The 2016 Porsche 718 Cayman GT4 actually uses the 981-generation 3.8L flat-six (not the 718's turbo-four), making it a last-hurrah naturally-aspirated gem. These engines are generally robust, but bore scoring and IMS bearing concerns from earlier generations are replaced by connecting rod bearing wear and occasional cylinder liner issues under high-RPM track use.
Connecting Rod Bearing Wear (Track/Spirited Use)
Occasional · high severityTypical onset: 30,000-60,000 mi or sooner with heavy track use
Symptoms: Metallic knocking on cold start that disappears when warm, Oil pressure fluctuations, Metal debris in oil filter during analysis, Eventual catastrophic engine failure if ignored
Fix: Engine-out job requiring crankshaft inspection, rod bearing replacement, and often full bottom-end refresh if metal contamination has occurred. Budget 30-40 hours labor plus bearings, machine work, and assembly components. Many owners proactively replace bearings every 30k miles if tracking frequently.
Estimated cost: $8,000-15,000
Cylinder Bore Scoring / Liner Scuffing
Rare · high severityTypical onset: 40,000-80,000 mi
Symptoms: Excessive oil consumption (more than 1 qt per 1,000 mi), Blue smoke on startup or deceleration, Loss of compression in one or more cylinders, Rough idle and misfires
Fix: Requires complete engine disassembly, cylinder boring, liner replacement or nikasil re-coating, and typically new pistons and rings. 50-60 hours labor. Some cases warrant full short-block replacement which is faster but costlier in parts.
Estimated cost: $15,000-25,000
Transmission Oil Cooler Line Leaks
Common · medium severityTypical onset: 50,000-90,000 mi
Symptoms: Transmission fluid spots under car, Low fluid warning light on dash, Burnt transmission fluid smell, Occasional slipping or harsh shifts when fluid gets low
Fix: Cooler lines crack at fittings or develop pinhole leaks from road debris. Replacement involves dropping undertray and sometimes exhaust components for access. 3-5 hours labor plus lines and fresh fluid/filter service while it's apart.
Estimated cost: $800-1,500
Transmission Mount Failure
Occasional · medium severityTypical onset: 60,000-100,000 mi
Symptoms: Clunking when shifting or launching, Excessive driveline vibration especially under load, Visible tearing or separation of rubber mount, Shifter feels vague or misaligned
Fix: The rear transmission mount absorbs tremendous stress in a mid-engine platform, especially with aggressive driving. Replacement requires supporting transmission, removing mounting bolts, and installing new mount. 2-3 hours labor. Often done with clutch jobs to save duplicate labor.
Estimated cost: $600-1,000
Fuel Filter Clogging (Track Use)
Occasional · medium severitySymptoms: Lean fuel trims and check engine light, Power loss at high RPM, Stumbling or hesitation under full throttle, Hard starting when fuel pump primes
Fix: Track use with low fuel levels sloshes sediment and debris into the filter. The in-tank filter requires fuel tank drop and pump module removal. 4-6 hours labor. Porsche recommends replacement every 4 years regardless, but track cars need it more frequently.
Estimated cost: $700-1,200
Head Gasket Seepage (Not Catastrophic)
Rare · low severityTypical onset: 80,000-120,000 mi
Symptoms: Minor oil seepage at cylinder head-to-block junction, Slight coolant smell without visible leaks, Slow coolant loss over thousands of miles, No overheating or mixing of fluids
Fix: These motors can develop minor head gasket weeps that don't require immediate attention. If addressing, engine-out is typical for complete access to both banks. 40-50 hours labor including gaskets, ARP studs upgrade recommended, and all ancillary seals while apart.
Estimated cost: $10,000-16,000
Absolutely buy one—the last naturally-aspirated GT4 is a future classic, but only if you can handle $3k-5k annual maintenance and understand rod bearings are a wear item with track use.
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.