Porsche Cayman AOS Replacement Parts: What You Need to Know

The Air Oil Separator (AOS) is a critical component in your Porsche Cayman’s engine. Over time, the AOS can fail, causing oil leaks, smoke, and performance issues. When that happens, you need to replace it with the right parts. This guide covers everything you need to know about Porsche Cayman AOS replacement parts, from symptoms and options to cost and installation. Whether you’re a DIYer or planning to visit a shop, this information helps you make an informed decision.

Understanding the AOS in Your Porsche Cayman

What the AOS Does

The AOS separates oil from the crankcase ventilation gases before they re-enter the intake. In the Cayman, the AOS is a common failure part, especially on higher-mileage cars. A faulty AOS leads to excessive oil consumption, blue smoke from the exhaust (especially on deceleration), rough idle, and even oil in the intake tract. Catching it early prevents more expensive damage.

Signs Your AOS Needs Replacement

• Blue smoke from exhaust during deceleration or after idling
• Oil consumption increasing noticeably (more than 1 quart per 1,000 miles)
• Rough idle or stalling, especially when the engine is warm
• Oil leaks around the AOS area on the engine
• Check engine light (often related to lean or rich codes)

If you notice any of these, inspect the AOS. It’s located on the driver’s side of the engine near the intake manifold. A visual check might reveal oil residue or cracks.

OEM vs Aftermarket AOS Replacement Parts

OEM Porsche AOS

OEM (Original Equipment Manufacturer) parts come from Porsche and are identical to the original. The OEM AOS part number for most Cayman models (2006–2012, 987.1 and 987.2) is 997-107-022-00 or similar (check your specific year). OEM ensures perfect fit and reliability, but it comes at a higher price—typically $150 to $250 for the part alone.

Aftermarket AOS Kits

Several reputable aftermarket brands produce AOS replacements for the Porsche Cayman, such as URO, Meyle, and Febi Bilstein. These often cost $60 to $120. Some aftermarket AOS units are made with updated materials to address the original design weaknesses. For example, URO’s AOS includes a reinforced housing and improved check valve. While aftermarket parts can save money, quality varies. Stick with known brands to avoid premature failure.

A common upgrade is the “AOS delete” or “catch can” system, but that changes the engine’s ventilation design. For a direct replacement, use a new AOS unit.

Cost of Porsche Cayman AOS Replacement

• Part cost: OEM $150–$250, aftermarket $60–$120
• Labor (if installed by shop): $200–$400 (2–3 hours at $100–$150/hr)
• Total DIY cost: Just the part plus a few minor items (gaskets, clamps)
• Shop total: $350–$650

Note: Some shops charge extra if the AOS is difficult to access. The Cayman’s AOS is accessible but requires removing the intake manifold on some models. Factor in a new intake gasket if you remove the manifold.

Installation Guidance

Tools Needed

• Socket set (metric, 10mm, 13mm, etc.)
• Torx bits (T30, T40)
• Flathead screwdriver
• New intake manifold gasket (if applicable)
• New hose clamps (optional but recommended)
• Clean rags and degreaser

Steps Overview

1. Disconnect the battery (negative terminal).
2. Remove the engine cover and intake duct.
3. Carefully disconnect the electrical connectors on the intake manifold.
4. Unbolt the intake manifold (if needed). On some Cayman variants, you can reach the AOS without fully removing it—just pivot it aside.
5. Label the vacuum lines and hoses connected to the AOS.
6. Remove the old AOS. It’s held by two bolts and a hose clamp.
7. Clean the mounting surface and inspect for oil residue.
8. Install the new AOS with new O-rings (if supplied) and torque bolts to spec.
9. Reconnect hoses, intake, and electrical connectors.
10. Start the engine and check for leaks and proper idle.

Note: If you’re not comfortable with engine work, have a professional do it. Improper installation can cause vacuum leaks or engine damage.

Final Recommendation

For most Porsche Cayman owners, the best value is a quality aftermarket AOS from a reputable brand like URO or Meyle. They offer a good balance of price and durability. If you want absolute peace of mind and plan to keep the car long-term, OEM is the safe choice. Always replace the intake gasket and any worn hoses at the same time. After replacement, monitor oil consumption and smoke to confirm the fix. A properly functioning AOS restores engine performance and reliability.