Crankcase Ventilation Hose
A hose that carries blow-by gases from the crankcase to the PCV valve or the air intake system.
The crankcase ventilation hose is a rubber line that connects the engine block or valve cover to the PCV valve or the air intake duct. It is a critical component of the Positive Crankcase Ventilation (PCV) system, designed to route blow-by gases out of the engine crankcase.
Blow-by gases consist of unburned fuel and exhaust that leak past the piston rings. The ventilation hose carries these gases to the intake system so they can be burned in the cylinders, preventing pressure buildup that would blow out engine seals and cause oil leaks.
Because the hose carries oil vapor and fuel fumes, the rubber can become soft, spongy, or brittle over time. A cracked or collapsed ventilation hose can cause vacuum leaks, leading to a rough idle, high oil consumption, and engine sludge buildup.
Replacing a damaged crankcase ventilation hose is a simple and inexpensive maintenance task that restores proper PCV system operation and prevents oil leaks.