SKU: 7375987926

034Motorsport PCV Breather Hose - Audi / EA839 / 2.9T / 3.0T

Sale price$161.35 Regular price$179.28
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Description

034Motorsport PCV Breather Hose - Audi / EA839 / 2.9T / 3.0TUpgrade your factory corrugated plastic, failure prone PCV breather hose with the high performance, reliable 034Motorsport PCV Breather Hose, engineered for enhanced durability and long lasting performance. The PCV, or Positive Crankcase Ventilation system, on the EA839 is located on bank 2 of the engine (The right side of the engine). It is designed to ventilate the engine's positive crankcase pressure through the breather hose into the intake tract

Upgrade your factory corrugated plastic, failure-prone PCV breather hose with the high-performance, reliable 034Motorsport PCV Breather Hose, engineered for enhanced durability and long-lasting performance. 

The PCV, or Positive Crankcase Ventilation system, on the EA839 is located on bank 2 of the engine (The right side of the engine). It is designed to ventilate the engine's positive crankcase pressure through the breather hose into the intake tract or charge air system. The breather hose plays an integral role in this ventilation system, which uses two check valves to control the flow of crankcase pressure.

How Does the PCV System Operate?

The Positive Crankcase Ventilation System on the EA839 works to remove excess pressure from the crankcase system and relies on the vacuum from the engine’s intake system to operate properly. At idle or cruising while not in boost, the engine’s charge air system operates under vacuum, drawing air in continuously. During this state, the PCV system utilizes this vacuum to release crankcase pressure into the charge air system through the connection just after the throttle body.

However, when the vehicle is under boost (during acceleration), this connection becomes pressurized, meaning it can no longer provide a vacuum source for crankcase ventilation. When this happens, a check valve in the breather hose closes off this connection, preventing boost pressure from entering the crankcase. At this point, the breather hose is able to draw vacuum from the turbo inlet connection, as this creates vacuum through a siphoning effect as the turbocharger draws air in through the intake.

Whether you are sitting at a stoplight or romping on a backroad, a properly operating PCV system is crucial for maintaining the engine’s performance and preventing harmful pressure buildup.

Why is the OE PCV System Insufficient?

The check valves within the factory breather hose are an integral component of ensuring correct operation. However, since these check valves deal with the high temperatures of an engine bay and the transition between vacuum and boost pressure, they are susceptible to premature failure. When they fail, excess pressure can enter the crankcase, causing it to operate under conditions it was not designed for. In fact it’s likely these are the same as what Audi uses on naturally aspirated engines, which makes them not up to the task of dealing with pressures associated with turbocharged engines.

As the crankcase of the engine is not designed to operate under pressure, it typically will find the path of least resistance to release this excess pressure. The seals and components inside your engine, which are designed to operate under vacuum, aren’t built to handle this excess pressure. In some cases, the path of least resistance is unfortunately the oil cap, which can loosen and expel hot oil into the engine bay, potentially causing a fire.

Audi issued a TSB (Technical Service Bulletin) concerning this failure of the PCV Breather Hose as of 2020, though in our testing 034Motorsport has concluded that even the newest variant of breather hose is susceptible to failure.

Some other solutions on the market neglect the importance of maintaining adequate vacuum pressure from the charge air system and intake tract to ensure proper operation of the PCV system. Because the PCV system relies on these two separate vacuum sources under normal operation, removing one would prevent the crankcase ventilation system from functioning properly.

When these solutions remove the intake tract as a vacuum source, it disrupts the PCV system’s ability to vent crankcase pressure at idle or in a cruising state while not in boost. Because the crankcase no longer has sufficient vacuum pressure, seals that are designed to operate with this vacuum pressure can fail prematurely. This lack of vacuum pressure can also lead to the potential of pressurization of the crankcase system and engine damage.

