The 2011 Cayman S (987.2 generation) with the 3.4L MA1.21 flat-six is generally reliable, but suffers from the infamous intermediate shaft (IMS) bearing issue in earlier engines and, more critically for this year, potential bore scoring and cylinder liner wear that can lead to catastrophic engine failure requiring complete rebuilds.
Cylinder Bore Scoring / Localized Cylinder Wall Wear
Occasional · high severityTypical onset: 60,000-120,000 mi
Symptoms: Excessive oil consumption (more than 1 qt per 1,000 mi), Cold-start smoke from exhaust (blue/white), Loss of compression in one or more cylinders, Metallic noise or ticking from engine, especially on cold starts
Fix: Complete engine rebuild or replacement required. If caught early, single-cylinder sleeving or new piston/liner sets may suffice (25-35 hours), but most cases need full short block replacement or complete rebuild with bore treatment (45-60 hours). This is the biggest financial risk on these cars.
Estimated cost: $12,000-25,000
Rear Main Seal (RMS) Leak
Common · medium severityTypical onset: 70,000-110,000 mi
Symptoms: Oil pooling under rear of engine/transmission bell housing, Oil weeping visible around flywheel area during inspection, Gradual oil level drops between changes
Fix: Requires transmission and flywheel removal to access seal. Labor-intensive but straightforward. Plan on 12-16 hours labor, includes clutch inspection while you're in there—smart to replace clutch at same time if over 60k mi.
Estimated cost: $2,200-3,800
Coolant Expansion Tank Cracking
Common · medium severityTypical onset: 80,000-130,000 mi
Symptoms: Coolant smell in cabin or engine bay, Visible coolant seepage or white residue on tank sides, Low coolant warnings on dash, Overheating if leak becomes severe
Fix: Plastic expansion tank develops stress cracks at mounting tabs or seams. Simple replacement, 1.5-2.5 hours labor. Often inspect radiator end tanks at same time—they crack too.
Estimated cost: $400-700
Transmission Oil Cooler Line Leaks
Occasional · medium severityTypical onset: 90,000-140,000 mi
Symptoms: Transmission fluid spots on ground (reddish/brown), Fluid visible along cooler lines or fittings at radiator, Transmission running hotter than normal, Low fluid level on dipstick (manual trans) or faults (PDK)
Fix: Rubber lines harden and crack or fitting O-rings fail. Lines themselves are not expensive but access requires removing undertray and sometimes front fascia components. 3-5 hours labor for lines and fluid refill.
Estimated cost: $600-1,200
Engine/Transmission Mounts Deterioration
Common · low severityTypical onset: 70,000-100,000 mi
Symptoms: Clunking on acceleration or deceleration, Excessive driveline vibration at idle, Shifter vibration (manual trans), Visible tearing or fluid weeping from mounts
Fix: Hydraulic mounts wear out and lose damping fluid. Replacing all engine and transmission mounts requires supporting drivetrain from below. 6-9 hours labor depending on how many mounts are replaced. OEM mounts strongly recommended.
Estimated cost: $1,800-3,000
Air-Oil Separator (AOS) Failure
Occasional · medium severityTypical onset: 80,000-120,000 mi
Symptoms: White smoke from exhaust on deceleration, Oil in intake plenum or throttle body, Check engine light with mixture codes (P0171, P0174), Rough idle or misfires
Fix: Internal diaphragm ruptures, allowing crankcase pressure to push oil into intake. Replacement requires removing intake manifold. 4-6 hours labor. Use OEM part only—aftermarket units fail prematurely.
Estimated cost: $1,200-1,800
Buy one with documented low oil consumption and clean borescope results, otherwise you're gambling on a $15k-20k engine rebuild—great driver's car if you get a good one, financial nightmare if you don't.
AI-assisted summary drawn from NHTSA recall data, our labor-times database, and platform knowledge. Not a substitute for a pre-purchase inspection on a specific vehicle.