7 Causes of Low Oil Pressure on Diesel Engine

There are many important parameters in a vehicle and your oil pressure is just one of them. If you notice that the light of your oil pressure comes on, that might be a sign that there is a with the oil pressure. The light comes on because the pressure gauge has reported that the oil pressure is abnormally low. Low oil pressure usually signifies a huge problem. However, there are instances where the problems could be resolved quite easily. This post is going to explain some of the most common causes of low oil pressure in a diesel engine.

7 causes low oil pressure on diesel engine

The engine oil helps to lubricate all moving parts of the engine and it also protects them.  The oil builds up pressure when it is flowing through the engine and the pressure ensures the oil comes in contact with every necessary part and components of the engine. However, if there is low oil pressure, the various components in the engine will come in contact and this might cause friction. The worst thing that low oil pressure could cause in a diesel engine is to break it down.

To avoid engine damage, you need to ensure you have the right amount of oil pressure in your engine. The total amount of oil pressure needed in a vehicle is different due to their models and brands. If the oil pressure in a vehicle is lower than 20 PSI, or below its normal range, then it needs urgent attention. A low oil pressure will trigger the oil pressure light and you will notice it. If you ignore and refuse to treat the problem, it will lead to engine damage which will cost you a fortune.

The ways you can prevent low engine oil is by avoiding anything that could lead to it. Below are some of the causes of low engine oil in a diesel engine.

Insufficient motor oil

This is the number one cause of low engine oil pressure. The first thing you need to do once you notice the light pressure is on is to check the crankcase. It does not matter if you recently changed the oil or not. There are various things that could consume the oil. It could be a leaking seal or worn piston rings. An old engine will consume oil faster that a new one so you need to keep an eye on your engine. Ensure you solve whatever that is making the engine consume oil faster than normal. Also check the oil level of your engine and if you notice that it is below the oil pump, just top it. You can check the instructions of your vehicle to know the correct level of oil to add to the engine.

Engine oil contamination

Another cause of low oil pressure is if there is any contaminant in the oil. It could be coolant, fuel, or fluids that have been building up in the oil. This could lead to high level of oil in the crankcase. This will eventually lead to leaking of fluid in other parts of the engine. Contaminants such as coolant, fuel, water, or diesel in the oil will eventually lead to low engine oil pressure. If this is the case, that source of the contaminants needs to be found. It could be that the contaminant is leaking into the oil. If that is the case, it needs to be fixed as soon as possible. After fixing, the oil should be changed and refilled to its exact position.

Clogged oil filter

Once the oil leaves the pump, it travels through the oil filter. The oil filter is the component that prevents debris from passing the engine. It naturally slows down oil and removes any dirt that might be inside. However, as the time goes on, it builds up and might begin to get blocked to the extent that oil will be unable to pass through it. Once this happens, the pressure relief valve will automatically open so that oil will bypass the filter and keep flowing. This will reduce the pressure of the oil.

If the oil filter is clogged, it simply means that the oil has different types of contamination. You will either need to replace the filter of get it cleaned. Once that is done, you drain the oil and refill it.

Low or high viscosity

Another cause of low oil pressure is if the oil viscosity is too low or very high. A high viscosity will cause resistance when the oil is pumping and this might cause lack of lubrication which will in turn lead to a low pressure. If the viscosity is also low, it will lead to less resistance of oil flow and also cause low oil pressure. The manual of every car has the recommended grade of viscosity which is usually according to the engines design. It is important that the oil viscosity remains at its recommended grade.

Engine wear

The probability of an older engine having a low blood pressure is higher than a new engine. You might have to change the oil in your engine frequently once it starts getting old. The reason for this is because the metals are wearing due to the age of the engine. Some of the parts of the engine will begin to need more lubricant due to their condition. This is because there would be no more restriction of oil as there used to be. So, if your engine is quite old, you might need to keep changing your oil frequently than usual.

Faulty oil pressure gauge

This could also trigger the light of your oil pressure. If you check the oil and its at the normal level, you might get confused. The problem might be that the oil pressure gauge is defective. You should get it tested and replace the sensor if necessary.  If the problem persists after replacement, then you should check the oil pump.

Faulty oil pump

A worn oil pump could lead to the oil pressure light coming on. The pump will be unable to produce the necessary pressure due to leaks. So, you need to make sure it is checked out immediately. If the oil pump is faulty, it needs urgent replacement.


In summary, there are so many things that can cause low oil pressure in the diesel engine. If you notice the oil pressure light is coming on, you need to shut off the engine immediately. If you do not do this, you risk damaging your engine. However, it might be a simple problem like a faulty pump or pressure gauge. Whatever the problem might be, you need to get it look out.

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