Additionally, many aftermarket solutions have check valves that do not provide sufficient flow to accommodate the boost levels of Stage 3 equipped vehicles. These check valves are too small and this inefficiency can cause restrictions, resulting in reduced flow from the crankcase, causing crankcase pressure to build up. br*2 During the development of the 034Motorsport Stage 3 Dynamic+ tuning suite, the development B9 Audi S4 experienced an unfortunate OEM PCV breather hose failure.

This failure caused oil to be expelled through the oil cap and onto the hot turbocharger, immediately causing an engine oil fire. This failure was documented in our video Ashes to Asphalt, documenting the extent of the damage and how 034Motorsport was able to make the most out of the situation.

Because of this failure, it made engineering a proper solution that was able to withstand the harsh engine bay temperatures and elevated boost levels of utmost priority for 034Motorsport Engineers.

 

What is The Fix?

034Motorsport began by benchmarking the factory PCV system for flow capacity and other check valves on the market. Due to this, we opted to engineer and develop our own proprietary check valves that offer fantastic restrictionless-flow capability when open, and create a strong seal when closed, capable of holding over 40+ PSI of pressure and dealing with the high temperatures this system is subject to. These check valves utilize a durable synthetic rubber diaphragm that offers superior high heat and chemical resistance.

034Motorsport engineers designed the 034Motorsport PCV Hose to be used with the OEM Factory Air Oil Separator, as we found during testing that this unit provides excellent crankcase pressure control and is capable of supporting the flow needed at Stock through Stage 3 power levels without failure.

The 034Motorsport Check Valves are housed in a high-flow 4-ply reinforced silicone hose, specially designed to not collapse or inflate under vacuum or boost pressure. These silicone hoses are molded to allow for the factory engine cover to be utilized with the 034Motorsport PCV Breather System installed.

The 034Motorsport PCV Breather Hose uses OE-style multi-use connections, which allow for easy installation and removal when servicing your turbo inlet.

The OEM breather hose includes a new turbo inlet system as well, increasing the cost of this failure-prone component. whereas with the 034Motorsport PCV Breather System installed, there is no need for excessively costly OEM replacement components, as the 034Motorsport Breather Hose is engineered to last the lifetime of your vehicle.

The result is the 034Motorsport PCV Breather Hose, which isn’t just an upgrade for performance enthusiasts—it’s a critical safety enhancement for all EA839-equipped vehicles. It has been extensively tested on several 034Motorsport development vehicles for upwards of 2 years at varying power levels to ensure its performance and reliability, whereas the OEM breather hose can fail in as little as 3 months! The 034Motorsport PCV Breather Hose is suitable for all vehicles including those that are bone stock or upgraded with Dynamic+ Stage 1, 2, or 3 tuning!

Features:

  • Direct Replacement of the Failure Prone OE PCV Hose
  • Ensures High Flow Crankcase Ventilation to Prevent Crankcase Pressurization
  • Eliminates Potential Boost Leak at OE Plastic Check Valve Housing
  • Supports Boost Pressures to 40+ PSI
  • Compatible with OEM and Upgraded Turbocharger Inlets
  • CNC-Machined, Billet Aluminum Check Valve Body (Black Anodized), with a Heat and Chemical Resistant, Durable Rubber Diaphragm
  • 4-Ply, Reinforced, Silicone Hose
  • Retains Factory Engine Cover
  • Simple Installation

EMISSIONS DISCLAIMER:

  • This product is sold for racing use as well as use on vehicles not registered for on highway use.
  • By purchasing this product, you understand that this product is sold for racing use as well as used on vehicles not registered for on highway use, and that it is not legal for use on highway or street vehicles.
Shipping Notes
  • Free Standard Shipping on $100+ Orders to the USA.
  • Except Preorder products are shipped in 48 hours.
  • Delivery to the USA:
  1. Standard Shipping : 3-10 business days
  • If time is of the essence, please consider selecting expedited delivery for faster service.
Exchange/Return Notes
  • We offer a 30-day return/exchange service after receiving.
  • Final sale items are not eligible for returns or exchanges.
  • To process your return/exchange, please contact us at [email protected]
  • Please click here for more details>>> Return & Exchange Policy
SKU: 7375987926

