Types of Valve Cover Breathers
A valve cover breather is a crucial component mounted on an engine's valve cover that allows the air and gases inside the crankcase to escape. This ventilation system helps prevent pressure build-up within the engine, which can lead to oil leaks, reduced performance, and increased emissions. By allowing controlled airflow in and out of the crankcase, the breather ensures proper engine operation and longevity. Over time, these breathers can become clogged with dirt, sludge, or oil vapors, reducing their effectiveness. Regular inspection and maintenance are essential to ensure optimal engine function.
Breather Filter
The standard breather filter serves as the primary means of crankcase ventilation in many engines. It typically includes a replaceable element made from foam, paper, or synthetic materials designed to trap contaminants while allowing clean air to pass through.
Advantages
- Effective filtration of airborne particles
- Helps maintain clean crankcase environment
- Easy to inspect and replace
- Cost-effective solution
Limitations
- Requires regular maintenance
- Less efficient under high-performance conditions
- May restrict airflow when dirty
Best for: Daily drivers, stock engines, general maintenance applications
Racing Valve Cover Breather
Designed specifically for high-performance vehicles, racing valve cover breathers offer superior airflow capacity and durability. These units often feature large-diameter openings and multi-layered filtration systems to handle the intense demands of competition engines.
Advantages
- High-flow design for improved ventilation
- Durable aluminum or billet construction
- Enhanced resistance to heat and vibration
- Customizable appearance options
Limitations
- Higher cost compared to standard models
- May require modification for installation
- Not ideal for everyday street use
Best for: Track vehicles, modified engines, motorsport applications
Oil Catch Can
An oil catch can works in conjunction with the valve cover breather system to capture oil vapors and particulates before they enter the intake system. This component is particularly beneficial for modern direct-injection engines where carbon buildup can be a significant issue.
Advantages
- Reduces carbon buildup on intake valves
- Improves airflow and combustion efficiency
- Protects engine components from oil contamination
- Extends service intervals between cleanings
Limitations
- Additional installation complexity
- Requires periodic draining and cleaning
- Increases overall system cost
Best for: High-mileage vehicles, turbocharged engines, direct injection setups
Push-in Valve Cover Breather
This type of breather offers a simple, plug-and-play solution for basic crankcase ventilation needs. Designed to fit into pre-existing grommet holes on the valve cover, it provides straightforward functionality without requiring modifications.
Advantages
- Easy installation with no drilling required
- Cost-effective replacement option
- Available in various sizes and styles
- Good for maintaining factory configuration
Limitations
- Limited customization potential
- May not provide sufficient flow for modified engines
- Potential for loosening over time due to vibration
Best for: OEM replacements, budget-conscious owners, standard engine builds
Screw-in Valve Cover Breather
Offering a more secure and customizable mounting option, screw-in breathers provide enhanced sealing capabilities. They require threaded installation but allow for greater flexibility in placement and orientation.
Advantages
- Secure, leak-proof connection
- Available in multiple thread sizes
- Improved airflow management
- Compatibility with aftermarket valve covers
Limitations
- More complex installation process
- Potential need for drilling and tapping
- Higher initial investment
Best for: Custom engine builds, performance upgrades, specialized installations
| Type | Installation Complexity | Flow Capacity | Filtration Efficiency | Ideal Application |
|---|---|---|---|---|
| Breather Filter | Low | Moderate | High | Stock engines, daily drivers |
| Racing Valve Cover Breather | High | Excellent | Moderate | Track vehicles, competition builds |
| Oil Catch Can | Moderate | Moderate | Excellent | Direct injection engines, performance cars |
| Push-in Breather | Very Low | Low | Moderate | OEM replacement, entry-level use |
| Screw-in Breather | Moderate to High | High | High | Custom builds, performance upgrades |
Expert Tip: For best results with any valve cover breather system, combine it with a properly functioning PCV (Positive Crankcase Ventilation) valve. This ensures balanced pressure regulation and prevents excessive oil consumption or blow-by issues.
Warning: Neglecting breather maintenance can lead to serious engine problems including oil leaks, power loss, and internal damage. Check your breather system during every oil change and replace or clean components as needed based on manufacturer recommendations.
Specifications and Maintenance of Valve Cover Breathers
Key Specifications to Consider
Valve cover breathers play a critical role in engine ventilation by allowing crankcase gases to escape while preventing contaminants from entering the engine. When selecting a valve cover breather, it's important to consider several key specifications that affect performance, compatibility, and durability.
