The 2017 718 Cayman S with its 2.5L turbo flat-four is a strong performer, but early turbo four-cylinder 718s suffer from a catastrophic engine defect: cylinder scoring and bearing failure, primarily affecting 2017-2019 models. When it happens, it's not a repair—it's a full rebuild or replacement.
Cylinder Scoring and Bearing Failure (Engine Carnage)
Occasional · high severityTypical onset: 30,000-70,000 mi
Symptoms: metallic knocking or ticking from engine bay, especially cold start, sudden oil consumption increase (1+ qt per 1,000 mi), white or blue smoke on startup, loss of compression on cylinder 2 or 3 most commonly, check engine light with misfire codes
Fix: This is a total engine failure requiring either short block replacement (12-18 hours labor) or complete engine rebuild with new pistons, rings, bearings, and bore honing (25-35 hours). Porsche extended warranty coverage to 10 years/120,000 miles for affected VINs, but out-of-warranty cases are financially devastating. Many shops won't attempt in-chassis rebuild due to precision required—recommend factory short block.
Estimated cost: $18,000-28,000
Transmission Oil Cooler Line Leaks
Common · medium severityTypical onset: 40,000-80,000 mi
Symptoms: transmission fluid spots under vehicle, left side, low fluid warning on PDK-equipped cars, burnt transmission fluid smell after spirited driving, visible seepage at cooler line connections behind front bumper
Fix: PDK oil cooler lines develop leaks at crimped fittings or rubber sections crack from heat cycling. Requires bumper removal for access, replace both supply and return lines as a set (3-4 hours labor). OEM lines mandatory—aftermarket don't seal properly.
Estimated cost: $800-1,200
Transmission Mount Failure (PDK)
Common · low severityTypical onset: 50,000-90,000 mi
Symptoms: clunk when shifting from reverse to drive or vice versa, vibration through chassis at idle in gear, excessive driveline lash during throttle transitions, visible sagging or cracking of rubber mount
Fix: Rear transmission mount deteriorates from heat and vibration, especially on cars driven hard. Access is from underneath, requires transmission support (2-3 hours labor). Upgrade to aftermarket solid or polyurethane mount is common modification during replacement.
Estimated cost: $400-700
Fuel Filter Clogging (Ethanol-Related)
Occasional · medium severitySymptoms: rough idle or misfires under load, loss of power above 4,000 rpm, extended cranking before start, lean fuel trim codes (P0171/P0174), fuel pressure lower than 58 psi spec
Fix: In-tank fuel filter assembly clogs prematurely with ethanol-blend fuels, particularly E15 or higher. Requires fuel tank drop (4-5 hours labor). Replace entire fuel pump/filter module assembly—filter is not serviceable separately. Use only Top Tier gas to prevent recurrence.
Estimated cost: $1,200-1,800
Turbocharger Wastegate Rattle
Occasional · low severityTypical onset: 20,000-60,000 mi
Symptoms: rattling sound from engine bay between 1,800-2,500 rpm under light load, sound disappears under acceleration or at idle, no performance loss or codes, most noticeable in 3rd-4th gear cruise
Fix: Wastegate actuator rod develops play in bushing, causing characteristic rattle. Porsche issued updated turbochargers with revised actuators under warranty for many cases. Requires turbo removal for actuator replacement or full turbo swap (8-10 hours labor per side if both affected). Does not affect reliability but annoying.
Estimated cost: $2,500-4,000
Coolant Expansion Tank Cracking
Occasional · medium severityTypical onset: 60,000-100,000 mi
Symptoms: coolant smell in cabin or under hood, visible coolant seepage at tank seams, low coolant warning light, steam from rear engine bay after shutdown, coolant level drops without external leaks visible
Fix: Plastic expansion tank develops stress cracks at mounting tabs or seams from heat cycling. Tank is buried behind left rear wheel liner. Requires wheel removal and liner drop (2-3 hours labor). Replace tank, cap, and system flush. Inspect all coolant hoses while accessible.
Estimated cost: $600-900
Brilliant chassis and transmission, but the 2017 engine is a landmine—only buy with documented Porsche warranty coverage or provable cylinder health via borescope, otherwise budget for catastrophic failure or walk away.
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.