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4.6 ★★★★★
Based on 21 reviews
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Verified Purchase
USMC 79
Waukegan, US
★★★★★ 5
Works great,not for heavy oxidation
This stuff works great, but it's best to grab (Awesome) spray, to use as a first step. The yellow oxidation melts away on contact, then rinse your headlights thoroughly with water and micro rag dry. Then use the wipes that come in the box to clean the headlights thoroughly again, rinse with water. Once thoroughly rinsed and dried, apply the UV clear coat with simple left to right or right to left strokes. Let it dry and enjoy.
WAS THIS REVIEW HELPFUL?YesReportShare
Reviewed in the United States on May 19, 2026
J
Verified Purchase
Jocko Smarts
Lexington, US
★★★★★ 5
Good for the effort and price.
This will _NOT_ make your lights look brand new! It will make them clear again. Or mostly clear if your lights are super bad. I had one old light and one new light on my car when I bought it. It drove me crazy walking by my car. I used this exactly per instructions other than I rubbed the crap out of my light. I got great results! Not perfect though. I got two clear headlights now. That is what I wanted. The finish is a little rough. This is to be EXPECTED since you are not using buffing compound. Use gloves. The finish looks like a light is a few years old now instead of 15 years old. It will not be can not make your light look new. Get the expensive kit if you want new look. My lights look close enough to not catch the eye. I am satisfied.
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Reviewed in the United States on April 14, 2024
J
Verified Purchase
Jay S.
Natrona Heights, US
★★★★★ 4
Not bad at all!
These headlight cleaner wipes worked far better than I thought they would. I have used many a headlight cleaner and restorer, but this kit was the easiest to use with very good results. No need for power tools or even different sanding disks. Just two different types of wipes, super easy. We will see how long the lights stay clear for, but if I had to do it once a year it would be worth it! Four stars because the lights came out clear, but not crystal clear, but to be fair that may just be the condition of my headlights. Try this least expensive, easy fix first. It many very well be just what you need.
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Reviewed in the United States on December 14, 2025
D
Verified Purchase
DW95
Bozeman, US
★★★★★ 3
Worth it for $12.
Three stars for the progress it made on the lights of our 9 year old car. It works, but it won't look like new. Requires a bit of elbow grease, and it feels like a waste when the wipes run dry pretty fast. You have to keep them folded small (per the instructions) so they don't evaporate too fast, but then you get a tiny cleaning surface area as well. Spoiler alert: They still dry out fast. I wish I'd taken pictures for you because you WILL see a good improvement. Just don't expect brand new look. I'd say we had a maybe 75% improvement, and that combined with the new headlamps we installed made them work great. 4 stars if they want to come back and offer a like 2-4oz bottle of the chemical they use on the wipes and just let me use my own microfiber. That would be great.
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Reviewed in the United States on August 31, 2025
D
Verified Purchase
Diane K
Whiting, US
★★★★★ 1
Product doesn't work as advertised
This product does not provide enough wipes to remove more than the minimum amount of oxidation. The headlights were starting to yellow, so the oxidation was not severe. We followed the directions on the box to the letter and after using the wipes as directed were left with a sticky residue (which was left-over oxidation that the drying wipes could not remove). I am forced to purchase another box of the product in order to complete the job. I can't drive my car around with the tape protecting the body of the car on it, plus this is Florida so there would be bugs stuck in the tape and the sticky residue. A terrible product. Plus when I called them they said they would send me an email so I can tell them what the problem is and they would give it to their "research" staff to handle. I'm doing that and perhaps they will reimburse me for the second box I will have to get overnighted in order to finish the job.
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Reviewed in the United States on April 18, 2025

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