Causes of low oil pressure in engines
Oil pressure is one of the most important parameters of an engine. If your vehicle’s oil pressure light comes on or the pressure gauge shows a lower than normal reading, it may be that there is a serious problem. Unfortunately, you won’t know if the problem is serious or not. Therefore, it is best to simply shut off the engine.
Causes of low oil pressure
Oil pressure in an engine can drop for a variety of reasons. If the pressure gauge indicates a drop in oil pressure, you should be aware that this may be real or simply an inaccurate result. In either case, it helps to understand some of the most common causes.
1) Not enough oil in the engine
Even if the right amount of lubricant is added during an oil change, excess oil can be consumed due to evaporation, burnt piston rings due to wear, leaks from seals or oil plugs, etc. As engines age, oil consumption increases, so checking and topping up the oil level is a simple solution.
Older engines use more oil. If your engine consumes a quart of oil every 1,000 to 2,000 miles, it needs an overhaul. If the oil change interval is too long, the oil level can drop considerably, even if the engine is not that old. So, maintain the correct oil change interval and check the oil level regularly.
2) Viscosity too high or too low
If the viscosity of the oil is too low or too high, this can be detected as a pressure loss in the engine’s oil supply. Low viscosity provides less resistance to flow in the system and is interpreted as low pressure by the pressure gauge or sensor.
Too high a viscosity can provide more resistance to the oil being pumped, leading to a lack of lubrication in the system and a resulting drop in pressure.
In an engine, oil viscosity is affected by the initial viscosity of the selected lubricant, the operating temperature, deterioration of viscosity index improvers, and the presence of contaminants such as glycol and soot. Your engine or vehicle manual should provide recommended viscosity grades depending on the equipment design and the ambient temperatures in which the vehicle will operate. Choosing a higher viscosity can cause problems starting the engine, especially in cold weather.
3) Apparent Low Pressure
For diesel engines, pressure gauges typically display real-time pressure in pounds per square inch or bar. Some lubricant manufacturers produce lubricants with lower viscosities, even within the SAE grade range.
Lower viscosity allows for better flow through the lubrication system, but can result in lower pressure in the pressure gauge. If the pressure is within the normal range, there is no need to worry. Some lubricants may develop higher pressures than others.
4) Engine wear
If the oil level on the dipstick is between add and full, worn engine bearings may be the cause of the pressure drop, especially if the engine has had a lot of mileage. Excessive wear reduces the original flow restriction, resulting in a drop in pressure. In this case, the engine may need to be rebuilt or replaced.
5) Faulty oil pressure gauge
If the oil pressure warning light comes on but the oil level is correct, there is no abnormal noise or high temperature, and the engine is running normally, the sensor unit may be faulty.
You should have the oil pressure checked with the gauge. If the pressure is normal, you only need to replace the oil pressure sensor. However, if the warning light or low value remains on after replacing the sensor, the oil pump may be faulty.
6) Worn pump
If the oil level on the dipstick is between top up and full, but the engine is noisy, the oil pump may be worn out. A worn pump cannot generate the required pressure due to internal leakage. Shut off the engine until the problem is fixed. The pump must be replaced.
7) Clogged Filter
In a lubrication system, the pressure gauge is installed after the filter. A clogged filter is often caused by too much oil.
It can also be caused by water or soot contamination. Water is usually caused by a leak in the cooling system, while excessive soot can be caused by poor combustion. If the bypass valve is not working properly, a faulty filter may be the cause.
Above is a flow chart detailing the inspection and action to be taken when engine oil pressure drops.
