2017 PORSCHE CAYENNE TURBO

Typical onset: 40,000-80,000 mi

Symptoms: excessive oil consumption (1qt per 1,000 mi or more), cold-start smoke from exhaust, rattling or knocking noises on cold start, misfires and rough idle, complete loss of compression in one or more cylinders

Fix: This is the Achilles heel of the 4.8L twin-turbo. Cylinder liners develop scoring due to inadequate cooling and marginal bore coating—Porsche never fully resolved this from the 957 generation. Full engine rebuild or short block replacement required. Expect 40-60 labor hours for a complete teardown, machining/sleeving if salvageable, or short block swap. Many shops recommend going straight to a factory remanufactured engine.

Estimated cost: $18,000-30,000

Typical onset: 60,000-100,000 mi

Symptoms: transmission fluid spots under vehicle, transmission overheating warnings, burnt transmission fluid smell, delayed or harsh shifts when hot

Fix: The plastic end tanks on the transmission oil cooler crack, and the hard lines running to the radiator corrode or fracture at the crimps. Cooler replacement requires front bumper removal and some radiator support work. Lines can be replaced separately but often done together. 6-9 hours labor depending on line routing complexity.

Estimated cost: $1,800-3,200

Typical onset: 50,000-90,000 mi

Symptoms: clunking when shifting from Park to Drive or Reverse, vibration at idle in gear, excessive driveline movement felt during acceleration, visible sagging or tearing of rubber mount

Fix: The rear transmission mount absorbs huge torque loads from the twin-turbo V8 and fatigues quickly. Replacement is straightforward but requires a transmission jack and subframe support. 3-4 hours labor. OEM mounts last longer than aftermarket.

Estimated cost: $600-1,000

Typical onset: 70,000-110,000 mi

Symptoms: rough idle and hesitation under load, long cranking before start, limp mode or reduced power warnings, fuel pressure fault codes (P0087, P0088), no-start condition

Fix: The high-pressure fuel pump on the direct-injection system wears and loses pressure, often taking out the fuel filter and contaminating injectors. Pump is mounted low on the engine and requires removal of undertray and some intake components. Filter is integral to the pump assembly. 4-6 hours labor. If injectors are fouled, add another $2,000-3,000.

Estimated cost: $2,200-3,500

Typical onset: 60,000-100,000 mi

Symptoms: rattling noise at idle or light throttle (sounds like marbles), overboost or underboost fault codes, reduced power and sluggish acceleration, turbo whistle or whine changes pitch

Fix: Wastegate actuator rods and bushings wear, causing the flapper to rattle inside the turbine housing. Can sometimes be repaired with revised actuators, but often requires turbo replacement or rebuild. Turbos are buried under intake manifold and heat shields. 12-16 hours labor per side if replacing turbos.

Estimated cost: $3,500-6,000 per turbo

Typical onset: 70,000-120,000 mi

Symptoms: coolant smell in cabin or engine bay, visible coolant seepage on rear of engine, low coolant warnings, overheating in severe cases

Fix: Plastic coolant pipes routed along the back of the engine and thermostat housings crack from heat cycling. Access is terrible—often requires intake manifold removal and working blind behind the engine. 8-12 hours labor depending on which pipes are leaking.

Estimated cost: $1,500-2,800

Typical onset: 60,000-110,000 mi

Symptoms: vehicle sagging at one corner or entire side, compressor running constantly (hear it cycling), suspension warning lights and fault codes, harsh ride quality or bottoming out

Fix: Air struts leak at the bellows or piston seals, and the compressor wears out from overwork trying to maintain pressure. Struts are 3-4 hours each, compressor is 2-3 hours. Many owners convert to Bilstein coilovers to eliminate future air suspension headaches.

Estimated cost: $1,200-2,000 per strut, $1,800-2,500 for compressor