🏷️ Basic Information

Make:

Jeep

Model:

J20 Standard Cab Pickup

Year:

1979

Chassis Code:

SJ (Full-size Jeep Pickup chassis)

👋 Introduction

Vehicle Class:

Full-size pickup truck, positioned for heavy-duty work and off-road capability.

Era Context:

Part of the robust, long-running Jeep SJ platform, known for its ruggedness and distinctive styling.

Competitors 1979:

Ford F-Series, Chevrolet C/K series, Dodge D Series.

Jeep Advantage:

Renowned 4x4 system (Quadra-Trac), iconic styling, robust chassis.

Body Style:

Standard Cab Pickup

Drivetrain Options:

Available in 2WD and 4WD configurations, with the latter featuring the advanced Quadra-Trac system.

Durability Reputation:

Known for its robust construction and ability to handle demanding tasks.

📋 Manual Details

Primary Coverage:

1979 Jeep J20 Standard Cab Pickup

Secondary Coverage Vehicles:

Likely covers closely related Jeep SJ platform variants of the era, including J-series pickups and Wagoneer/Cherokee models with similar powertrains.

Estimated Pages:

Hundreds of pages (specific count not provided, but characteristic of a full workshop manual)

Type:

Workshop Service Repair Manual

Language:

English

Format:

Downloadable Digital Format (likely PDF)

📖 Manual Coverage

Engine:

Detailed diagnosis, repair, overhaul, and specifications for all available 1979 Jeep J20 engines.

Transmission:

Service and repair procedures for manual and automatic transmissions used in the J20.

Drivetrain:

Front and rear axles, differentials, driveshafts, transfer case (e.g., Quadra-Trac) operation and repair.

Suspension:

Front and rear suspension systems, including springs, shocks, bushings, and alignment procedures.

Brakes:

Hydraulic system, disc and drum brake components, power assist, adjustment, and repair.

Steering:

Power steering system, steering gearbox, linkages, and alignment.

Electrical System:

Wiring diagrams, charging system, starting system, ignition system, lighting, instruments, and accessories.

Fuel System:

Fuel tank, pump, lines, carburetor (e.g., Rochester Quadrajet, Motorcraft), and emissions controls.

Cooling System:

Radiator, fan, water pump, thermostat, hoses, and coolant specifications.

Exhaust System:

Exhaust manifolds, pipes, muffler, and catalytic converter (if applicable).

Body And Chassis:

Frame inspection and repair, body panel adjustments, door mechanisms, glass replacement, interior trim.

HVAC:

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

Maintenance:

Routine maintenance checks, lubrication, filter replacement, fluid changes, tune-ups.

Troubleshooting:

Diagnostic charts, symptom-based troubleshooting guides for various systems.

Repair:

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

Overhaul:

Detailed procedures for rebuilding major components like engines, transmissions, and differentials.

Specifications And Measurements:

Torque specifications, clearances, timing settings, fluid capacities, and diagnostic values.

Wiring Diagrams:

Comprehensive electrical schematics for all vehicle circuits.

Depth:

Comprehensive factory-level coverage suitable for professional technicians and advanced DIY enthusiasts.

📊 Manual Specifications

File Type:

PDF (Portable Document Format)

Searchability:

Likely text-searchable, allowing for quick access to specific information.

Printability:

Designed for high-quality printing, enabling users to create a physical copy.

Ideal Binding For Print:

Spiral or comb binding for lay-flat usability in a workshop environment.

Recommended Paper For Print:

Durable, glossy paper to withstand workshop conditions and preserve image clarity.

⚙️ Engine Specifications

Engine Option 1:

AMC 360 cu in (5.9L) V8

Engine Option 2:

Jeep 258 cu in (4.2L) Inline-6 (less common in J20, more in J10)

Engine 360 Horsepower:

Approx. 175-195 hp (varies by specific tuning and emissions controls)

Engine 360 Torque:

Approx. 280-310 lb-ft (varies by specific tuning and emissions controls)

Carburetor Type 360:

Rochester Quadrajet 4-barrel or Motorcraft 4300D 4-barrel

Fuel Type:

Unleaded gasoline

Bore X Stroke 360:

4.08 in x 3.44 in (103.6 mm x 87.4 mm)

Compression Ratio 360:

Approx. 8.0:1 - 8.5:1

🔧 Transmission

Standard Transmission Option:

e.g., Borg-Warner T-18 4-speed manual

Optional Transmission Option:

e.g., Turbo Hydramatic 700R4 (GM TH400 variant) 3-speed automatic

Transfer Case:

New Process (NP) 205 (gear-driven, part-time) or Quadra-Trac (full-time, chain-driven) 4WD transfer case.

