Buy Subaru Legacy PCV Valve Hoses

The PCV valve hose-also called a breather hose, vent tube, or crankcase vent line-lets a Subaru Legacy's engine pull oily blow-by gases from the crankcase back into the intake so they can be burned, cutting pollution and helping the engine last longer. (en.wikipedia.org, dieselnet.com) A fresh, flexible hose keeps air-fuel balance steady, prevents rough idling, and stops that hot-oil smell some drivers notice on high-milers. (static.nhtsa.gov, legacygt.com)

Inside every Legacy engine, pressure builds when combustion gases sneak past the piston rings. The PCV system uses manifold vacuum to draw those gases out through the hose and one-way PCV valve, lowering crankcase pressure and sending the fumes back to the intake for clean burn-off. (en.wikipedia.org, dieselnet.com) By recycling instead of venting, the hose helps meet federal crankcase-emission rules set by the U.S. EPA. (epa.gov)

On fourth- through seventh-generation Legacys the hose runs from the valve (threaded into the engine's plastic or aluminum separator cover) to a port on the intake manifold plenum or turbo inlet. (youtube.com, static.nhtsa.gov) Subaru uses heat-resistant rubber molded in a gentle S-curve so it won't kink under engine movement. Interior diameter is about 5∕8-inch (16 mm) on most 2.5-liter EJ and FB engines. (forums.nasioc.com)

• Whistling or hissing-air leaks through splits in the hose, making a vacuum whistle. (reddit.com)
• Check-engine codes such as P0171 (system too lean) or P0507 (idle high) from extra un-metered air.
• Oil film around the crankcase or intake snorkel where fumes escape. (legacygt.com)
• Burning-oil smell or white smoke during warm-up-a noted issue Subaru addressed with an upgraded hose clamp and rubber compound. (static.nhtsa.gov, reddit.com)

• Typical hose I.D.: 16 mm (5∕8 in.) EJ/FB engines; 14 mm FA24 turbo. (forums.nasioc.com, static.nhtsa.gov)
• Material: oil-resistant nitrile or fluoroelastomer rated to 300 °F.
• Must seal tightly to hold 15-20 inHg manifold vacuum at idle. (dieselnet.com)

Subaru's maintenance poster lists PCV inspection every 30,000 mi (48 000 km); many owners replace the hose each second valve swap (≈60 000 mi) or any time it feels brittle. (subaru.ca, subaruoutback.org) Extreme heat or boosted engines may warrant earlier checks.

1. Disconnect the negative battery cable for safety.
2. Pinch spring clamps with pliers or release click-clamps.
3. Twist the old hose to break the seal, then pull straight off.
4. Seat the new hose fully; align so it clears the throttle body linkage.
5. Re-install clamps behind the factory bead to stop blow-off under boost. (youtube.com)
   Tip: Lightly coat fittings with fresh engine oil for easier sliding and a better seal.

• TSB 11-204-23 introduced a revised Legacy/Outback hose with stronger clamps to cure fuel-and-rubber odors. (static.nhtsa.gov)
• WUP-01R campaign (2019) required inspection for cracked PCV valves and hoses on certain 2017-18 models. (static.nhtsa.gov, repairpal.com)
  Staying current on bulletins helps avoid unexpected oil use and potential power loss.

A working hose keeps hydrocarbon-rich blow-by from venting to the air, reducing smog-forming emissions and oil mist that can harm sensors and cats. (epa.gov, innova.com)

Keeping the PCV hose soft, tight, and crack-free guards engine health, reduces emissions, and keeps your Subaru Legacy running smoothly for years to come. Spend a few minutes inspecting or replacing this small vent hose, and you'll dodge bigger repair bills down the road. (innova.com, legacygt.com)