an engine might be suffering from low oil pressure. Some of the most common causes include:
Low Oil Level
A severely low oil level can result in a loss of oil pressure. It’s a good idea to check your oil once a week (more frequently if there are leaks) to ensure the level is sufficient.
Oil Quality Issues
Motor oil that’s diluted, aerated, or the wrong viscosity can result in low oil pressure.
Oil Pump Issues
If the oil pump doesn’t displace enough oil, the engine will suffer from low oil pressure. Low oil pressure can also result from an obstructed pump pickup screen.
Stuck Open Pressure Relief Valve
There is a pressure relief valve, which is typically located at the oil pump’s outlet. If the valve sticks open, the engine will experience low oil pressure.
Excessive Bearing Clearance
Over time, the crankshaft and camshaft bearings can begin to wear, resulting in excessive clearance between the bearings and their corresponding shaft. Because oil pressure is created by the resistance the oil encounters while circulating through the engine, excessive bearing clearance can lead to a loss of oil pressure.
Scored or damaged bearings can also result in low oil pressure, as can damaged camshaft lobes or crankshaft journals.
Oil Circulation Problems
Oil circulation problems, such as a cracked gallery or missing gallery plug, can result in low oil pressure. Also, infrequent oil changes can lead to sludge buildup inside of the engine, which can block passageways, restricting oil flow and causing pressure to drop.
Clogged Oil Filter
The engine oil filter contains a bypass valve that should open if the filter becomes clogged. When the valve opens, oil will be allowed to keep flowing to the engine, but oil pressure will still be reduced.
Low Oil Pressure Symptoms
A variety of issues can lead to low oil pressure. What’s more, sometimes other problems, such as a faulty oil pressure sensor, can create some of the same symptoms as low oil pressure. So, you (or your mechanic) should diagnose the vehicle thoroughly before performing any repairs.
With that in mind, here are the most common symptoms associated with low oil pressure:
Illuminated Warning Lights and/or a Low Oil Pressure Gauge Reading
Depending on the vehicle’s design, an oil pressure sensor or oil pressure switch (or both) may be used to monitor engine oil pressure. If an oil pressure switch is used, the switch will close in response to low oil pressure, causing the oil pressure warning light to illuminate on the dashboard.
When an oil pressure sensor is used, the oil pressure gauge reading on the dash will be low when oil pressure is low (an oil pressure warning light may also turn on). In some instances, the check engine light will turn on in response to low oil pressure, as well.
Internal Engine Noise
Low oil pressure can quickly lead to abnormal noises coming from the engine. At first, you may hear rattling, ticking, or tapping sounds from the timing components (if the engine has a timing chain) or the valve train.
If you continue to ignore the issue, the sound will eventually turn into a knocking noise from the crankshaft bearings in the engine’s bottom end. Once those bearings start making noise, it’s not long until the engine seizes.
Vehicle Runs Rough
Most late-model vehicles are equipped with variable valve timing (VVT). The technology relies on engine oil pressure to activate a camshaft-mounted actuator, which changes the angle of the camshaft to alter valve timing. Low oil pressure can prevent the VVT system from operating properly, resulting in an engine that runs rough and lacks acceleration.
Low Oil Pressure FAQ
Low oil pressure is bad news because it can quickly lead to catastrophic engine failure. If you note any of the symptoms associated with low oil pressure, you should pull over and shut the engine off immediately. Then, have the vehicle towed to your location of choice for diagnosis and repair.
Unfortunately, there isn’t a one-size-fits-all solution for low oil pressure. The root cause of the issue could be anything from a low oil level to excessive bearing clearance inside the engine. If your vehicle is suffering from low oil pressure, the engine will need to be diagnosed and properly repaired.
Any information provided on this Website is for informational purposes only and is not intended to replace consultation with a professional mechanic.