2003 GMC W4500 Forward Service and Repair Manual
This factory service and repair manual for the 2003 GMC W4500 Forward has three engines on its list, and it treats them as equals. Two are overhead-valve, naturally aspirated gasoline V8s — a 6.0L of 364 cubic inches and a 5.7L of 350 — and the third is a turbocharged 4.8L inline-four diesel of 290 cubic inches. The body comes as a low crew cab or a low-tilt straight truck, both under the W4S042 code, and the manual gives each engine its own procedures, specifications, torque values, wiring diagrams and diagnostics.
Engines covered
- 6.0L V8 (364 cu in) — OHV, naturally aspirated, gasoline
- 5.7L V8 (350 cu in) — OHV, naturally aspirated, gasoline
- 4.8L inline-four (290 cu in) — turbocharged, diesel
Body styles covered
- Straight truck, low crew cab
- Straight truck, low tilt
Trims covered
- W4S042
Known issues on the 2003 W4500 Forward. A single recall stands on the federal record for the 2003 W4500 Forward. It applies to trucks whose fuel switching manifold solenoids were not built to resist water and salt intrusion; a failed solenoid sends fuel where it should not go and can push it back out of the filler neck, and spilled diesel near an ignition source can ignite. One owner complaint is also logged, on the service brakes. Fuel storage and switching hardware and the full brake system are both covered here, with component procedures, specifications, torque values and diagnostics.
