The 2003 F-350 with the 7.3L Power Stroke is one of the most durable diesel platforms Ford ever built, but it's now 20+ years old and high-mileage examples show wear in injectors, fuel systems, and transmissions. Engine internals rarely fail unless severely neglected or abused.
Injector Failure and Stiction
Common · medium severityTypical onset: 180,000-250,000 mi
Symptoms: Hard starting, especially cold, Rough idle with white smoke, Loss of power under load, Increased fuel consumption
Fix: 7.3L injectors stick or fail electrically. Requires removing valve covers, injector replacement (often all 8 for consistency), new under-valve-cover harnesses, and injector sleeves if leaking. 10-14 hours labor depending on cab configuration.
Estimated cost: $2,800-4,500
High-Pressure Oil Pump (HPOP) and Reservoir Leaks
Occasional · high severityTypical onset: 200,000-300,000 mi
Symptoms: Extended cranking before start, Loss of power, won't rev past 2000 RPM, Oil in valley under intake, ICP sensor reading low
Fix: HEUI injection system uses high-pressure oil to fire injectors. Pump, reservoir O-rings, and lines fail. Requires intake manifold removal, HPOP replacement or rebuild, new O-rings throughout. 8-12 hours labor.
Estimated cost: $1,800-3,200
Transmission (4R100/5R110) Oil Cooler Failure
Common · high severityTypical onset: 120,000-180,000 mi
Symptoms: Transmission fluid in coolant (strawberry milkshake), Coolant in transmission, Transmission slipping or delayed engagement, Overheating
Fix: Internal radiator trans cooler ruptures, mixing fluids. Requires radiator replacement, transmission flush (sometimes full rebuild if coolant damage occurred), new cooler lines. If caught early: 4-6 hours. If trans damaged: add 12-18 hours for rebuild.
Estimated cost: $800-1,200 (cooler only), $3,500-5,500 (if trans rebuild needed)
Turbo Exhaust Pedestal Leak
Occasional · medium severityTypical onset: 150,000-250,000 mi
Symptoms: Exhaust leak sound at turbo, Loss of boost pressure, Black soot around turbo base, Check engine light with low boost codes
Fix: Exhaust manifold-to-turbo pedestal develops cracks or warps. Requires turbo removal, pedestal replacement or machining, new gaskets and bolts. 6-8 hours labor.
Estimated cost: $1,200-2,000
Glow Plug Relay and Module Failure
Common · low severitySymptoms: Hard starting in cold weather, Extended glow plug wait time, No glow plug indicator on dash, Relay clicking continuously
Fix: Relay under hood or glow plug control module fails. Simple replacement, 0.5-1 hour. However, broken glow plugs can snap off in cylinder head (common on neglected trucks), requiring head removal. Always check glow plug resistance before replacement.
Estimated cost: $150-350 (relay/module), $2,500-4,000 (if glow plug extraction required)
CPS (Camshaft Position Sensor) Failure
Occasional · high severitySymptoms: Sudden stalling while driving, No-start, cranks but won't fire, Intermittent dying at idle, No check engine light (fails instantly)
Fix: Sensor located behind front cover fails suddenly, stranding vehicle. Replacement requires draining coolant, removing front cover, sensor swap, reassembly. 3-4 hours labor. Smart owners carry a spare.
Estimated cost: $400-700
Ball Joints and Unit Bearings
Common · medium severityTypical onset: 100,000-150,000 mi
Symptoms: Clunking over bumps, Steering wander or play, Grinding noise from wheels, Uneven tire wear
Fix: Dana 60 front end ball joints wear, especially on trucks used for towing or off-road. Unit bearings also fail. Ball joint replacement: 4-6 hours both sides. Hub bearings: 2-3 hours each.
Estimated cost: $800-1,400 (ball joints), $400-700 per hub
Buy one if under 200k miles with maintenance records—among the most reliable diesel trucks ever made, but budget $3-5k for deferred maintenance on high-mileage examples.
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.