Engine Crankcase Vent Hose (Blow-By Line)

This hose is a key part of the crankcase ventilation system. It is needed to route oily blow-by vapors from the engine crankcase back to the intake path, where they can be burned again instead of building pressure inside the engine. A healthy ventilation line helps keep seals safe, reduces sludge, and supports stable idle and clean running. ✅

How It Works ⚙️

During combustion, a small amount of gas escapes past piston rings into the crankcase. This hose carries those vapors through the ventilation circuit so the intake vacuum can pull them in a controlled way. The material is oil-resistant and heat-tolerant to survive engine bay temperatures and constant vapor flow.

When the Hose Is Damaged

If cracked, loose, or collapsed, the engine can develop vacuum leaks or excessive crankcase pressure. You may notice rough idle, whistling sounds, oil seepage from gaskets, higher oil consumption, and dirty intake piping. In severe cases, pressure can push oil past seals and shorten engine life.

Common Signs to Check

• Oil mist around the hose ends
• Soft, swollen rubber or splits
• Idle hunting / unstable RPM
• Burnt-oil smell near the engine

Compatibility ✅

• Navara
• Frontier
• Xterra
• Nv
• Pathfinder
• Nv3500
• Patrol