An engine oil pressure gauge is typically located in the driver's dashboard, to give the pressure readings at which the engine oil is delivered to the engine moving parts. In this article, I will discuss What is Oil Pressure Gauge and the different types of gauges and their working principle.

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What is Oil Pressure Gauge?

An oil pressure gauge is mounted on the instrument panel of all cars equipped with a pressure lubrication system to tell the driver what the oil pressure is in the engine. This gauge is important because there is a constant pressure always running whenever the engine starts. 

In the lubrication system, the lubricating pump is used to pressurize and deliver the oil to the moving bearings at high pressure. This high pressure gave the engine a smooth running condition to operate at high speeds. Without sufficient oil pressure, the oil film between the moving parts can be disturbed and wear and tear can lead to the bearings. 

The engine oil pressure gauge typically has a dial or digital display that shows the oil pressure. This pressure basically shows in pounds per square inch (psi) or in kilopascals (kPa). If the oil pressure gauge shows an unusually low reading or drops suddenly, it may indicate a potential problem with the engine's lubrication system, such as low oil levels, a failing oil pump, or a clogged oil filter. In that case, it is advisable to replace or check the oil pump for a better engine lifespan.

Oil Pressure Gauges Types- 

Oil pressure gauges types depend upon the working principle and the design of the engine. In the earlier days, there were mechanical-type engine oil pressure gauges used. But after the automotive industry introduced the engine ECU the gauges are coming with electric features. 

The oil pressure gauges are the following types-

1. Pressure Expansion Type Oil Pressure Gauge.
2. Electric Type Oil Pressure Gauge.

Electric type gauge has 2 different versions -

1. Balancing Coil Type.
2. Bimetal Thermostat Type.

Pressure Expansion Type Oil Pressure Gauge

Pressure expansion type oil pressure gauge was used in most machinery because of the simple design and precise working temper. It operates on the principle of pressure expansion, which involves the use of a flexible diaphragm or a Bourdon tube to detect and convert oil pressure into a mechanical motion.

It consists of a hollow bourdon tube, that is fastened at one end and free at the other. The oil pressure is applied to the curved tube through an oil line from the engine which causes the tube to straighten out. This movement is transmitted to a needle by linkage and gears from the end of the tube. The needle moves across the face of the dial indicating the oil pressure.

Electric Type Oil Pressure Gauge

Electric type oil pressure gauge comes after the problems and troubleshooting of the mechanical pressure type oil pressure gauge. Electric-type oil pressure gauge is popular because of the precise timing and the precise indicating pressure level detecting power.

One advantage of electric gauges is that they eliminate the need for mechanical linkages and potential points of failure in the gauge mechanism. However, they do rely on a functioning electrical system to provide accurate readings. Therefore, it's essential to ensure the gauge's wiring and sensor connections are secure and functioning correctly.

Electric-type oil pressure gauge is of two types-

1. Balancing Coil Type Electric Oil Pressure Gauge

This type of gauge is generally shown in modern vehicles. The accuracy and the precise readings make the engine lifespan better. 

It consists of two separate units- the engine unit and the indicating unit. The engine unit consists of a moving contact that moves over a resistance according to the varying oil pressure against a diaphragm. As the pressure increases, the diaphragm moves inward by which the contact moves along the resistance so that more resistance is placed in the circuit between the engine and indicating unit.

This reduces the amount of current flowing in the circuit. The indicating unit consists of two coils that balance the movement of the pointer on a scale, in a manner similar to an electrically operated fuel gauge. 

2. Bimetal-Thermostat Type Oil Pressure Gauge

The Bimetal-Thermostat Type Oil Pressure Gauge utilizes the temperature sensitivity of the bimetallic strip to translate the engine oil temperature into a mechanical movement, which is then converted into an oil pressure reading.

The bimetal thermostat-type oil pressure indicator is similar to the bimetal thermostat fuel gauge. It consists of an engine unit and a dash unit. The oil pressure on a diaphragm distorts the engine unit thermostat blade and this distortion produces a similar distortion in the dash unit thermostat blade, causing the oil pressure to indicate on the dial. 

Ending Up With

A driver should pay attention to the engine oil pressure gauge to ensure the engine's optimal performance. 

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