Market Positioning:
The definitive guide for owners and technicians of the 1991 Chevrolet C/K series trucks, offering dealership-level repair and maintenance expertise.
Competitive Advantage:
This manual provides vehicle-specific information, unlike generic guides, ensuring accuracy and efficiency in diagnostics and repairs.
Key Features Highlight:
Directly sourced from manufacturer-provided data, this manual mirrors the information used by authorized Chevrolet service centers.
Engine Systems:
Engine mechanical, lubrication, cooling, fuel, exhaust, ignition, emissions control
Transmission Drivetrain:
Manual and automatic transmissions, transfer case (4WD), driveshafts, axles, differentials
Brake Systems:
Front disc brakes, rear drum brakes, parking brake, hydraulic system, ABS (if equipped)
Suspension Steering:
Independent front suspension (IFS), leaf spring rear suspension, steering gearbox, power steering system
Electrical Electronics:
Battery, charging system, starting system, lighting, instrumentation, engine control module (ECM), body electrical, wiring diagrams
Body Chassis:
Frame, body panels, doors, windows, interior trim, HVAC system, seats, bumpers
Diagnostic Procedures:
Troubleshooting guides, diagnostic trouble codes (DTCs), symptom-based diagnostics
Maintenance Procedures:
Fluid changes, filter replacements, tune-ups, lubrication services
Repair Procedures:
Component removal and installation, overhaul procedures, adjustments
Specification Tables:
Torque specifications, clearances, fluid capacities, resistance values
Depth Of Coverage:
Comprehensive (from basic maintenance to complete engine/transmission rebuilds and complex diagnostics)
Engine Options:
4.3L V6 (VIN Z, W), 5.0L V8 (VIN E), 5.7L V8 (VIN K), 7.4L V8 (VIN P)
Horsepower Range:
Approx. 160-230 hp (depending on engine)
Torque Range:
Approx. 230-370 lb-ft (depending on engine)
Fuel Delivery:
Throttle Body Injection (TBI) or Multi-Port Fuel Injection (MPFI) depending on engine
V8 Engine Code K:
5.7L V8 (VIN K) - L05
V8 Engine Code E:
5.0L V8 (VIN E) - L03
V6 Engine Code Z:
4.3L V6 (VIN Z) - LB4
V8 Engine Code P:
7.4L V8 (VIN P) - L19
Standard Transmission:
4-speed Manual (NV4500 for some heavy-duty models)
Optional Transmission:
4-speed Automatic (700R4/4L60, 4L80E for heavy-duty models)
4Wd Transfer Case:
New Process 208 (part-time manual shift) or NP241 (part-time electronic shift)
Automatic Transmission Fluid:
Dexron-III ATF (or equivalent)
Manual Transmission Fluid:
GL-4 Gear Lubricant (specific viscosity varies by model)
Body Styles:
Regular Cab, Extended Cab, Crew Cab; Fleetside (bed) and Stepside (bed)
Wheelbase Options:
117.5" (std cab), 131.5" (ext cab), 143" (long bed), 155.5" (dually)
Gvwr Range:
5,500 - 10,000+ lbs (depending on configuration)
Curb Weight Range:
4,000 - 5,500+ lbs (depending on configuration)
Safety Ratings:
NHTSA ratings for this era are generally lower by modern standards. Consult specific recall data for safety concerns.
Active Safety Features:
Anti-lock Braking System (ABS) was optional on some models, particularly rear-wheel anti-lock.
Passive Safety Features:
Seat belts, reinforced safety cage construction.
Infotainment Features:
AM/FM radio with cassette player, optional CD player, manual or power windows and locks, basic climate control.
Driver Assistance Systems:
Limited driver assistance features by modern standards. Cruise control was common.
Connectivity Options:
No modern connectivity features like Bluetooth or USB. Analog systems.
Oil Change Interval:
Typically 3,000-5,000 miles or 6 months, whichever comes first (consult manual for specific engine recommendations).
Tune Up Interval:
Spark plugs and filters usually recommended every 30,000-60,000 miles depending on component type and engine.
Engine Oil Specification:
API SF/CD or SG/CD; Viscosity: 5W-30, 10W-30, or 10W-40 depending on ambient temperature (consult manual).
Coolant Specification:
Ethylene glycol based coolant (e.g., Dex-Cool equivalent for later versions, but typically green conventional coolant for 1991).
Brake Fluid Specification:
DOT 3 Hydraulic Brake Fluid
Common Wear Items:
Ball joints, tie rod ends, idler/pitman arms (suspension wear), intake manifold gaskets (leaks), catalytic converter (clogging/failure), fuel pump (in-tank).
Electrical Gremlins:
Dashboard warning lights, HVAC blower motor issues, fuel gauge inaccuracies can occur with age.
Engine Specific Concerns:
4.3L V6 (LB4) can develop intake manifold gasket leaks; older 5.0L and 5.7L V8s may experience valve guide wear.
Air Filter Example:
ACDelco A3021C (example, verify for specific engine)
Oil Filter Example:
ACDelco PF25 (example, verify for specific engine)
Chevrolet Truck Heritage:
Chevrolet has a long-standing reputation for building durable and capable pickup trucks dating back to the 1910s.
C K Generation Introduction:
The 1991 model year represents the second year of the GMT400 platform, a significant redesign for Chevrolet's full-size trucks, featuring a more aerodynamic and modern design.
Production Period Gmt400:
GMT400 platform produced from 1988 (light duty) and 1991 (heavy duty) through 2000.
Manufacturing Locations:
Various GM assembly plants in North America.
Industry Recognition:
While specific awards for the 1991 model may not be widely publicized, the GMT400 platform was a critical success for GM, reviving their truck sales and setting new standards for comfort and performance in the segment.
Reliability Perception:
Generally considered robust and reliable trucks when properly maintained, with strong aftermarket support.
