🏷️ Basic Information

Make:

Chevrolet

Model:

Corvette C4

Year:

1991

Model Code:

C4

Market Segment:

Sports Car / Grand Tourer

👋 Introduction

Positioning:

The Chevrolet Corvette C4 represented America's premier sports car in 1991, competing with European exotics and high-performance coupes. This manual serves enthusiasts and professional technicians looking to maintain or restore this iconic vehicle.

Competitors:

Porsche 944, BMW 8 Series, Nissan 300ZX (Z32), Toyota Supra (Mk3).

Value Proposition:

Empowers owners to perform their own maintenance and repairs, saving significant costs and fostering a deeper understanding of their vehicle.

Ease Of Use:

Features step-by-step instructions and illustrations for simplified repair processes.

📋 Manual Details

Primary Coverage:

Complete Service, Repair, and Workshop Procedures

Models Covered:

All 1991 Chevrolet Corvette C4 models, trims, and engine/transmission configurations.

Estimated Pages:

Approximately 1,500-2,500 pages (typical for full factory service manuals).

Type:

Workshop Service Repair Manual

Language:

English

Format:

Downloadable Digital Format (PDF)

📖 Manual Coverage

Engine:

Engine mechanical, lubrication, cooling, fuel delivery, ignition, emissions control, starting, charging.

Transmission:

Manual and automatic transmission service, repair, and overhaul.

Drivetrain:

Driveshaft, differential, axles, and suspension components.

Brakes:

Hydraulic system, anti-lock braking system (ABS), parking brake, component replacement.

Steering:

Power steering system, steering linkage, wheel alignment.

Electrical:

Battery, charging system, starting system, lighting, instrument cluster, power accessories, body control modules, wiring diagrams.

HVAC:

Heating, ventilation, and air conditioning system diagnosis and repair.

Body:

Body panels, doors, glass, interior trim, exterior trim, bumpers, seals.

Chassis:

Frame, subframes, mountings, and related components.

Exhaust System:

Diagnosis and repair of exhaust components.

Fuel System:

Fuel pump, injectors, lines, tank, and pressure regulation.

Maintenance:

Scheduled maintenance, fluid changes, filter replacements, lubrication.

Diagnostics:

Troubleshooting guides, diagnostic trouble codes (DTCs), component testing procedures.

Repair:

Step-by-step instructions for component removal, disassembly, repair, reassembly, and installation.

Overhaul:

Detailed procedures for engine, transmission, and differential rebuilds.

Adjustment:

Adjustment procedures for engine timing, idle speed, clutch, brakes, etc.

Specifications:

Torque specifications, clearances, fluid capacities, electrical parameters.

Wheel Alignment:

Specifications and procedures for front and rear wheel alignment.

Air Conditioning Recharge:

Procedures for refrigerant and oil servicing (referencing R134a transition or R12 depending on specific vehicle build date and region).

Depth:

Comprehensive: Covers everything from routine maintenance and basic repairs to advanced diagnostics and complete component overhauls.

Wiring Diagrams:

Includes detailed electrical wiring diagrams for all systems.

Troubleshooting Charts:

Includes comprehensive troubleshooting charts and flow diagrams.

📊 Manual Specifications

File Type:

PDF

Searchable:

Yes (typically)

Quality:

High Quality (Digital)

Binding:

N/A (Downloadable)

Paper:

N/A (Digital)

Device Compatibility:

PC, Mac, Tablets, Smartphones

Software Requirement:

Adobe Reader (Free)

⚙️ Engine Specifications

Engine Name:

L98 (350 ci)

Engine Type:

V8, Pushrod OHV

Displacement:

5.7 Liters (350 Cubic Inches)

Bore X Stroke:

4.00 in x 3.48 in (101.6 mm x 88.4 mm)

Horsepower:

230-245 hp @ 4,000-4,400 rpm (depending on specific configuration)

Torque:

315-345 lb-ft @ 3,200-3,500 rpm (depending on specific configuration)

Fuel Delivery:

Bosch Tuned Port Injection (TPI) with Sequential Fuel Injection (SFI) for some late models/california.

Fuel Type:

Unleaded Premium Gasoline (91+ Octane Recommended)

Coolant Capacity:

Approx. 13.7 Quarts (13.0 Liters)

Oil Capacity With Filter:

5 Quarts (4.7 Liters)

ECU:

Engine Control Unit (ECU) with diagnostic capabilities.

🔧 Transmission

Type:

4-Speed Automatic (700R4 / 4L60)

Type:

6-Speed Manual (ZF S6-40)

Automatic Features:

Electronic control, overdrive.

Manual Features:

Close-ratio, robust design for performance driving.

Automatic Fluid Type:

Dexron III ATF (or equivalent)

Manual Fluid Type:

GM Synchromesh Transmission Fluid (or equivalent)

Automatic Capacity:

Approx. 4.5 Quarts (4.3 Liters) for dry fill.

📐 Dimensions

Length:

178.3 inches (4,529 mm)

Width:

70.4 inches (1,788 mm)

Height:

46.4 inches (1,179 mm)

Wheelbase:

96.2 inches (2,443 mm)

Curb Weight:

Approx. 3,200-3,400 lbs (1,451-1,542 kg)

🛡️ Safety Features

NHTSA Rating:

N/A (Ratings standards varied significantly in this era)

ABS:

Standard Anti-lock Braking System (ABS)

Airbags:

Driver-side airbag (introduced in 1990, standard for 1991)

Seatbelts:

3-point inertia reel seat belts

Rollover Protection:

Integral roll bar structure behind seats

💡 Technology Features

Audio System:

Delco-Bose premium sound system often available, AM/FM stereo cassette player with optional CD player.

Climate Control:

Manual or optional electronic automatic climate control (EATC).

Cruise Control:

Standard

Connectivity Features:

None (modern connectivity features not present)

🔧 Maintenance

Oil Change:

Every 3,000-7,500 miles (5,000-12,000 km) or 6-12 months, depending on driving conditions and oil type.

Transmission Fluid Change:

Every 30,000-50,000 miles (48,000-80,000 km) for automatic, every 50,000-100,000 miles (80,000-160,000 km) for manual.

Spark Plug Replacement:

Every 30,000-60,000 miles (48,000-96,000 km), depending on plug type.

Coolant Flush:

Every 30,000-50,000 miles (48,000-80,000 km) or 2-3 years.

Engine Oil Viscosity:

10W-30 recommended for most conditions (check manual for specific temperature ranges).

Brake Fluid Type:

DOT 3

Power Steering Fluid:

GM Power Steering Fluid (or Dexron II/III ATF)

Common Problems:

Aging plastic interior components, HVAC blower motor failure, rear main seal leaks, transmission clutch wear (manual), early ABS sensor issues.

Idle Speed:

Refer to manual, typically around 600-700 RPM for automatic, 700-800 RPM for manual.

📚 Vehicle History

Heritage:

Chevrolet has a long history of performance vehicles, with the Corvette being its flagship sports car since 1953.

C4 Generation Years:

1984-1996

1991 Updates:

Introduction of improved steering rack, standard driver-side airbag, updated interior trim, and revised option packages. The LT1 engine was introduced in 1992.

Manufacturing Location:

Bowling Green, Kentucky, USA

🏆 Awards & Recognition

Automotive Awards:

Corvette consistently ranked high in performance and design categories during its C4 generation. Specific awards for the 1991 model would be reflected in contemporary automotive publications.