The infamous E90 Pcv Valve Whine is a common issue for BMW owners, often indicating a failing PCV membrane. This article details the problem, provides a solution using readily available parts, and offers advice on preventing future occurrences. This whine can be a precursor to more serious engine problems, so addressing it promptly is crucial.
Understanding the E90 PCV System and Whine
The Positive Crankcase Ventilation (PCV) system plays a vital role in reducing harmful emissions and maintaining engine health. A key component of this system is the PCV valve, which regulates the flow of gases from the crankcase back into the intake manifold. Inside the valve cover, a membrane within the PCV valve regulates pressure. When this membrane tears or deteriorates, it creates a vacuum leak, often manifesting as a noticeable whining sound coming from the engine bay. This is commonly referred to as the “E90 PCV valve whine.” Ignoring this whine can lead to rough idling, poor fuel economy, and even engine damage.
Identifying the Culprit: The PCV Membrane
The primary cause of the E90 PCV valve whine is a torn or damaged PCV membrane. Unlike other BMW models, the N53 engine in the E90 requires a specific type of membrane and cap. Many aftermarket “N53 compatible” kits include a plastic cap with an integrated membrane. However, these are often incompatible. The N53 requires a full-width membrane and a flat aluminum cap. Using the incorrect part will likely result in a persistent whine and potential air leaks.
The Solution: Replacing the PCV Membrane and Cap
The solution to the E90 PCV valve whine is to replace the faulty membrane with a compatible one and, ideally, upgrade to an aluminum cap. While replacing just the membrane might seem sufficient, the aluminum cap offers several advantages:
- Reusability: If the membrane fails again, you can simply replace the membrane without needing a new cap.
- Heat Dissipation: Aluminum dissipates heat more effectively, potentially extending the life of the membrane.
- Durability: The aluminum cap is more robust than the original plastic cap.
Sourcing the correct parts can be tricky. While readily available online from vendors specializing in BMW parts, ensure you’re purchasing a standalone membrane and a flat aluminum cap specifically designed for the N53 engine.
Performing the Repair: A Step-by-Step Guide
While a professional mechanic can perform this repair, it’s relatively straightforward for DIY enthusiasts. Here’s a simplified overview:
- Remove the Engine Cover: Access the valve cover by removing the engine cover.
- Remove the Old Cap: Gently heat the old cap with a hairdryer to soften the adhesive. Carefully pry it off using a screwdriver. Be mindful of the retaining clips, as they can be brittle.
- Clean the Valve Cover: Clean the mating surface on the valve cover to ensure a proper seal for the new cap.
- Install the New Membrane and Cap: Insert the new membrane into the aluminum cap and press it firmly onto the valve cover. Using a sealant can help ensure an airtight seal, especially if the retaining clips are broken.
Preventing Future E90 PCV Valve Whine
Regular maintenance and using quality oil can help prolong the life of the PCV membrane. Inspecting the membrane during routine oil changes can help identify potential issues before they become symptomatic.
Conclusion
The E90 PCV valve whine is a common problem with a relatively simple solution. By understanding the cause, identifying the correct parts, and following the proper repair procedure, you can eliminate the whine and restore your BMW’s performance. Addressing this issue promptly will prevent further engine problems and ensure a smoother, more enjoyable driving experience. Remember to source the correct parts specifically designed for the N53 engine to avoid recurring issues.
