The 2017 Navigator marks the final year of the third-generation body-on-frame SUV before a complete redesign. Most still run the 5.4L Triton V8 (carryover platform from 2007-2014), though some early-build transition units may have the 3.5L EcoBoost. The Triton engines at this age are showing serious internal wear issues.
5.4L Triton V8 Cam Phaser & Timing Chain Failure
Common · high severityTypical onset: 80,000-140,000 mi
Symptoms: Cold-start rattle lasting 5-15 seconds, Check engine light with P0016/P0017 timing codes, Rough idle and loss of power, Metallic clattering under acceleration
Fix: Requires timing chain set replacement, cam phasers (both), updated tensioners, and often VCT solenoids. Engine must come partially out or cab lifted for access. 18-24 labor hours at most shops. If metal debris circulated, expect oil pump and bearing damage requiring full teardown.
Estimated cost: $3,500-6,500
Spark Plug Ejection / Cylinder Head Thread Failure
Occasional · high severityTypical onset: 70,000-120,000 mi
Symptoms: Sudden loud POP and hissing sound from engine bay, Cylinder misfire codes, Loss of power, Spark plug literally blown out of head
Fix: The 5.4L 3-valve heads have notoriously weak spark plug threads. When plugs eject, thread repair kits (HeliCoil/Time-Sert) work if caught early—3-5 hours per cylinder. Severe cases need cylinder head removal and professional thread insert or head replacement. Always use motorcraft plugs torqued to EXACT spec (27 ft-lb) and anti-seize.
Estimated cost: $800-3,200
Transmission Oil Cooler Line Corrosion & Leaks
Common · medium severityTypical onset: 60,000-100,000 mi
Symptoms: Transmission fluid dripping near radiator area, Pink fluid spots under vehicle, Low transmission fluid warnings, Burnt transmission smell if run low
Fix: Steel cooler lines rust through where they connect to radiator or run along frame in salt-belt states. Replace both feed and return lines as a pair—they'll both fail eventually. 3-4 hours labor, includes fluid flush. Ignore it and you'll cook the 6R80 transmission ($4,500+ rebuild).
Estimated cost: $600-1,100
6R80 Transmission Torque Converter Shudder
Common · medium severityTypical onset: 70,000-110,000 mi
Symptoms: Vibration at 35-45 mph during light acceleration, Feels like driving over rumble strips, Worse when transmission is cold, May improve temporarily after fluid change
Fix: Torque converter clutch material deteriorates, contaminating fluid. Temporary fix: drain/fill with Mercon LV three times over 1,000 miles (3 hours total). Permanent fix requires converter replacement and flush—transmission comes out. 10-12 hours labor.
Estimated cost: $2,200-3,800
HVAC Blower Motor Failure (Recall 17V-399)
Occasional · low severitySymptoms: No air blowing from vents on any speed, Burning smell from dash, Blower works intermittently then quits, Potential fire risk per NHTSA recall
Fix: Blower motor overheats due to debris accumulation or bearing failure. Ford recall covers inspection and replacement if failed. Outside recall: motor is behind glove box, 1.5-2 hours labor. Check cabin air filter first—clogged filters cause premature failure.
Estimated cost: $350-550
Rear Air Suspension Compressor & Line Leaks
Occasional · medium severityTypical onset: 80,000-130,000 mi
Symptoms: Rear sags overnight or after sitting, Compressor runs constantly (listen near spare tire), Suspension warning light, Hissing from rear when parked
Fix: Air springs themselves usually last, but compressor seals and plastic airline fittings crack. Compressor replacement: 2-3 hours. Air line repair kits available but finding the exact leak point takes time. Can limp with compressor fuse pulled (rides on bump stops) but handling suffers. Full system conversion to coils runs $800-1,200 in parts if you're done with air.
Estimated cost: $1,200-2,000
Brake Booster Vacuum Leak (Recall 17V-099)
Occasional · high severitySymptoms: Hard brake pedal requiring excessive force, Hissing sound when pressing brakes, Engine stalling at idle after braking, Extended stopping distances
Fix: Vacuum check valve in brake booster can fail, causing loss of power assist. Ford recall 17V-099 addresses this—dealership will replace booster assembly if affected. Outside recall window: booster replacement requires master cylinder removal, 4-5 hours labor.
Estimated cost: $900-1,400
Hard pass unless under 60,000 miles with impeccable service records—the 5.4L Triton at this age is a ticking time bomb for $4,000+ engine work, and these are the last of a 10-year-old platform with known weak points.
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.