1991 GMC C1500 Service and Repair Manual

This factory service and repair manual for the 1991 GMC C1500 works through a truck whose variety is all under the hood: one chassis, two cab styles and the Sierra, Sierra SLE and Sierra SLX trims, but four different engines. The 4.3L V6 and the 5.0L and 5.7L V8s burn gasoline, the 6.2L V8 is a diesel, and all four are overhead-valve and naturally aspirated. Torque values, clearances, timing data and diagnostic routines are given per engine rather than averaged across the range.

Engines covered

• 5.0L V8 (305 cu in) — OHV, naturally aspirated, gasoline
• 6.2L V8 (379 cu in) — OHV, naturally aspirated, diesel
• 4.3L V6 (262 cu in) — OHV, naturally aspirated, gasoline
• 5.7L V8 (350 cu in) — OHV, naturally aspirated, gasoline

Body styles covered

• 2-door standard cab pickup
• 2-door extended cab pickup

Trims covered

• Sierra
• Sierra SLE
• Sierra SLX

Known issues on the 1991 C1500. A single recall is recorded against this model year, and it concerns the automatic transmission: heat beyond what the design allowed for can push fluid out through the vent tube, where it may ignite. Five owner complaints are logged with NHTSA, spread thinly across visibility, tires and the service brakes with one entry each. None of that suggests a single weak point, so the transmission cooling and fluid checks, the wiper and glass procedures and the brake specifications are all worth having in front of you before the work starts.