Manual Transmission Fluid:

API GL-4 or GL-5 gear oil (e.g., SAE 80W-90 or 85W-140 depending on climate)

Automatic Transmission Fluid:

Dexron-III (or equivalent ATF)

📐 Dimensions

Wheelbase:

Approx. 129.7 inches (3294 mm)

Length:

Approx. 209.5 inches (5321 mm)

Width:

Approx. 79.5 inches (2019 mm)

Height:

Approx. 66.7 inches (1694 mm) (varies with trim/suspension)

Curb Weight:

Approx. 4,000 - 4,500 lbs (1814 - 2041 kg) (varies significantly with configuration)

Payload Capacity:

Up to 2500 lbs (1134 kg) for J20 models.

Gvwr:

Approx. 6,000 - 7,000 lbs (2722 - 3175 kg)

Standard Tire Size:

e.g., 9.50R16.5LT, 235/85R16

Wheel Bolt Pattern:

5x5.5 inch (5x139.7 mm)

🛡️ Safety Features

Crash Test Data:

No standardized crash test data available for this era of heavy-duty trucks in the modern sense (e.g., NHTSA ratings).

Braking System:

Front disc brakes, rear drum brakes. Power assist likely standard on J20.

Seat Belts:

Standard lap and shoulder belts (driver and passenger).

Roll Bar:

Internal cab structure provides some rollover protection, but not a designated roll bar.

💡 Technology Features

Radio:

Optional AM/FM radio, potentially with cassette player towards the end of the model's run.

ABS:

Anti-lock Braking System (ABS) was not available on this model.

Connectivity Features:

None (analog gauges and controls).

🔧 Maintenance

Oil Change Interval:

Typically every 3,000 miles or 3 months (based on contemporary recommendations).

Tune Up Interval:

Every 12,000 - 24,000 miles, including spark plugs, points (if applicable), and filter checks.

Transmission Fluid Change:

Every 24,000 - 36,000 miles or as per manual recommendations.

Engine Oil Specification:

API SF, SG, or SH service category. Viscosity: 10W-30 or 10W-40 (consider 15W-40 for heavy-duty use).

Coolant Specification:

Ethylene glycol-based antifreeze. 50/50 mix with distilled water.

Brake Fluid Specification:

DOT 3 or DOT 4 hydraulic brake fluid.

Common Wear Items:

U-joints, leaf spring bushings, alternator, fuel pump, carburetor issues, exhaust manifold leaks.

Electrical Gremlins:

Aging wiring harnesses and connections can lead to intermittent electrical problems.

Quadratrac Maintenance:

Regular inspection and proper fluid levels in the Quadra-Trac system are crucial for longevity.

📚 Vehicle History

Jeep Legacy:

Jeep's long history of producing rugged, off-road capable vehicles dating back to WWII.

J-Series Lineage:

The J-series pickup truck line, including the J20, was part of the full-size Jeep (SJ) platform, which also included the Wagoneer and Cherokee. This platform was produced with minimal changes from 1963 to 1991.

J20 Distinction:

The J20 designation typically signified a heavier-duty version of the J-series pickup, often with a higher GVWR and payload capacity compared to the J10.

Manufacturer:

Kaiser-Jeep / American Motors Corporation (AMC)

Manufacturing Plant:

Primarily Toledo, Ohio.

🏆 Awards & Recognition

Off Road Accolades:

Jeep vehicles, including the J-series, are consistently recognized for their off-road prowess and go-anywhere capability.

Vintage Truck Status:

Considered a classic American workhorse and a desirable vintage truck for enthusiasts and collectors.