2003 Ford F-350 Problems: 10 Known Issues

On the 1999-2003 Ford F-350 7.3L Power Stroke V8 diesel, the 1999-2003 F-350 with the 7.3L Power Stroke uses a camshaft position sensor at the front of the engine to time injection. The original black-bodied sensor fails intermittently, most often when it is damp or heat-soaked, cutting injection and stalling the engine without warning. Because these are hydro-boost brake and hydraulic-assist steering trucks, a stall at speed means a hard pedal and heavy steering - the reason NHTSA treated it as a safety defect. Owners describe stalling in rain, stumbling at low rpm, and no-start conditions that clear after the engine cools. Ford recalled roughly 1.17 million 1997-2003 vehicles with the 7.3L, including F-350, F-450 and F-550 Super Duty, and replaced the black sensor with a revised gray unit. The recall does not cover 1994-1996 7.3L trucks, which use the same sensor design.

On the 2003-2007 Ford F-350 6.0L Power Stroke V8 diesel, the 2003-2007 6.0L Power Stroke in the F-350 uses torque-to-yield head bolts in a high-cylinder-pressure engine with relatively few fasteners per cylinder. Under repeated heat cycles, and especially with the elevated cylinder pressures that come from towing at weight or from any power tuning, the TTY bolts stretch and lose clamp load. The head lifts momentarily, the gasket fire ring loses its seal, and combustion gas is pushed into the cooling system. This is the failure that gave the 6.0L its reputation. It is frequently downstream of the plugged oil cooler / EGR cooler problem, because the resulting overheating is what finally pushes the bolts past yield. F-350 dually and chassis-cab trucks working near GVWR see it earlier than lightly used trucks.

On the 2003-2007 Ford F-350 6.0L Power Stroke V8 diesel, the Garrett GT3782VA variable geometry turbocharger on the 2003-2007 6.0L Power Stroke controls boost by pivoting a set of vanes in the turbine housing, all tied to a single unison ring. Because the 6.0L routes heavy EGR flow and crankcase oil mist through the exhaust side, soot, ash and oil residue bake onto the vanes and unison ring; trucks that idle a lot or spend their life at light load never get hot enough to burn the deposits off, and rust adds to the binding. The vanes eventually stick partly open or partly closed. Stuck-open produces severe turbo lag and no low-end boost; stuck-closed produces overboost and a hard limp-in. This is distinct from later 6.7L turbo bearing failure - the 6.0L problem is mechanical fouling of the vane mechanism, not bearing wear.

On the 1999-2003 Ford F-350 7.3L Power Stroke V8 diesel, the 4R100 four-speed automatic fitted to 1999-2003 F-350s behind the 7.3L Power Stroke is the weak link in an otherwise durable driveline, and F-350 duty cycles - fifth-wheel and gooseneck towing near a 20,000 lb-plus combined weight - expose it. Two failure patterns dominate owner reports. First, on early 2001 units (roughly the first six months of production) Ford used a mechanical diode one-way clutch on the direct drum in place of the roller sprag; when the diode seizes the truck can lurch and skid the rear wheels on the shift into third, and Ford went back to a roller sprag. Second, the torque converter and the undersized factory cooler let fluid temperatures climb during towing, cooking the clutch packs and sending debris through the valve body and pump. A Ford TSB (02-21-1) also documents the torque converter external access dust plug falling out under severe-duty use, allowing fluid loss.

On the 2003-2007 Ford F-350 6.0L Power Stroke V8 diesel, on the 2003-2007 6.0L Power Stroke used in the F-350 Super Duty, the engine oil cooler is a stacked-plate unit with very small coolant passages that sits in the valley of the block. Casting sand left from block manufacture plus silicate dropout from degraded Ford Gold coolant progressively plug those passages. Once the oil cooler is restricted, coolant flow to the EGR cooler (which is fed downstream of the oil cooler) collapses, the EGR cooler boils its coolant locally and its core splits, dumping coolant into the intake. Industry write-ups and shop teardowns attribute roughly 90 percent of 6.0L EGR cooler failures to a plugged oil cooler upstream, which is why replacing only the EGR cooler produces repeat failures. On F-350s used for heavy fifth-wheel and gooseneck work the sustained high coolant temperatures accelerate the deposit process.

On the 2003-2007 Ford F-350 6.0L Power Stroke V8 diesel, the 6.0L Power Stroke's Fuel Injection Control Module sits on top of the driver-side valve cover and must deliver a 48-volt pulse to fire each HEUI injector. The module is heat-soaked in that location and its internal power supply degrades over time; it is also killed outright by weak batteries or a failing charging system, because the boost circuit is damaged when supply voltage sags during cranking. As FICM main power output drops below roughly 46 volts, the injector solenoids begin to open late, producing hard starting, rough cold running and white smoke. A dying FICM can subsequently damage injectors. F-350s with two batteries that are not replaced as a matched pair are the classic case.

On the 1999-2007 Ford F-350, the exhaust manifold bolts on the 6.0L and 7.3L Power Stroke diesel engines break due to thermal cycling, causing exhaust leaks with a ticking noise especially on cold starts. Broken bolts are very difficult to extract.

On the 1999-2016 Ford F-350, f-350 dually trucks run a full-floating rear axle (a Dana 80 on most, a Sterling 10.5 on some gas duallies) whose hubs carry adjustable tapered inner and outer bearings with a seal riding on the innermost part of the spindle. Unlike a sealed unit bearing, this design is a maintenance item, and the loads a DRW F-350 carries - a pin weight applied well behind the cab by a gooseneck or fifth wheel, plus the extra outboard tire - make bearing preload and lubrication critical. Owners across ford-trucks.com and thedieselstop.com report the seal weeping gear oil onto the brakes, followed by a growl that changes with load, and eventually a spun or destroyed bearing. Gear oil reaching the rear brake friction is the safety consequence, on a truck that is already brake-limited when loaded.

On the 1999-2016 Ford F-350, the 1999-2016 Super Duty cab has a double-wall rocker and cab-corner structure that traps water and road debris and rots from the inside out. On the F-350 the pattern is worse than on lighter trucks for two structural reasons: dual rear wheels throw far more salt spray and grit up onto the rear arches and cab corners than a single-rear-wheel truck, and F-350s spend disproportionate time in plow, farm and construction service where the truck is wet and salted constantly. Failure shows first as bubbling paint at the bottom of the cab corner behind the door, then perforation at the rocker seam and the rear wheel arch on the bed. Because the inner rocker is part of the cab structure, extensive rot is a structural and inspection problem, not just cosmetic.

On the 2003-2007 Ford F-350 6.0L Power Stroke V8 diesel, the 6.0L Power Stroke uses hydraulically actuated, electronically controlled unit injectors (HEUI) that are fired by high-pressure engine oil. Oxidized oil leaves a varnish film on the injector spool valve, and when the engine is cold that film creates static friction (stiction) that keeps the spool from moving on command. The result is a dead or lazy cylinder for the first minutes after a cold start, clearing as oil warms. Owners report a rough, shaking cold start that smooths out after several miles and then progressively worsens over months until the injector fails outright. Extended oil-change intervals, low-quality oil and short-trip use all accelerate it. This is an oil-side failure mode of the HEUI system and does not apply to the 6.4L or 6.7L, which use common rail.