Systems Covered Engine:
Engine mechanical, lubrication, cooling, fuel, ignition, emissions control, starting, charging
Systems Covered Transmission:
Automatic transmission service and repair (likely AOD/AODE variations for 1991)
Systems Covered Drivetrain:
Driveshaft, axles, rear axle assembly
Systems Covered Brakes:
Brake system hydraulics, components, anti-lock brake system (if equipped)
Systems Covered Suspension:
Front and rear suspension, steering system
Systems Covered Electrical:
Wiring diagrams, lighting, instrumentation, power distribution, body electrical components
Systems Covered HVAC:
Heating, ventilation, and air conditioning (HVAC) system
Systems Covered Body:
Body panels, interior trim, doors, windows, glass, seats
Systems Covered Exhaust:
Exhaust system components and diagnosis.
Systems Covered Fuel:
Fuel tank, fuel pump, fuel lines, fuel filter, fuel injection system.
Systems Covered Ignition:
Distributor, ignition coil, spark plugs, spark plug wires, ignition module.
Procedures Included Maintenance:
Routine maintenance, fluid changes, filter replacements, tune-ups
Procedures Included Diagnostics:
Troubleshooting guides, diagnostic trouble codes (DTCs) if applicable, symptom-based diagnostics
Procedures Included Repair:
Component removal and installation, system repairs, adjustments
Procedures Included Specifications:
Torque specifications, clearances, alignments, electrical values
Procedures Included Body Repair:
Front and rear bumper replacement, fender repairs, door panel removal and installation, hood and trunk lid adjustments.
Procedures Included Steering Repair:
Steering column overhaul, power steering pump and rack replacement.
Procedures Included Engine Rebuild:
Engine teardown, inspection, assembly, piston and ring replacement, bearing replacement, cylinder head overhaul.
Technical Depth:
Factory-derived, comprehensive, suitable for DIY and professional technicians
Technical Depth Wiring:
Detailed wiring diagrams for all electrical systems, including component location and pin-out data.
Technical Depth Diagnostics:
Comprehensive diagnostic procedures for all major systems, including flowcharts and symptom-to-cause mappings.
Technical Depth Specifications:
Precise torque values, diagnostic tool usage, measurement specifications for all mechanical and electrical components.
Maintenance Oil Change Interval:
Every 3,000-5,000 miles or 6 months (typical for this era, consult manual for specific recommendations)
Maintenance Tune Up Interval:
Typically every 30,000 miles, including spark plug replacement and inspection of ignition components.
Fluid Engine Oil Spec:
SAE 5W-30 or 5W-30 Synthetic (check manual for exact specification and viscosity index)
Fluid Transmission Oil Spec:
Mercon ATF (Automatic Transmission Fluid)
Fluid Coolant Spec:
Ford Premium Engine Coolant (Green) or equivalent ethylene glycol based coolant
Fluid Brake Fluid Spec:
DOT 3 Brake Fluid
Fluid Power Steering Spec:
Mercon ATF or equivalent power steering fluid.
Known Issues Electrical:
Flickering dashboard lights, power window/lock issues, ABS sensor failures.
Known Issues Suspension:
Wear in ball joints, tie rod ends, and bushings due to the independent rear suspension design. Potential for IRS vibration issues if not maintained.
Known Issues Engine:
Spark plug blow-out on 5.0L HO engines (requiring thread inserts), potential for oil leaks, fuel injector issues.
Known Issues HVAC:
Leaking heater cores, AC compressor failures, blend door actuator issues.
Brand Heritage:
Mercury, a division of Ford Motor Company, was positioned as a premium brand, offering a balance of style, comfort, and performance.
Model Evolution:
The 1991 Cougar marked the second year of the sixth generation, which was a significant departure from earlier models, adopting the MN12 platform for improved handling and a more European sports coupe aesthetic.
Model Evolution Mn12 Platform:
The MN12 platform was a significant engineering effort by Ford, featuring a much stiffer chassis and sophisticated suspension compared to previous front-wheel drive personal luxury coupes.
Production Location:
Ford's Wixom, Michigan assembly plant.
