This factory service and repair manual for the 1990 GMC W7500 Forward has to serve three engine choices, all turbocharged diesel inline-sixes: 6.5L at 396 cubic inches, 8.4L at 513 and 5.8L at 353. Body and trim coverage does not vary, being a low tilt straight truck in the W7R042 code, so the branching happens on the engine side alone. The result is one book that a shop can use whichever of the three is fitted.
Engines covered
- 6.5L inline-six (396 cu in) — turbocharged, diesel
- 8.4L inline-six (513 cu in) — turbocharged, diesel
- 5.8L inline-six (353 cu in) — turbocharged, diesel
Body styles covered
- Straight truck, low tilt
Trims covered
- W7R042
Known issues on the 1990 W7500 Forward. NHTSA's record on the 1990 W7500 Forward is clean, showing no recalls and no owner complaints. With no defect pattern to work around, the manual's practical use is on the three turbocharged sixes and the chassis they share, through diagnostic procedures for symptoms, the specifications a repair has to achieve, torque values for reassembly, and wiring diagrams for the electrical circuits.