Size and Fitment
The physical dimensions of a valve cover breather are crucial for proper installation and function. The size is typically determined by the diameter of the outlet pipe on the valve cover, which generally ranges between 1 to 2 inches. Ensuring an exact fit is essential to prevent leaks or improper sealing.
Inaccurate sizing can lead to vacuum leaks, oil blow-by, and potential damage to internal engine components due to increased crankcase pressure.
Material Composition
Valve cover breathers are commonly constructed from aluminum, steel, or high-temperature resistant plastic. Aluminum is the most popular material due to its excellent heat resistance, corrosion protection, and lightweight properties.
Steel offers enhanced durability in high-stress environments, while plastic models may be preferred for lightweight applications or aesthetic purposes. Choosing the right material depends on your vehicle’s operating conditions and intended use.
Filter Media Types
A valve cover breather includes a filtration system to trap dirt, debris, and oil vapors before they enter the intake system. Common filter media include stainless steel mesh, foam, and pleated paper elements.
Stainless steel mesh filters are reusable and offer excellent airflow but require regular cleaning. Foam filters provide good oil absorption and are often used in off-road or dusty environments. Paper filters are effective at capturing fine particles but are disposable and need periodic replacement.
Thread Pitch and Fitting Type
Most valve cover breathers come with brass fittings that allow them to connect securely to the engine’s PCV (Positive Crankcase Ventilation) system. Thread pitches vary depending on the engine design, with common sizes including 1/8", 1/4", and 3/8" NPT (National Pipe Taper).
Selecting the correct thread pitch ensures a leak-free connection and compatibility with your existing engine setup. Adapters may be available if you're upgrading or modifying the system.
| Specification | Importance | Selection Tips |
|---|---|---|
| Size Compatibility | High | Measure your valve cover opening and confirm matching thread size and diameter before purchasing |
| Material Quality | High | Choose aluminum or steel for high-performance engines; plastic works well for lighter-duty or cosmetic applications |
| Filter Efficiency | Medium-High | Opt for stainless steel mesh for reusability or foam for better oil retention in demanding conditions |
| Ventilation Capacity | Medium | Look for multiple vent openings and larger surface area designs to improve airflow efficiency |
Essential Maintenance Practices
To maintain optimal engine performance and longevity, regular maintenance of the valve cover breather is necessary. Proper care ensures consistent airflow and prevents harmful contaminants from entering the engine.
Important: A neglected or malfunctioning valve cover breather can lead to reduced engine performance, oil leaks, and even internal engine damage over time. Always address signs of wear or blockage promptly to avoid costly repairs.
How to Choose Valve Cover Breather
Selecting the right valve cover breather is essential for maintaining proper engine ventilation and performance. The correct breather ensures that crankcase pressure is effectively managed, reducing oil leaks, emissions, and wear while preserving engine longevity.
Material Selection
The material of a valve cover breather significantly affects its durability, heat resistance, and compatibility with various operating environments. Choosing the right material ensures long-term reliability and performance tailored to your specific application.
- Aluminum: Lightweight and corrosion-resistant, aluminum breathers are ideal for most street and mild-performance applications. They offer good thermal conductivity and are often anodized for added protection.
- Nylon: Economical and chemically resistant, nylon breathers work well in clean environments but can degrade under high-temperature conditions such as those found in racing or heavy-duty engines.
- Steel/Chrome: These provide excellent durability and heat resistance, making them suitable for harsher environments. Chrome-plated versions also add a polished aesthetic to engine bays.
Key consideration: For extreme temperatures or corrosive environments, opt for metal-based materials over plastic or nylon options.
Engine Type and Application
Different types of engines have varying requirements when it comes to crankcase ventilation. High-performance and forced-induction engines produce more blow-by gases and require more robust breathing systems than standard naturally aspirated setups.
- Street Vehicles: Typically benefit from moderate-flow breathers with filtration systems to keep intake air clean and prevent debris ingress.
- Race Engines: Require high-flow breathers without restrictive filters to allow rapid venting of large volumes of blow-by gases during intense driving conditions.
- Diesel Engines: May need specialized breathers due to higher volumes of oil mist and soot accumulation, which can clog standard units quickly.
Application tip: Always match breather flow capacity with engine output and operating intensity for optimal performance.
