Porsche Cayman 2.7 987

The AOS is a crankcase ventilation component that separates oil from blow-by gases. The internal rubber diaphragm deteriorates over time due to heat exposure, typically failing between 60,000 and 100,000 km. When it fails, oil gets drawn into the intake manifold, causing blue/white exhaust smoke on startup, rough or hunting idle, increased oil consumption, and various fault codes. The genuine Porsche replacement part costs €80-150. Labor runs 3-4 hours on the Cayman, totaling €400-900 at a specialist. If left uncorrected, a failed AOS can contribute to a lean fuel condition that accelerates cylinder wear. Porsche specialists commonly recommend treating the AOS as a maintenance item and replacing it every 6 years or 100,000 km regardless of symptoms.

Two related cooling system weak points affect the 987.1 Cayman. The water pump uses a plastic impeller that can shed blades over time, reducing coolant flow and causing localized overheating. Broken impeller fragments can block passages in the cylinder heads. Water pump failure is a well-documented issue on the M97 engine, with some owners reporting premature failures as early as 60,000-80,000 km. The plastic coolant expansion tank, located in the rear trunk area, becomes brittle after 8-10 years and develops hairline cracks that leak under pressure. Water pump replacement costs €500-800 at a specialist (upgraded metal impeller pumps are available). Expansion tank replacement costs €200-400. Both should be considered preventive items on any 987.1 still running original components.

The 987 Cayman's shift cables route from the centre console to the mid-mounted gearbox, passing through tight bends. Metal fatigue develops at these stress points, and cables can snap without warning, leaving the car immobilized in whatever gear was selected. This is a well-documented 987 issue with numerous forum reports. Porsche released updated cable brackets and revised cable part numbers to address the problem. Replacement with updated OEM cables costs approximately €500-800 for parts plus 3-4 hours labor. Aftermarket options from Numeric Racing offer lifetime-guaranteed cables for a similar price. Some owners carry a zip tie in the car to temporarily lash a broken cable. Tiptronic-equipped cars are not affected.

The rear main seal sits where the crankshaft exits the engine to meet the gearbox. The M97 engine can develop a weep from this seal, particularly on higher-mileage cars. When the seal fails significantly, oil can contaminate the clutch disc, causing slippage and requiring clutch replacement as well. The seal itself costs under €50, but the gearbox must be removed for access, making it labor-intensive (8-10 hours). Standalone RMS replacement costs €1,000-1,500 at a specialist. Most Porsche specialists recommend combining RMS work with clutch renewal, as the gearbox is already removed. A minor weep can often be monitored rather than immediately repaired. Severe leaks that contaminate the clutch push the total repair bill to €2,000-2,500.

The 987.1 engine features a plastic coolant pipe that connects the front of the engine to the primary cooling outlet hose. The rubber seals between the plastic pipe and the engine block swell and degrade over time, producing a slow coolant leak. The parts themselves are inexpensive (under €100), but access requires removing the intake manifold, turning this into a 6-8 hour labor job. Total repair cost at a specialist runs €500-900, or €900-1,200 at a Porsche dealer. Porsche released an updated vent hose for 2005-2008 models (part 98710653101) that should be installed at the same time. Many specialists recommend proactively replacing all coolant pipe seals during any major service that involves intake manifold removal.

The IMS bearing is the most discussed risk on M96/M97 Porsche engines. However, all Caymans were built from MY2006 onward and received the improved Gen III IMS bearing, which has an estimated failure rate well below 1%. No verifiable case of a Cayman with the problematic single-row bearing has been documented. This stands in sharp contrast to earlier 986 Boxsters with 8-10% failure rates. When the bearing does fail, metal debris circulates through the engine oil and causes catastrophic internal damage. A preventive IMS bearing upgrade costs €1,500-2,500 (8-10 hours labor, gearbox removal required) and is best combined with RMS and clutch work. If the bearing fails before replacement, engine rebuild costs run €8,000-10,000. While the statistical risk is very low, buyers who want complete peace of mind can opt for the preventive upgrade.

The M97 engine's ignition coils have been updated several times by Porsche, with earlier versions prone to developing cracks in their housings. Low-mileage 987.1s that have never had coils replaced often still have the original failure-prone version. Forum reports of cars with 30,000 km showing 5 of 6 cracked coils are not uncommon. Additionally, spark plug tube seals can leak oil into the plug wells, fouling plugs and destroying coil boots, which causes misfires. Replacing all 6 coils and spark plug tube seals together costs approximately €300-700 at a specialist. Using the latest-revision Porsche coils is recommended. This is a straightforward job and a sensible preventive measure on any 987.1 with original coils.

The 987 Cayman uses cable-driven window regulators with plastic pulleys and guides. These components wear and eventually break, causing the frameless window to jam, drop into the door, or fail to auto-drop when the door handle is pulled (a safety feature on frameless doors). Replacement costs €300-600 per door including parts and labor. The issue affects both driver and passenger sides and is considered a wear item on older 987s. Porsche updated the regulator design during the production run but the fundamental cable-and-pulley mechanism remains susceptible to age-related failure.