Engine Oil Flow Diagram: What You Need to Know!

Once you’ve poured the engine oil into the engine, it usually flows through the engine causing it to lubricate three critical parts which include the main bearings, pistons and valve train.

You can use the oil flow diagram to have a more in-depth look at the passing of the oil throughout the engine.

It’s safe to say that the oil flow diagram of an engine is considered to have nine components. While they may vary depending on the type of engine you’re working with, the functioning and positioning is known to remain the same so you don’t have to worry about getting confused.

In this article, we are going to explain the nine components of the engine flow diagram so that you can have a better understanding of how it actually works.

Engine Oil Flow Diagram: Nine Components

Engine Oil Flow Diagram
Image source: https://www.kirmanual.com/engine_oil_flow_diagram-197.html

1. Oil Filter Port

Base on the diagram you can see that the oil filler port is located at the top of the engine and this is where the oil is usually added. Once you’ve pour the oil inside it passes down to the bottom of the engine.

2. Oil Pan

You can find the oil pan at the bottom of the engine where the oil is collected and transformed into an oil sump.

3. Sump Strainer

The sump strainer is known to be a floating strainer plate that can be found on the oil surface of the pump. It work as an inlet port for the oil pump so that it can suck up the oil from the sump. The filters plays a role in removing the debris while also preventing the entry of larger particles into the oil pump.

4. Oil Pump

The oil pump main duty is to pump the clogged oil which allows easy flow as it pressure the liquid to reach small spaces and travel until the end of the cycle.

5. Oil Filter

The oil filter main task is for separating the microscopic particles from the pumped oil. You should take the time out to replace the oil filter when you are changing the engine oil.

6. Oil Galleries

You will find that the filtered oil goes to the main gallery from the oil. The primary is the one to absorb the oils, then feed it to other parts of the engine through smaller tubes.

7. Feed to Crankshaft, Connecting Rod, Camshaft, and Big-End Main Bearings

At this point, you will notice that a tube from the main gallery takes out the oil which allows it to feed the crankshaft and connecting rods. Another tube will then passes oil to the camshaft assemblies, where the main oil gallery lubricates the big-end main bearings.

8. Feed to Cams, Valve Lifters, Rocker Arms, Push Rod, Tappet, and Cylinder

Another tube from the main gallery will transfer oil up to the assemblies in the cylinder head. These assemblies include cams, valve filters, rocker’s arms, push rods, tappets, and cylinders.

The cylinders is known to have small holes which oil flows through and cool down the cylinder and engine block. Apart from that small holes can be found around the piston rings and oils that splashes from the crankshaft helps to lubricate the piston.

9. Oil Pressure Gauge

A tube also goes from the main galleries into the pressure gauge, where the oil passes through and presses against a diaphragm. The oil pressure gauge plays a very important role since it monitor your engine’s health and working condition.


As you can see, there are nine components of the oil flow diagram. These components include oil filters which helps to separate microscopic foreign particles, and oil pumps which plays a role in building the necessary pressure, which passes to the main galleries and the other engine parts.