Size and Fitment
Valve cover breathers come in standardized sizes—most commonly 1-inch and 1.5-inch thread or flange diameters. Ensuring the breather matches the existing mounting hole on your valve cover (or using appropriate adapters) is crucial for a secure fit and leak-free operation.
- Measure the diameter of the existing breather hole or valve cover opening precisely before purchasing.
- Check if the breather includes any necessary adapters or O-rings for sealing purposes.
- Ensure compatibility with other components like PCV valves, catch cans, or vacuum lines in the system.
Installation advice: A properly sealed breather prevents oil leaks and maintains consistent crankcase pressure for better engine efficiency.
Filter Element Quality
The filter element inside the breather plays a critical role in preventing dirt, dust, and contaminants from entering the engine through the ventilation system. Selecting a breather with an effective filtration medium extends engine life and reduces maintenance intervals.
- Stainless Steel Mesh: Offers excellent durability and can be cleaned and reused multiple times. Ideal for high-performance or off-road vehicles where exposure to dirt is common.
- Brass Filters: More affordable but less durable over time. Suitable for basic street use where extreme contamination is unlikely.
- Foam Elements: Provide superior airflow but require regular cleaning and replacement to avoid clogging and restricted flow.
Maintenance note: Breathable filters that are washable and reusable offer long-term cost savings and environmental benefits.
Maintenance Tip: Regular inspection and cleaning of the breather element will ensure continued performance and prevent buildup of sludge or carbon deposits. If you notice signs of oil leakage around the breather mount or reduced engine responsiveness, it may be time to service or replace your breather unit.
| Application Type | Recommended Material | Typical Filter Type | Maintenance Frequency |
|---|---|---|---|
| Street daily driver | Aluminum | Stainless steel mesh | Every 15,000 miles or annually |
| Off-road vehicle | Steel or chrome | High-density foam | Every 5,000–10,000 miles |
| Race car | Aluminum or titanium | No filter (open flow) | After every race session |
| Diesel engine | Chrome-plated brass | Oiled foam or multi-layer mesh | Every 10,000 miles or sooner |
DIY Guide to Replacing Valve Cover Breathers
Replacing valve cover breathers is a straightforward maintenance task that can help maintain engine performance and prevent oil leaks. This DIY-friendly procedure typically takes less than an hour and requires only basic tools. Follow this detailed guide to safely replace your valve cover breathers at home.
Safety Reminder: Always allow the engine to cool completely before working on any components to avoid burns or injuries. Ensure your vehicle is stable and the ignition is off during the process.
Understanding Valve Cover Breathers
Valve cover breathers are essential for maintaining proper pressure balance in the crankcase by allowing controlled ventilation. Over time, these components can become clogged or damaged, leading to issues like increased emissions, oil leaks, or reduced engine efficiency. Regular inspection and timely replacement help ensure optimal engine function.
Tools and Materials Required
- Socket set (standard and deep sockets)
- Ratchet with extension (if needed for access)
- Torque wrench (to ensure proper bolt tightness)
- New valve cover breather(s) – OEM recommended or high-quality aftermarket
- Clean cloth or paper towels
- Drip pan (optional, in case of minor oil leakage)
- Replacement valve cover gasket (if necessary due to wear)
| Component | Purpose | Recommended Type |
|---|---|---|
| Valve Cover Breather | Allows crankcase ventilation while preventing contaminant entry | OEM or reusable metal/carbon filter units |
| Socket Set | For removing and reinstalling valve cover bolts | Standard and metric sizes as per vehicle specs |
| Torque Wrench | Ensures correct bolt tension to prevent warping or leaks | Click-type or digital torque wrench |
Step-by-Step Replacement Procedure
- Engine Cooling
- Turn off the engine and allow it to cool for at least 30 minutes to prevent heat-related injuries.
- Access the Valve Cover
- Open the hood and locate the valve cover(s), typically found on top of the cylinder head.
- Remove any covers, shields, or air intake components blocking access if necessary.
- Removing the Valve Cover
- Using a socket and ratchet, remove all bolts securing the valve cover to the cylinder head.
- Gently lift the valve cover straight up, being cautious not to damage the gasket or surrounding components.
- If the gasket sticks, carefully use a plastic scraper to separate it without scratching the metal surfaces.
- Replacing the Breather
- Locate the breather element on the valve cover—this may be a screw-in unit or a press-fit cap.
- Remove the old breather using appropriate tools or by hand if possible.
- Install the new breather by screwing or pressing it into place until snug. Avoid over-tightening unless specified.
