1999 GMC W7500 Forward Service and Repair Manual
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1999 GMC W7500 Forward Service and Repair Manual
With 1999 came the Isuzu 6HK1, and the GMC W7500 Forward adopted it: a turbocharged 7.8L inline-six diesel of 475 cubic inches in place of the previous 7.1L. The truck continues as the W7R042 straight truck with a low tilt cab, twin to the Chevrolet W7500 Tiltmaster. This service and repair manual is written for the 1999 build, so the procedures, specifications, torque values, wiring diagrams, diagnostics and maintenance schedules for the new engine, its fuel and turbo systems, and the brakes, driveline and cab all apply to this truck.
Engines covered
- 7.8L inline-six (475 cu in) — turbocharged, diesel
Body styles covered
- straight truck, low tilt
Trims covered
- W7R042
Known issues on the 1999 W7500 Forward. No recalls are on federal record for this model year, and NHTSA lists no owner complaints. The engine, brake and driveline procedures in this manual, with their torque values and specifications, cover the routine and preventive work this truck needs.