Segment:
Full-size pickup truck, targeting utility, work, and off-road enthusiasts.
Competitors:
Competed against Ford F-Series, Chevrolet C/K Series, and Dodge Ram trucks of the era.
Features:
Rugged construction, robust 4x4 capability (optional), spacious standard cab, and robust powertrain options characteristic of Jeep's off-road heritage.
Systems:
Engine, Transmission, Drivetrain, Suspension, Steering, Brakes, Electrical System, Fuel System, Cooling System, Exhaust System, Body and Chassis, Interior, HVAC, Emissions Control
Pages:
Hundreds (exact count not specified in product info, but implied to be comprehensive)
Type:
Factory Service Repair Manual
Engine:
Detailed diagnosis, repair, overhaul, and specifications for all J20 engine options.
Transmission:
Repair and overhaul procedures for manual and automatic transmissions, including clutch, transfer case, and drive axle components.
Brakes:
Front disc and rear drum brake system diagnosis, repair, and specifications, including hydraulic system components.
Electrical System:
Complete wiring diagrams, component testing, diagnosis, and repair for all electrical systems, including lighting, ignition, charging, and accessories.
Fuel System:
Carburetor and fuel delivery system diagnosis, adjustment, and repair.
Suspension Steering:
Front and rear suspension component inspection, replacement, and alignment specifications. Steering system diagnosis and repair.
Body Chassis:
Frame and body panel repair, door and window mechanisms, and exterior trim.
Emissions Control:
Details on emissions control systems relevant to 1979 regulations.
Maintenance:
Scheduled maintenance, fluid checks and changes, filter replacements, lubrication points.
Troubleshooting:
Diagnostic flowcharts and symptom-based troubleshooting for common and complex issues.
Repair:
Step-by-step repair instructions for all major components and systems.
Overhaul:
Detailed procedures for engine, transmission, and axle overhauls.
Engine Rebuild:
Detailed steps for engine disassembly, inspection, measurement, and reassembly, including torque specifications and clearances.
Transmission Rebuild:
Comprehensive instructions for rebuilding both automatic and manual transmissions, including clutch replacement and transfer case overhaul.
Diagnostics:
Includes diagnostic charts for electrical, fuel, ignition, and mechanical systems.
Body Repair:
Guidance on frame straightening, panel replacement, and bodywork adjustments.
HVAC Repair:
Service and repair procedures for the heating, ventilation, and air conditioning system.
Depth:
Comprehensive: Covers everything from routine maintenance to complete engine and transmission rebuilds, including diagnostic procedures and specifications.
Diagnostic Codes:
While OBD-I or OBD-II codes were not in use, the manual provides symptom-based troubleshooting and diagnostic procedures for component testing.
Specifications Charts:
Extensive charts for torque values, clearances, fluid capacities, and electrical resistance.
Engine Option 1:
AMC 360 V8 (5.9L) - Known for its torque and power.
Engine Option 2:
AMC 258 Inline-6 (4.2L) - A reliable and torquey inline-six.
Horsepower 360:
Approx. 170-190 hp (gross, depending on specific configuration and tune)
Torque 360:
Approx. 280-300 lb-ft (gross, depending on specific configuration and tune)
Horsepower 258:
Approx. 110-125 hp (gross, depending on specific configuration and tune)
Torque 258:
Approx. 200-215 lb-ft (gross, depending on specific configuration and tune)
Horsepower 304:
Approx. 125-150 hp (gross)
Torque 304:
Approx. 230-250 lb-ft (gross)
Fuel Delivery:
Rochester Quadra-Jet 4-barrel carburetor for V8; Carter YF 1-barrel carburetor for I6 (typical configurations).
Fuel Type:
Unleaded gasoline
Engine Option 3 Name:
AMC 304 V8 (5.0L)
Transmission Type:
4-speed manual (New Process NP435 common)
Transmission Type Optional:
3-speed automatic (TorqueFlite A727)
Transfer Case:
Dana 20 (part-time 4WD system, common with 4x4 models)
Axles:
Dana 44 front axle, Dana 60 or 70 rear axle (depending on GVW and configuration)
Oil Change Interval:
Typically every 3,000 - 5,000 miles (refer to manual for specific engine and oil type).
Tune Up Interval:
Recommended every 12,000 - 15,000 miles or annually.
Engine Oil Type:
API Service SF or SG rated oil, viscosity typically 10W-30 or 10W-40 (refer to manual for precise recommendation).
Coolant Type:
Ethylene glycol-based antifreeze/coolant, typically a 50/50 mix with distilled water.
Brake Fluid Type:
DOT 3 or DOT 4 hydraulic brake fluid.
Transmission Fluid Automatic:
Dexron-III (or equivalent) automatic transmission fluid.
Transmission Fluid Manual:
API GL-4 or GL-5 gear oil, viscosity typically 80W-90.
Common Problems:
Rust (especially body panels, fenders, rocker panels), carburetor tuning, ignition system reliability, aging fuel lines, cooling system leaks, and vacuum hose degradation.
Electrical Issues:
Corroded grounds, aging wiring harnesses, and issues with older electrical components.
Heritage:
Jeep, a brand synonymous with ruggedness and off-road capability since WWII.
Predecessors:
Evolved from the Jeep Gladiator (SJ) pickup trucks of earlier generations.
Platform:
Shared platform with the Jeep Wagoneer (SJ) SUV.
Production Period:
J-series trucks were produced from 1962 to 1987, with the J20 being a variant focused on heavy-duty applications.