- Reinstalling the Valve Cover
- Clean any residual oil or debris from the valve cover and cylinder head surface.
- If replacing the gasket, install a new one ensuring it's properly aligned.
- Lower the valve cover back onto the cylinder head and begin threading the bolts by hand to prevent cross-threading.
- Tighten the bolts evenly using a torque wrench to the manufacturer’s specifications (usually between 5–8 ft-lbs).
- Final Clean-Up and Inspection
- Wipe away any excess oil or residue from the work area and valve cover.
- Double-check that all bolts are torqued correctly and the breather is securely installed.
- Reconnect any disconnected components and close the hood.
Pro Tip: If you're unsure about the type of breather your engine uses, consult your vehicle's service manual or contact a dealership parts department. Some engines feature dual breathers or specialized designs that require specific replacements for optimal performance.
Post-Replacement Checks
After completing the replacement, start the engine and let it idle for a few minutes. Listen for unusual noises and inspect around the valve cover for any signs of leaks. Check the breather operation by ensuring there is no excessive pressure buildup when the engine is running.
Maintenance Note: It's a good practice to inspect your valve cover breather every 15,000 to 20,000 miles or during routine oil changes. Early detection of wear or blockage can prevent more serious engine issues down the road.
Valve Cover Breather: Frequently Asked Questions
The valve cover breather is an essential ventilation component in internal combustion engines, designed to manage airflow within the engine's valve cover. By allowing controlled air exchange, it prevents pressure buildup inside the valve cover chamber while expelling harmful vapors and moisture that could otherwise lead to oil contamination and corrosion.
This system plays a crucial role in maintaining optimal engine performance by:
- Reducing internal pressure that might cause oil leaks or gasket failure
- Preventing condensation buildup through proper ventilation
- Assisting in the removal of blow-by gases from the crankcase
- Promoting longer engine life by maintaining cleaner internal conditions
The valve cover breather is typically mounted directly on the top surface of the engine's valve cover, making it easily accessible for maintenance. Its position allows it to effectively ventilate the upper portion of the engine where combustion-related vapors tend to accumulate.
Depending on the vehicle make and model, the breather may appear as:
- A small plastic or metal cap with integrated filtration
- A standalone filter element connected via rubber hose
- An integrated part of the engine's Positive Crankcase Ventilation (PCV) system
In some modern vehicles, particularly high-performance or turbocharged engines, the breather system may be more complex, featuring multiple stages of filtration or connection to the intake manifold for vapor recirculation.
No, while both components are part of the engine's ventilation system, they serve distinct but complementary functions:
| Component | Primary Function | Key Features |
|---|---|---|
| Valve Cover Breather | Provides fresh air intake and ventilation for the valve cover area | Simple design with filtration media; often a passive system |
| PCV Valve | Regulates airflow between crankcase and intake manifold | Active valve mechanism; manages pressure under different engine loads |
Together, these systems work to maintain proper engine breathing, reduce emissions, and prevent oil contamination. While the breather focuses on the upper engine area, the PCV valve manages crankcase pressure and gas recirculation throughout the engine cycle.
While an engine can technically operate without a functioning valve cover breather, doing so compromises several critical aspects of engine health and performance:
- Pressure Buildup: Without proper ventilation, pressure accumulates in the valve cover, potentially causing oil leaks and gasket failure
- Moisture Accumulation: Condensation forms when moist air cannot escape, leading to sludge formation and accelerated wear
- Contaminant Infiltration: An open system without filtration exposes sensitive engine components to dirt and debris
- Performance Issues: Restricted airflow affects combustion efficiency and power output over time
Long-term operation without a functional breather can significantly shorten engine lifespan and increase maintenance costs. For optimal performance, always ensure the breather is installed and functioning properly.
Maintenance intervals for valve cover breathers vary depending on driving conditions and manufacturer recommendations, but general guidelines suggest:
- Visual inspection during every oil change
- Replacement every 30,000 to 60,000 miles under normal driving conditions
- Immediate replacement if signs of damage or clogging appear
Factors that may require more frequent replacement include:
- Frequent short trips that promote condensation buildup
- Driving in dusty or dirty environments
- High-performance applications with increased blow-by gases
- Modified engines with altered ventilation requirements
When replacing the breather, consider upgrading to high-quality OEM or performance-oriented units that offer better filtration and longevity. Always check local emission regulations when modifying or replacing factory-installed ventilation components.