Many vehicles manufactured today have an internal combustion engine equipped with a crankcase ventilation system. This is where the crankcase breather filter, also sometimes called the crankcase vent filter, is located. Typically, the breather filter is found more often on race cars, muscle cars, and motorcycles, but other vehicles including those with diesel engines may feature this part.

The purpose of the crankcase breather filter is to function as part of the crankcase system, working to filter contaminants out of the gases that are rerouted back to the engine. When this part malfunctions, there can be significant problems causes to the engine and its overall performance.

In this article, we will be giving you an idea of the symptoms you may encounter when the crankcase breather filter stops working properly. We’ll also give you an idea of replacement costs so you are fully informed and prepared to take care of this issue.

What Does a Crankcase Breather Filter Do?

All internal combustion engines will have some amount of blow-by, which is something that happens as the engine runs – pistons push gas into the crankcase, causing a build-up of pressure. This excess pressure can create issues with running the engine, so the crankcase ventilation system helps to relieve this pressure by either releasing the extra gas into the environment or rerouting it back to the engine for use.

As the excess gas makes its way back to the engine via a PCV valve, it may pick up debris, oil particles, or other contaminants. The crankcase breather filter is responsible for filtering out these elements and allowing the engine to continue functioning normally.

When the crankcase breather filter gets clogged or is otherwise nonfunctional, a number of problems may arise in the engine such as poor performance and oil leaks. It is important that the breather filter stays in good shape, much like any other filter in your car, to prevent any of these issues from occurring.

Where Is the Crankcase Breather Filter Located?

To find the crankcase breather filter for inspection, you will need to look on top of the crankcase in your engine. The filter is typically on top of the valve cover or attached to the breather hose that connects to the air intake. This area of the engine is also where pressure is released and air intake occurs.

Symptoms of a Bad Crankcase Breather Filter

A bad crankcase breather filter can cause serious problems for your car if left untreated. Below, we list some important symptoms to take note of if you suspect that your crankcase breather filter is not functioning properly.

Oil Leaks

Oil leaks are typically the first sign of a clogged or faulty crankcase breather filter. As the filter’s primary job is to prevent debris and contaminants from entering into the engine at the same time as relieving pressure, it is easy for the filter to become clogged or blocked. Once blocked, there is a higher chance for pressure building up in the engine, which is something that can lead to gaskets and seals being blown, resulting in oil leaks.

If you see oil leaking from your engine or notice puddles of oil underneath your car, it is a good idea to take your car to a professional to get it evaluated as soon as possible.

Why Is There Oil Coming Out of the Crankcase Breather?

In certain cases, you may also notice engine oil coming directly out of your crankcase breather filter. This is typically caused by worn-out seals creating pressure build-up; the pressure build-up pushes oil back and out of the breather filter. This can be a major source of oil leaks and may lead to a serious engine problem if left unaddressed.

Rough Engine Idle

When the crankcase filter becomes clogged or blocked with debris, it can create a rough engine idle. It may also create a change in idling speed; if your vehicle has developed a high idling speed, there may be a serious issue with a blocked breather filter or leaking oil in your engine.

Poor Engine Performance

A decrease in your engine’s performance is another symptom indicative of a faulty or blocked crankcase breather filter. Once the filter because clogged, it is difficult for air to pass through, causing issues with the pressure in your engine and a disturbance to the important air-fuel ratio.

If the air-fuel ratio is imbalanced, your car may experience a decrease in power and acceleration, especially when driving at low speeds.

However, poor engine performance can be caused by a number of other vehicle issues, so it is important to get this symptom properly diagnosed to figure out whether or not your crankcase breather filter is causing the problem or not.

Crankcase Breather Filter Replacement Cost

How much you pay for a crankcase breather filter replacement depends on your car’s model and the specific variation of where your crankcase breather filter is found in your car. There may be variable engine designs, materials, or mounting features that can cause a significant range of prices when it comes to purchasing this part and replacing it.

In general, the crankcase breather filter is a simpler part to replace, so you will likely not need to pay too much in terms of labor costs. On average the filter will only cost you between $20 and $100, while labor costs can range anywhere between $60 and $200. This means that the overall replacement costs for a bad crankcase breather filter will range anywhere between $80 and $300.

Keep in mind that local or independent mechanics will likely be able to replace this part for a cheaper cost than you would receive if you visited a dealership for this repair.

Can You Replace the Crankcase Breather Filter at Home?

Replacing your crankcase breather filter yourself is fortunately not a very hard repair. Even individuals who do not have a lot of experience DIYing their cars should be able to manage this replacement without too much stress. This article can help you get started on an at-home crankcase breather filter repair.

Completing this repair at home can help you save money on labor costs, though you will still need to purchase the replacement part. However, it is important to note that you should be totally sure that the breather filter is causing your car’s problems before starting a repair on it; if you are unsure, consult with a mechanic to get your vehicle’s issues fully diagnosed before deciding how to proceed about a repair.

Keeping Your Car in Top Shape

Experiencing issues with your car’s crankcase breather filter can be highly stressful and come with the worry of replacement costs and other repair issues. Fortunately, this essential part of your car’s crankcase ventilation system is not too difficult to repair and can be replaced either by a professional or at home for a reasonable cost.

If you are encountering any of the symptoms on our list, make sure you take your vehicle to be properly diagnosed by a professional to confirm the issue as soon as possible. From there, you can make an informed choice about repairs and be on your way to keeping your car in top shape.