This factory service and repair manual for the 1997 GMC W3500 Forward serves a medium-duty cabover that a buyer could order as a diesel or as a gasoline truck. The diesel is a turbocharged 3.9L inline-four measuring 236 cubic inches; the gasoline engine is a naturally aspirated 5.7L overhead-valve V8 of 350 cubic inches. Trim is not really a variable here — one code, W3S042, covers the year. The manual is arranged by system, with procedures, specifications, torque values, wiring diagrams and diagnostics for whichever of the two engines is in the truck.
Engines covered
- 3.9L inline-four (236 cu in) — turbocharged, diesel
- 5.7L V8 (350 cu in) — OHV, naturally aspirated, gasoline
Trims covered
- W3S042
Known issues on the 1997 W3500 Forward. The 1997 W3500 Forward comes through the federal record clean, with no recalls and no owner complaints logged at NHTSA. That leaves the manual to earn its place on ordinary jobs: injection and glow-plug diagnostics on the turbocharged 3.9L diesel, fuel and ignition specifications on the 5.7L V8, brake and steering procedures, driveline and axle torque values, and wiring diagrams for the cab, charging and lighting circuits of a truck that spends its life stopping and starting.
