Crankcase Ventilation System Description

Engine Mechanical - 5.3L L84 or 6.2L L87 | Description and Operation | Document ID: 5022853 Crankcase Ventilation System Description (L82, L84) A closed crankcase ventilation system is used in order to provide a more complete scavenging of the crankcase vapors. Fresh air from the throttle body is supplied to the crankcase, mixed with blow-by gases, and then passed through a crankcase flow-controlled ventilation fitting into the intake manifold. The primary control is through the crankcase ventilation fitting located in the front of the left rocker arm cover. This fitting is equipped with a flow control nozzle which meters the air flow at a rate depending on manifold vacuum. To maintain idle quality, the flow control nozzle restricts the flow when intake manifold vacuum is high. If abnormal operating conditions arise, the system is designed to allow excessive amounts of blow-by gases to back flow through the crankcase vent tube into the engine air inlet to be consumed by normal combustion. Filtered fresh air is routed from the air inlet system to the front of the right rocker arm cover via a formed nylon tube. To reduce the potential of oil pullover due to back flow of the ventilation system, the fittings in the rocker arm covers are shielded from the rocker arms. From there fresh air and gases are routed through the crankcase and up through a metered PCV fitting on the front of the left rocker arm cover. Foul air is then routed into the left side of the intake manifold via a formed nylon tube. Crankcase Ventilation System Description (L87) A closed crankcase ventilation system is used in order to provide a more complete scavenging of the crankcase vapors. Fresh air from the throttle body is supplied to the crankcase, mixed with blow-by gases, and then passed through a crankcase flow-controlled ventilation fitting into the intake manifold. The primary control is through the crankcase ventilation fitting located in the front of the left rocker arm cover. This fitting is equipped with a flow control nozzle which meters the air flow at a rate depending on manifold vacuum. To maintain idle quality, the flow control nozzle restricts the flow when intake manifold vacuum is high. If abnormal operating conditions arise, the system is designed to allow excessive amounts of blow-by gases to back flow through the crankcase vent tube into the engine air inlet to be consumed by normal combustion. Filtered fresh air is routed from the air inlet system to the front of the right rocker arm cover via a formed nylon tube. To reduce the potential of oil pullover due to back flow of the ventilation system, the fittings in the rocker arm covers are shielded from the rocker arms. From there fresh air and gases are routed through the crankcase and up through a metered PCV fitting on the front of the left rocker arm cover. Foul air is then routed into the front of the intake manifold via a formed nylon tube.