The 2017 Q70 is Infiniti's flagship sedan built on the aging Y51 platform. While generally reliable, the 3.7L V6 has documented catastrophic engine failures, and transmission cooling issues affect multiple drivetrain configurations.
Catastrophic 3.7L VQ37VHR Engine Failure
Occasional · high severityTypical onset: 80,000-140,000 mi
Symptoms: Metal flakes in oil during changes, Sudden loss of oil pressure with warning light, Knocking or ticking that progresses to complete seizure, Coolant mixing with oil (milky dipstick)
Fix: Complete engine replacement or rebuild required. Typical bearing failure starts at main or rod bearings, often spreading to require full short block. 18-24 labor hours for complete R&R with used engine, 30-40 hours for full rebuild with machine work.
Estimated cost: $6,500-12,000
Transmission Oil Cooler Failure and Cross-Contamination
Common · high severityTypical onset: 70,000-110,000 mi
Symptoms: Transmission fluid in coolant (pink residue in expansion tank), Coolant in transmission (milky ATF on dipstick), Harsh shifting or slipping after cooler breach, Overheating transmission temperature warnings
Fix: Internal radiator transmission cooler corrodes and fails, allowing fluid mixing. Requires radiator replacement, transmission flush (multiple fills), possible torque converter replacement if contaminated. Add 8 hours if transmission damage requires rebuild. Critical to catch early before destroying transmission. 6-8 hours for cooler/radiator only.
Estimated cost: $1,800-3,500
Transmission Mount Failure (All Engines)
Common · medium severityTypical onset: 60,000-90,000 mi
Symptoms: Clunking when shifting from Park to Drive or Reverse, Vibration at idle in gear that disappears in Park/Neutral, Excessive drivetrain movement visible from engine bay during acceleration, Bouncing or shuddering during throttle tip-in
Fix: Hydraulic transmission mount deteriorates, allowing excessive drivetrain movement. Replacement requires supporting transmission and removing mount bolts. 2-3 hours labor. Often done with engine mounts if those are also worn.
Estimated cost: $450-750
Driveshaft Center Support Bearing Failure (RWD/AWD)
Occasional · medium severityTypical onset: 75,000-120,000 mi
Symptoms: Droning or humming at highway speeds (50-70 mph), Vibration through floor that changes with speed, Clunking during acceleration/deceleration transitions, Grinding noise from undercarriage center section
Fix: Center support bearing wears out, causing vibration and potential driveshaft imbalance. Related to NHTSA recall on some units. Requires driveshaft removal and bearing/carrier replacement. 3-4 hours labor. Some units need complete driveshaft assembly if bearing is not serviceable separately.
Estimated cost: $650-1,400
Hybrid Battery Pack Deterioration (3.5L Hybrid Only)
Occasional · high severityTypical onset: 100,000-150,000 mi
Symptoms: Reduced fuel economy (MPG drops significantly), Hybrid system warning lights and reduced power mode, Engine runs constantly even at low speeds, Battery charge gauge shows limited capacity or won't charge fully
Fix: Lithium-ion battery pack degrades over time. Infiniti warranty covers 8yr/100k mi, but failures after warranty are expensive. Replacement requires 8-10 hours for pack R&R, programming, and testing. Used packs available but risky. Remanufactured packs preferred.
Estimated cost: $5,000-8,500
Fuel System Contamination from In-Tank Filter Breakdown
Rare · medium severityTypical onset: 90,000-130,000 mi
Symptoms: Hard starting after sitting overnight, Intermittent rough idle and misfires, Check engine light with fuel trim codes (P0171, P0174), Loss of power at highway speeds
Fix: In-tank fuel filter/strainer deteriorates and sends debris through fuel system. Requires fuel tank drop, pump/filter replacement, injector cleaning or replacement if contaminated. 5-7 hours for tank drop and pump service, add 3-4 hours if injectors need service.
Estimated cost: $900-2,200
Skip the 3.7L V6 due to catastrophic engine failure risk; Hybrid or 5.6L V8 are better bets if you can verify transmission cooler has been addressed and maintain it religiously—otherwise, too much expensive risk for a luxury sedan.
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.