1991 GMC C2500 Service and Repair Manual

This factory service and repair manual for the 1991 GMC C2500 takes in five engines: the 4.3L V6, the 5.0L, 5.7L and 7.4L gasoline V8s and the 6.2L diesel V8, every one overhead-valve and naturally aspirated. The 7.4L at the top and the V6 at the bottom are far enough apart that little carries over between them, which is why cooling, fueling and torque data are given per engine. Bodies are the standard cab pickup, the extended cab pickup and the cab and chassis, in three Sierra trims.

Engines covered

• 5.0L V8 (305 cu in) — OHV, naturally aspirated, gasoline
• 7.4L V8 (454 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
• 2-door cab & chassis

Trims covered

• Sierra
• Sierra SLE
• Sierra SLX

Known issues on the 1991 C2500. Two recalls stand against this model year. In one, heat in the transmission beyond what the design allowed for can force fluid out of the vent tube, where it may ignite. In the other, replacement oil filters sold for these engines could seal inadequately and allow engine oil to escape, again with a fire risk. Four owner complaints are logged with NHTSA, one each on visibility, the power train and the seat belts. Transmission service, lubrication specifications, wiper and glass work and restraint procedures are all documented here with their torque values.