PCV / Crankcase Oil Breather System

The mountune Oil Breather System is the most functional and seamlessly integrated kit available on the market for all Mk7 Fiesta ST.

Based on the market-leading Radium kit, the mountune exclusive version further upgrades this premium oil breather system by replacing all oil hoses with high-quality braided black race versions, utilising Aeroquip-style black anodised race fittings throughout for the ultimate performance and packaged installation.

The oil breather kits are available as a combined kit including both a PCV side and Crankcase side system.

They do NOT vent to atmosphere (VTA), so comply with most basic emission requirements and are safe to use on the race track too.

The mountune Radium breather system removes the oil and sludge from the PCV gasses before it's routed to the engine to be burned. A closed loop system, like this, also promotes negative crankcase pressure for optimal performance. Furthermore, closed systems prevent unwanted oil vapors from entering the cabin.

The dipsticks built into the catch cans allow easy inspection of accumulated fluid and require no cutting, drilling or permanent modification to the vehicle during installation.


  • Effectively raises the octane and increased engine performance from cleaner inlet air
  • Prevents oil buildup in the intake and intercooler system walls, throttle body, intake manifold, etc.
  • Lowers hydrocarbon emissions
  • Capacity: 170ml each
  • Provides early indication of potential engine damage 
Each kit features the following:
  • Anodised oil catch can with integrated condenser and dipstick
  • Anodised aluminum Fiesta specific mounting bracket
  • Anodised aluminum Aeroquip style race fittings and high-performance lines
  • Stainless steel mounting hardware

PCV Breather Kit - secures to the front offside engine mount and the entire kit fits under the OEM engine cover with no modifications required. This catch can runs inline with the PCV (positive crankcase ventilation) valve and retains it's factory function. When the intake manifold pressure is close to or greater than atmospheric pressure, the PCV "check" valve closes and, thus, this hose experiences no flow.

Conversely, the PCV hose will experience "metered" vacuum when the engine is idling, steady state cruising, and decelerating. This would normally draw unwanted crankcase vapour, unspent fuel, and oil sludge into the intake manifold immediately after a high load run. Because the Radium catch cans are pressure sealed, they are great for turbocharged applications, so intake manifold connection is permitted.

Crankcase Breather Kit - secures to the 2 ECU mounting studs in the back nearside of the engine bay via a bespoke mountune catch can mount, enabling installation on all EU-build cars running a Thatcham ECU shield.

The entire kit fits under the OEM engine cover with no modifications required. This catch can runs inline with the crankcase vent port. At low loads it experiences atmospheric pressure, but when the engine is at high load (WOT), this hose will experience high flow out of the crankcase. This would normally lead to oil and sludge accumulation in the air filter intake pipe. Oil accumulation will occur in the intercooler which lowers the thermal efficiency properties of the heat exchanger and leads to decreased performance.

Kit option

Customer Reviews

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    United Kingdom United Kingdom

    Amazing Quality

    Yet again Mountune deliver. The dual kit really is great and very easy to install. Quality is amazing as always. Yet to see the results in terms of oil removed from the system etc but instantly notice the difference. No smell on hard pulls/high heat anymore. The only issue i had was connecting the crankcase to the mountune high flow aluminium induction is a very tight fit and took a few forceful attempts to finally get it to click into place. Other than that it’s an amazing product. Had I taken a little more time i wouldn’t have used tools that so easily scratch the system but was rushing as it started to rain so please bare that in mind when installing! Use care not to scratch!

    Phil D.
    United Kingdom

    Oil breather kit

    Top quality as usual,can’t wait to fit it

    Niel A.
    United Kingdom

    PCV System

    Amazing build quality on this kit, from the aero-style hoses through to the mounting bracket and the catch can itself. Way better than the equivalent Mishimoto oil catch can - not the cheapest but worth every penny in my opinion.

    Niel A. verified customer review of PCV / Crankcase Oil Breather SystemNiel A. verified customer review of PCV / Crankcase Oil Breather System