1991 GMC C6000 Topkick Service and Repair Manual
This factory service and repair manual for the 1991 GMC C6000 Topkick deals with a truck sold one way — as a 2-door conventional cab and chassis under trim code C6H042 — but with a genuine choice under the hood. Gasoline buyers took either the 6.0L overhead-valve V8 of 366 cubic inches or the 7.0L overhead-valve V8 of 427 cubic inches, both naturally aspirated. The diesel option was a turbocharged 6.6L overhead-valve inline-six of 403 cubic inches. All three are documented with their own procedures, specifications and torque values.
Engines covered
- 6.0L V8 (366 cu in) — OHV, naturally aspirated, gasoline
- 7.0L V8 (427 cu in) — OHV, naturally aspirated, gasoline
- 6.6L inline-six (403 cu in) — OHV, turbocharged, diesel
Body styles covered
- 2-door cab & chassis, conventional
Trims covered
- C6H042
Known issues on the 1991 C6000 Topkick. Federal records hold nothing against the 1991 C6000 Topkick: no recalls, no owner complaints. In practice a truck like this is judged by how well its last owner kept up with the schedule, and this manual is the reference for that work. It gives the service procedures and specifications for the two gasoline V8s and the turbocharged diesel six, torque values for the fasteners on each, wiring diagrams for the cab and chassis circuits, and diagnostics for the systems those circuits control.
