Internal combustion engines generate a variety of byproducts during operation, including unburnt fuel, oil vapors, and other contaminants. These substances can accumulate in the engine's crankcase and valve covers, leading to performance degradation and potential damage over time. A catch can is a device designed to intercept and separate these contaminants from the air before it is either recirculated into the engine or expelled to the atmosphere. This article provides an in-depth overview of catch can installation, focusing on the different types of catch cans, the removal of the original PCV system, and best practices for maximizing efficiency and engine longevity.
Understanding the Role of a Catch Can
A catch can is a critical component in the ventilation system of an internal combustion engine. It functions as an intermediate reservoir that captures and separates oil and fuel vapors from the air before it is either vented to the atmosphere or returned to the engine. The primary purpose of a catch can is to prevent oil and fuel from re-entering the combustion chamber, where they can contribute to carbon buildup, reduced fuel efficiency, and increased emissions.
There are three primary types of catch cans, each with distinct advantages and limitations:
- Standard Catch Can: This type of catch can collects and separates oil and fuel vapors from the air and recirculates the cleaned air back into the turbo intake pipe (TIP). It is the most commonly recommended option for performance and emissions control.
- Vent to Atmosphere: As the name suggests, this type of catch can vents the separated contaminants directly into the atmosphere rather than recirculating them. While it may simplify the system, it is not ideal for emissions compliance in regulated environments.
- Oil to Sump: This type of catch can returns the separated oil and fuel mixture back into the engine's sump. However, this approach has been largely abandoned due to concerns about condensation and oil dilution, which can negatively impact engine performance and longevity.
Each type of catch can has its own set of installation requirements and considerations. The choice of catch can should be based on the specific needs of the engine, the vehicle's intended use, and local emissions regulations.
Types of Catch Can Configurations and Their Features
A well-designed catch can should be equipped with internal baffling or filtering systems to effectively separate oil and fuel from the air. The efficiency of a catch can depends on the design of its internal components, including the number of inlets, the size of the baffled chambers, and the type of filters used. Some catch cans are atmospheric, relying solely on gravity and airflow to separate contaminants, while others are vacuum-assisted, using engine vacuum to enhance the evacuation process.
A high-efficiency catch can typically includes multiple inlets from the crankcase and valve covers, directing the contaminated air into baffled chambers. The air then passes through a filtering system before being vented or recirculated. Vacuum-assisted catch cans can use smaller-diameter tubing (e.g., -6AN or 3/8ā) due to the enhanced vacuum effect, whereas atmospheric catch cans may require larger tubing (e.g., -10AN or -12AN) to ensure adequate flow.
One common misconception is that any empty can or reservoir can function as a catch can. However, a proper catch can must include some form of internal aerator or baffling system to separate the oil from the air. Without these components, the catch can will not perform as intended and may allow contaminants to pass through unfiltered.
Installation Process: Removing the Original PCV System
Before installing a catch can, it is necessary to remove or modify the original PCV (Positive Crankcase Ventilation) system. The PCV system is responsible for managing the flow of gases from the engine's crankcase and valve covers. While the PCV system is effective in stock form, it can be simplified and optimized with the addition of a catch can.
The installation process typically involves the following steps:
- Disconnecting the Brake Servo Line: The first step is to disconnect the brake servo line from the inlet manifold. This requires cutting the rubber that connects the line to the PCV vacuum line. Care must be taken to avoid damaging the original system, as it should be possible to revert to the stock configuration if needed.
- Removing the PCV Hose Clamps: The next step is to remove the one-time-use hose clamps that secure the PCV system. These clamps are typically located near the front of the engine and can be removed using cutting pliers or snips.
- Removing the CBV (Crankcase Breather Valve): The CBV is a 90-degree pipe located near the dipstick tube and oil filter housing. It is responsible for venting gases from the crankcase. This component must be disconnected or bypassed to accommodate the catch can.
- Routing the Lines to the Catch Can: After removing the original PCV components, the next step is to route the vacuum lines from the valve covers and crankcase to the catch can. The lines should be at least -10AN in size, with a larger -12AN line used for the inlet to ensure proper flow.
It is important to note that the installation process may vary depending on the specific engine and vehicle configuration. For example, right-hand drive (RHD) vehicles may have components located on the opposite side of left-hand drive (LHD) vehicles. Therefore, it is essential to consult the vehicle's manual or a reliable installation guide before proceeding.
Best Practices for Maximizing Catch Can Efficiency
To ensure optimal performance, it is important to follow best practices when installing and configuring a catch can. These practices include:
- Using a High-Capacity Catch Can: A large catch can with multiple inlets and baffled chambers can significantly improve efficiency by allowing more time for the oil and fuel vapors to settle before the air is vented or recirculated.
- Routing the Lines Properly: The vacuum lines should be routed from the valve covers and crankcase to the catch can using -10AN or -12AN tubing. This ensures adequate flow and minimizes the risk of clogging or pressure buildup.
- Installing a Vacuum-Assisted System: A vacuum-assisted catch can can enhance the evacuation process by using engine vacuum to draw air through the system. This is particularly effective in turbocharged or supercharged engines.
- Using High-Quality Filters: The filters within the catch can should be of high quality to ensure that all contaminants are effectively separated from the air. Some catch cans may require periodic filter replacements, so it is important to check the manufacturer's recommendations.
By following these best practices, users can ensure that their catch can system is both effective and reliable. A well-designed and properly installed catch can can significantly improve engine performance, reduce emissions, and extend the life of the engine.
Maintenance and Troubleshooting
Once installed, a catch can requires regular maintenance to ensure continued performance. The frequency of maintenance will depend on the type of catch can and the operating conditions of the vehicle. For example, vehicles that are driven in stop-and-go traffic or under heavy load may require more frequent maintenance than those driven primarily on open roads.
Key maintenance tasks include:
- Draining the Catch Can: The catch can should be periodically drained to remove the accumulated oil and fuel mixture. This is typically done by unscrewing the drain valve at the bottom of the can.
- Inspecting the Filters: The filters inside the catch can should be inspected for signs of clogging or wear. If necessary, they should be cleaned or replaced according to the manufacturer's instructions.
- Checking for Leaks: The vacuum lines and fittings should be inspected for leaks, which can reduce the efficiency of the catch can and allow contaminants to pass through unfiltered.
If the catch can is not functioning as expected, users may experience symptoms such as reduced engine performance, increased emissions, or the presence of oil in the intake system. In such cases, it is important to inspect the catch can and its components for signs of wear, clogging, or improper installation.
Conclusion
A catch can is an essential component for managing the ventilation of internal combustion engines. By intercepting and separating oil and fuel vapors from the air, a catch can can significantly improve engine performance, reduce emissions, and extend the life of the engine. There are several types of catch cans available, each with its own advantages and limitations. The installation process involves removing or modifying the original PCV system and routing the vacuum lines to the catch can. Following best practices such as using a high-capacity catch can, routing the lines properly, and using high-quality filters can ensure optimal performance. Regular maintenance is also important to ensure continued functionality. By understanding the role of a catch can and following proper installation and maintenance procedures, users can ensure that their engine operates efficiently and reliably.