Installing a Valve Cover Breather:What Are Pros & Cons
A valve cover breather serves as a vital vent for your engine’s internal crankcase pressure.Every internal combustion engine generates “blow-by” gases during the power stroke.These gases escape past the piston rings and enter the crankcase.If this pressure has no exit,it will eventually force oil through your gaskets and seals.Consequently,engineers developed ventilation systems to manage this invisible force.While modern cars use complex PCV systems,many enthusiasts still turn to a traditional engine valve cover breather.In this article,we will explore its history,function,and the trade-offs of using one.
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What Exactly Is a Valve Cover Breather?
To understand the valve cover breather,you must first look at engine basics.It is a simple,filtered cap that replaces or sits alongside a PCV valve.Its primary job is to allow air to flow in or out of the crankcase.This prevents a vacuum or pressure buildup that could damage internal components.Most breathers feature a small,pleated filter or a mesh screen inside a chrome or plastic housing.Therefore,it protects the engine from dust while letting it “breathe” freely.
The Purpose Behind the Valve Cover Breather Invention
Engineers originally invented the valve cover breather to solve the problem of catastrophic seal failure.In the early days of motoring,engines simply vented these gases into the atmosphere through a draft tube.However,these tubes were inefficient at low speeds.The valve cover breather offered a more controlled way to balance internal pressure.It ensured that the engine did not turn into a pressurized bomb of hot oil and gas.Over time,it became a staple in both racing and daily driving applications.
Evolution of Crankcase Ventilation Systems
| Era | System Type | Primary Function | Environmental Impact |
|---|---|---|---|
| Pre-1960s | Road Draft Tube | Gravity-based venting | High (Oil dripped on roads) |
| 1960s – Present | Valve Cover Breather | Pressure equalization | Moderate (Filter traps soot) |
| Modern Day | Closed PCV System | Vacuum-assisted recycling | Low (Vapors are burned) |
| High Performance | Catch Can + Breather | Maximum filtration | Low/Moderate |
Top Benefits of Using a Valve Cover Breather
There are several functional reasons to install a valve cover breather on your vehicle.First,it effectively relieves high-pressure spikes that occur during heavy acceleration.This is especially true for turbocharged or supercharged engines.These “forced induction” systems create significantly more blow-by than standard engines.Second,a breather can help keep your intake manifold cleaner.By venting gases directly,you prevent oily mist from entering the throttle body.Consequently,your intake valves stay free from carbon buildup for a longer period.
Protecting Your Gaskets and Seals
A high-quality valve cover breather acts as a safety valve for your engine’s delicate rubber seals.When pressure builds up,the oil seeks the easiest path out.Usually,this means your cam seals or oil pan gasket will start to leak.By providing an easy exit through the breather,you keep the internal pressure at zero.This simple modification can extend the life of your engine gaskets by several years.Furthermore,it gives your engine bay a classic,high-performance aesthetic.
Performance Pros of Installing a Breather
| Benefit | How It Works | Best For |
|---|---|---|
| Pressure Relief | Allows gases to escape instantly | Turbo/Supercharged engines |
| Cleaner Intake | Stops oil from entering the air intake | Direct injection engines |
| Seal Longevity | Keeps crankcase pressure neutral | High-mileage vehicles |
| Visual Appeal | Adds a custom “racing” look | Show cars and hot rods |
Potential Downsides of the Valve Cover Breather
Despite the benefits,a valve cover breather is not a perfect solution for every car.The most significant drawback involves modern “metered air” systems.Most cars built after 1990 use a Mass Air Flow (MAF) sensor to measure incoming air.If you add a breather,air can enter the engine without passing the sensor.This creates “unmetered air” leaks,which cause the engine to run lean.Consequently,you might experience a rough idle or a “Check Engine” light.
Environmental and Cleanliness Issues
Another downside of a valve cover breather is the potential for an oily mess.Since the breather vents directly to the atmosphere,a small amount of oil mist may escape.Over time,this mist coats your valve cover and surrounding engine components in a sticky film.Additionally,this system is not environmentally friendly.It releases raw hydrocarbons into the air instead of burning them in the combustion chamber.Therefore,many states with strict emissions laws do not allow open breathers on street-legal cars.
Common Issues and Fixes
| Problem | Cause | Solution |
|---|---|---|
| Oily Residue | Oil mist escaping the filter | Add a baffle or use a catch can |
| Rough Idle | Unmetered air entering the system | Tune the ECU or use a closed breather |
| Smell of Oil | Vapors entering the cabin vents | Relocate the breather or check seals |
| Emissions Failure | Open venting of gases | Revert to a closed PCV system for tests |
How to Install Your Valve Cover Breather Properly
If you decide to install a valve cover breather,you must do it correctly to avoid problems.First,identify if your engine uses a MAF sensor or a MAP (Manifold Absolute Pressure) sensor.MAP-based engines handle breathers much better than MAF-based engines.Next,ensure the breather has an internal baffle.A baffle is a small metal plate that prevents liquid oil from splashing directly onto the filter.Without a baffle,your valve cover breather will become soaked in oil within minutes.
Maintenance and Cleaning Tips
You must treat your valve cover breather like any other air filter.Over several months,the filter element will become clogged with oily soot.A clogged breather is useless because it can no longer vent pressure.Therefore,you should clean or replace the filter every time you change your engine oil.Most high-performance breathers feature washable cotton elements.Use a dedicated filter cleaner,allow it to dry completely,and apply a light coat of oil if required.This ensures your engine remains protected and ventilated.
Expert Note:
Never block off your PCV system entirely without providing an alternative vent.Doing so will cause your dipstick to pop out or your seals to blow within miles of driving.
Finding the Right Balance for Your Vehicle
Choosing whether to use a valve cover breather depends on your specific goals.If you drive a modern daily commuter,stick with the factory PCV system.It is cleaner,quieter,and better for your fuel economy.However,if you have a high-horsepower track car,a breather is almost mandatory.It provides the high-volume venting that a standard PCV valve simply cannot handle.Many pro builders now use a “hybrid” system.They use a sealed catch can that vents through a valve cover breather only under extreme pressure.
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