What is a catch can?
Oil catch cans prevent oil and contaminants from being consumed by your vehicle, and also prevent build up which can contribute to other issues. The catch can is plumbed into the vehicle’s PCV (positive crankcase ventilation) system.
What is a PCV System?
The PCV system is designed to keep the air in the crank case fresh and free of contaminates, water vapor, etc. It does this by pulling fresh air from the intake tube or port on the throttle body that leads forward into the intake tube. This lets fresh air in. No oil is expelled into the intake tube. The contaminated air is then sucked into the intake manifold with a vacuum port somewhere after the throttle body. There is always a PCV valve used on this line. On late model LS motors it is either a PCV valve or a restricting orifice built into the drivers side valve cover or the valley cover (underneath intake manifold). On early model LS motors there is an external PCV valve located just left of the throttle body. This line is responsible for sucking up the crank case contaminates and water vapor. New Gen V LT1 based engines have a screw in PCV valve in the valley cover just to the right of the throttle body. A catch can on this line is extremely handy for stopping oil contamination from reaching the intake manifold.
Oil build up on the inside of the intake manifold can contribute to issues such as spark knock and poor driveability. LS motors are known for oil consumption especially, so having a catch can helps keep the car from constantly ingesting oil.
