An air filter is an important component is a bike’s engine that ensures clean air for proper combustion. It traps dirt, dust, and other particles that could damage the engine.
You should not find oil in the air filter box.
If there’s oil in your motorcycle air filter box, a leak in the oil system, worn piston rings, clogged breather tubes, worn-out seals, or a faulty oil cooler could be the cause.
Although oil in the air filter doesn’t translate to immediate engine damage, it can cause a decrease in performance and engine failure if ignored.
This article discusses the possible causes of oil in a motorcycle oil filter box and how to solve them. Keep reading!
How a Motorcycle Oil Filter Works
An air filter box is a component that removes impurities from the engine oil. It is located near the bike’s engine and connected to the oil pump.
The filter box has a filter element that traps dirt and other particles as oil flows through it. It comprises layers of filtration media with different pore sizes that enable it to capture all types of particles.
When the bike’s engine runs, oil is pumped from the sump through the filter. Here, contaminants are trapped in the filter element, while clean oil offers the engine adequate lubrication and protection.
The clean air moves to the engine’s combustion chamber, mix with fuel, and ignites to power the bike’s engine.
In cases where the oil filter is improperly installed or the O-ring (gasket) is missing or damaged, oil can leak out and end up in the filter box. This oil can be a problem as it can transport impurities back into the engine, contradicting the purpose of the oil filter.
What Does it Mean When there is Oil in the Air Filter?
If you find oil in your bike’s air filter, there is a problem with the engine’s fuel system. It could also mean you have overfilled the engine or the oil is not flowing properly.
If excess oil is in the engine or the oil is not flowing through the engine as it should, it can be forced into the air filter box. This can cause problems like reduced engine performance and increased fuel consumption.
It is, therefore, important to address the issue as fast as possible to prevent potential engine damage.
Possible Causes of Oil in a Motorcycle Air Filter
Some of the potential reasons why there is oil in your bike’s air filter include the following:
Clogged Filter
A clogged filter can force oil into a motorcycle air filter by increasing pressure in the engine. When the filter is clogged, air cannot flow freely within the engine. The high pressure forces the oil out of the crankcase breather and into the air filter box.
This is how it happens:
The crankcase breather is an engine component that allows extra gases and pressure to escape.
If the filter is clogged, the pressure in the engine becomes too high and forces oil out of the crankcase and into the air filter box.
The oil can log the air filter, strict airflow into the engine, and cause performance problems.
Worn or Damaged Piston Rings
Piston rings seal the gap between the cylinder, wall, and piston to prevent oil from escaping into the combustion chamber.
When piston rings are damaged, they can’t maintain a proper seal, meaning oil can leak past them and into the engine’s combustion chamber.
In the combustion chamber, the oil is burned along with fuel contributing to excessive oil consumption. It can also accumulate in the air filter box and clog the filter element leading to reduced engine performance.
Overfilled Oil Tank
When the oil level in the tank is too high, the crankshaft can froth the excess oil to form foam. The foam can increase the pressure in the crankcase and cause oil to be forced out and into the air filter housing.
Damaged Airbox
The airbox houses the air filter and is located between a bike’s air intake and the engine. It is responsible for the steady supply of clean and filtered air to the engine.
If the airbox is damaged, it can allow oil to enter the filter, leading to oil buildup on the air filter.
Damaged Engine
Over time, engine components like gaskets and seals can get damaged, allowing oil to escape and end up in the air filter.
How to Fix Oil in the Air Filter
After identifying the cause of the oil in your motorcycle air filter box, solving the problem becomes extremely easy.
Suppose the issue is a clogged filter; cleaning or replacing the filter can fix the issue. Ensure regular maintenance of the engine to prevent future problems.
Replace worn-out piston rings as soon as possible if you suspect this to be the cause. This will help prevent oil leakage and further engine damage.
Solving the issue of an overfilled oil tank is the easiest. All you need to do is drain the excess oil to the correct level to prevent engine damage. Getting rid of the extra oil will also prevent oil from entering the air filter box.
And lastly, if you suspect the oil is leaking from the engine, inspect all gaskets and seals to ensure they aren’t damaged. Replace the damaged ones.
How to Prevent Oil Buildup in a Motorcycle Air Filter Box
To prevent oil buildup on the surface of the air filter box, consider the following:
- Avoid overfilling the oil tank by using the recommended oil level specified in the owner’s manual.
- Clean the air filter regularly to prevent dirt and debris from building up on the surface, leading to clogging.
- Carry out routine engine maintenance to ensure the engine is always well lubricated and serviced to prevent damage.
- Inspect the airbox occasionally and clean it regularly to prevent dirt and oil buildup on the surface.
Q. Is it normal for oil to be in the air filter?
No, it’s not normal for oil to be in a bike’s air filter. The air filter is designed to filter dust, dirt, and debris from the air before it enters the engine.
The presence of oil in the air filter means there is a problem with some of your engine’s components (piston, fuel injectors, etc.) or ventilation system that needs to be addressed.
Q. What are the consequences of oil in a motorcycle air filter?
Oil on the surface of the air filter can cause several problems, including reduced engine performance and power output, increased fuel consumption, and reduced efficiency and difficulty in starting the engine.
A motorcycle with oil in the air filter can also produce excessive emissions or fail emissions tests. In the worst-case scenario, it can cause engine damage.
Q. Can oil in the air filter cause engine to stall?
Oil in the air filter can restrict the flow of air into the engine, causing several issues, including stalling and rough idling.
Additionally, air in the filter can cause the engine to run rich, which means that there is excess fuel but not less air in the combustion chamber. This situation can lead to incomplete combustion and cause the engine to stall.
Q. Is it easy to clean a motorcycle air filter?
Cleaning a motorcycle air filter can be easy, depending on the filter installed on the bike. Consider the following steps when cleaning the filter:
- Remove the air filter from the air filter box or air intake box
- Inspect the filter for excessive dirt, debris, or damage. If damaged, get a replacement.
- Clean the air filter if it is only dirty but not damaged. You will require a cleaning solution for motorcycle air filters, warm soapy water, or compressed air.
- Follow the cleaning instructions from the manufacturer’s manual.
- After cleaning the air filter, leave it to dry completely before reinstalling it on the bike. Avoid using a heat source to dry the filter; this process can damage it.
- Reinstall the air filter in the air filter housing and ensure that it is properly seated and secured.
Q. When should I change the motorcycle air filter?
The frequency of changing the filter depends on several factors, such as the type of bike, how often you ride it, and the owner’s recommendations.
Generally, it is recommended that you check the air filter every 3,000 to 5,000 miles and change it every 10,000 to 15,000 miles or more frequently if you mostly ride on dusty roads.
Q. Can a bike still run with oil in the air filter?
Although a bike can still run with oil in the air filter, it is not recommended. If you notice oil in the bike’s air filter, you should have it inspected by a qualified mechanic as soon as possible.
Oil in the motorcycle’s air filter could indicate a problem with the oil system or a faulty PCV valve.
Q. Is it safe to ride a bike with oil in the air filter?
It is safe to ride a bike with oil in the air filter. However, you want to avoid riding your bike in this situation as it can lead to engine damage, which is expensive to repair.
