Your 2009-2016 BMW Z4 Engine Crankcase Breather Hose: A Replacement Guide
Understanding the signs of a failing crankcase breather hose on your Z4 and how to choose the right replacement part.
- A cracked breather hose is a common issue that causes vacuum leaks, leading to rough idling and a Check Engine Light.
- Symptoms include a whistling noise from the engine, poor performance, and potentially new oil leaks.
- CRP/Rein is an OEM supplier, making their hoses a top-tier aftermarket choice that is often identical to the original part.
- While DIY replacement is possible, the hose connectors can be brittle and difficult to access, especially on N52 engines.
Is Your Z4's Breather Hose Failing?
The crankcase breather hose on your 2009-2016 BMW Z4 (E89) is made of plastic and rubber materials that are exposed to constant heat and oil vapors. Over time, these materials become brittle, leading to cracks and leaks. This is a common wear-and-tear item on BMWs, including the N20, N52, and N54 engines used in the Z4.
Common Symptoms of a Bad Breather Hose
🎬 Watch this video to learn more about common PCV symptoms.- Rough Idle: A cracked hose creates a vacuum leak, disrupting the air-fuel mixture and causing the engine to idle poorly.
- Check Engine Light: The vacuum leak can trigger diagnostic trouble codes, often for a lean fuel mixture (like P0171 or P0174).
- Whistling or Hissing Noises: Air being sucked through a crack in the hose can create a distinct whistling or hissing sound from the engine bay.
- Increased Oil Consumption: Improper crankcase pressure can lead to higher than normal oil consumption.
- Oil Leaks: When the system can't regulate pressure, it can force oil past gaskets and seals, causing leaks.
Choosing the Right Aftermarket Part
When it's time to replace the breather hose, you have options. While you can always get a Genuine BMW part from a dealership, high-quality aftermarket parts offer a great balance of performance and value.
Brand Tiers for Your BMW Z4:
- OEM Supplier (CRP/Rein): CRP, which markets its products under the Rein Automotive brand, is often the Original Equipment Manufacturer (OEM) for BMW's hoses. This means a Rein hose is frequently identical to the Genuine BMW part, sometimes even having the BMW logo ground off. For this reason, Rein is considered a top-tier choice that provides original quality without the dealership price tag.
- Reputable Aftermarket (Gates): Gates is a well-known and respected brand in the automotive industry, particularly for belts and hoses. Their products are engineered to meet or exceed OEM specifications and are a reliable alternative to OEM or OEM-supplier parts.
Pro Tip: Since the breather hose is a critical part for preventing vacuum leaks, sticking with a proven brand like CRP/Rein or Gates is highly recommended over lesser-known, budget options. The small savings are not worth the risk of poor fitment or premature failure.
Cost of Replacing the Breather Hose
The cost can vary depending on your Z4's specific engine and whether you do the work yourself or go to a shop. The parts themselves are affordable.
| Part/Service | Estimated Cost |
|---|---|
| New Aftermarket Breather Hose | $53.24 - $84.05 |
| New OEM Breather Hose | $44.00 - $70.00 |
| Shop Labor | $95 - $150 |
Frequently Asked Questions
Are there any recalls for the Z4 breather hose?
Yes, but it's for a related part. BMW issued a recall for the PCV valve heater on certain models, including the 2009-2011 Z4 with the N52 engine. This heater is designed to prevent the PCV system from freezing in cold climates. A short circuit could increase fire risk. This recall does not cover the hose itself, but it highlights the importance of the PCV system. No recalls were found for the hose itself on the 2009-2016 Z4.
How difficult is it to replace the breather hose?
The difficulty depends on your Z4's engine. On some engines, like the N54, the hose is relatively accessible at the back of the engine. 🎬 See how to replace the vent hose on N54 engines. On others, like the N52, it can be more challenging and may require removing the intake manifold for proper access. The plastic connectors can be brittle and difficult to release without breaking, so patience and the right tools are key.
What happens if I don't replace a cracked breather hose?
Ignoring a cracked breather hose will lead to persistent problems. The vacuum leak will cause a rough idle, poor engine performance, and decreased fuel economy. Over time, the incorrect crankcase pressure can cause other oil seals and gaskets to fail, leading to more widespread and expensive oil leaks.
Should I replace any other parts at the same time?
Yes, it's often a good idea. Since the breather hose is part of the larger PCV system, it's wise to inspect the other components. If your car has higher mileage, consider replacing the entire PCV valve (or oil separator) assembly along with all connected hoses. This ensures the whole system is refreshed and can save you from having to do a similar repair in the near future.
Helpful Videos
Technical Specifications
OEM Part Numbers: 11157559528 11157553949
The hose is designed for the specific engine in your Z4 (N20, N52, or N54). It is made from molded plastic and rubber to resist oil vapor and high engine temperatures, with quick-connect fittings on both ends.
We Have This Part in Stock
The information in this article is provided for general reference and educational purposes only. Vehicle specifications, procedures, and part compatibility can vary by production date, trim level, and region. Always consult your vehicle's factory service manual and verify part numbers before purchasing or performing repairs. Safety-critical components such as airbags, seat belts, and braking systems should be installed by a qualified professional.
- BMW Z4: