Porsche 718 Cayman GT4 982

The Porsche Active Drivetrain Mount (PADM) uses oil-filled mounts with magnetic particles that stiffen when current is applied. These are known to fail across the 718 range, with the GT4 being no exception. Symptoms include a 'PADM deactivated' dashboard message, increased vibrations through the steering wheel, and loss of Sport/Sport Plus mode responsiveness. The mount itself costs around €900-1,200, with labor running €800-1,500 depending on whether one or both sides fail. Both gearbox mounts failing within 12 months of each other is commonly reported. If a geometry reset is needed afterwards, add approximately €400-500. Failures can appear from as early as 15,000 km and there is no clear pattern linked to mileage or driving style. Porsche has covered this under warranty for many owners, but out-of-warranty repair is expensive.

The coolant expansion tank on the 4.0 engine is prone to cracking from thermal stress. Early failures have been documented from as low as 8,000 km. Symptoms include a coolant warning light, a sweet coolant smell from the rear, and a puddle near the rear driver-side wheel. The part itself is relatively inexpensive, but the intake manifold must be removed to access it on the GT4, adding labor time. Some owners have traced failures to overtightened caps during dealer servicing. The repair typically costs €800-1,800 depending on the shop.

The rear main seal on the 4.0 flat-six can develop a slow oil leak, typically becoming noticeable after 60,000-80,000 km. If oil reaches the clutch friction plate, it causes chatter, slippage under load, and eventually requires a full clutch replacement alongside the seal. The repair is expensive because the entire gearbox must be removed. If only the seal needs replacing, expect €2,000-3,000. If the clutch is contaminated and also needs replacement, the total can reach €4,500-5,500. This is not unique to the GT4 but affects the 4.0 engine family broadly.

Porsche recalled 190 vehicles built between 18 September 2020 and 4 March 2021, affecting the 2021 GT4, GTS 4.0, Spyder, and Boxster GTS 4.0 with the 4.0 flat-six. The connecting rods were not manufactured to specification and could crack, leading to engine damage, stalling, or oil leaks. Porsche replaced connecting rods or entire engines free of charge (recall AMA4). When buying a used GT4, especially a 2020-2021 build, verifying this recall is completed is essential. The recall itself costs nothing, but buying a car where it was missed could result in catastrophic engine failure.

The water pump on the 4.0 flat-six can fail prematurely, typically between 50,000 and 80,000 km. Symptoms include a whining noise from the pump area, visible coolant leaks, and erratic temperature gauge behavior. The intake manifold needs to be removed for access, adding to labor costs. Parts run approximately €400-600, with total repair costs of €1,000-2,500 depending on the shop. Some owners replace the water pump preventively when doing other work that requires manifold removal.

Like all direct-injection engines without supplementary port injection, the 4.0 flat-six accumulates carbon deposits on the intake valve stems over time. This gradually reduces airflow and can cause rough idling, reduced power, and misfires, typically becoming noticeable after 60,000-80,000 km. Walnut blasting is the standard remedy, costing €500-1,200 depending on the shop. The intake manifold removal required on the GT4 adds to labor. This is preventive maintenance rather than a sudden failure, and many owners schedule it every 50,000-60,000 km.

The six ignition coils on the 4.0 engine can fail prematurely when the car sees regular track duty. Sustained high temperatures degrade the coil insulation. Aftermarket exhaust headers without proper heat shielding significantly accelerate this failure. Individual coil replacement costs around €50-80 per coil, but the intake manifold must be removed for access, making the labor cost disproportionate. A full set of six coils plus labor runs €400-1,500. For street-only cars, this is rarely an issue within normal service intervals.

A well-documented issue across the 718 range: the factory Oetiker ear clamps on the inner CV boots can be loose from the factory. Under track use or spirited driving, high temperatures and lateral forces liquify the lithium grease, which then gets flung past the loose clamp. This appears as grease spray around the rear axle area. If caught early, re-clamping costs under €100. If the boot tears or the CV joint runs dry, replacement costs €300-600 per side. Regular visual inspection after spirited drives is advisable.