Model:
Sierra RS Cosworth
Years Covered:
1986, 1987, 1988, 1989, 1990, 1991, 1992
Chassis Code:
GBC (3-door hatchback), GDF (Sapphire 4-door sedan)
Positioning:
The Ford Sierra RS Cosworth was a homologation special, designed to compete in Group A touring car racing. It was positioned as a high-performance, driver-focused sports sedan, targeting enthusiasts and those seeking motorsport pedigree.
Competitors:
BMW M3 E30, Mercedes-Benz 190E 2.3-16 Cosworth, Opel Kadett GSi, Audi Quattro.
Performance Focus:
The RS Cosworth was renowned for its aggressive styling, powerful turbocharged engine, advanced chassis dynamics, and motorsport heritage.
Manual Value Proposition:
This manual provides essential technical data and step-by-step procedures required for the proper maintenance, repair, and restoration of this iconic performance vehicle, enabling owners to keep their RS Cosworth in optimal condition.
Engine:
2.0L I4 DOHC (Cosworth YBG), Turbocharging System, Fuel Injection System (Bosch Motronic), Ignition System, Cooling System, Lubrication System.
Drivetrain:
5-speed Manual Transmission (MT75), Limited Slip Differential (LSD), Clutch System, Driveshafts, Rear Axle.
Suspension Steering:
Front Independent Suspension (MacPherson Struts), Rear Independent Suspension (Multi-link), Power Assisted Steering System.
Brakes:
Front Ventilated Disc Brakes, Rear Disc Brakes, Anti-lock Braking System (ABS) - where equipped.
Electrical Electronics:
Battery, Charging System, Starting System, Lighting System, Ignition System, Instrumentation, Engine Control Unit (ECU), Wiring Diagrams, Fuses and Relays.
Body Chassis:
Body Construction, Exterior Panels, Doors, Hood, Trunk, Bumpers, Interior Trim, Seat Removal and Installation, Glass Replacement.
Maintenance:
Scheduled maintenance, oil changes, filter replacements, fluid checks and changes, spark plug replacement, belt inspection and replacement.
Repair:
Engine overhaul, transmission repair, brake system service, suspension component replacement, electrical system diagnostics and repair, body panel repair.
Troubleshooting:
Systematic diagnostic procedures for common and uncommon issues, fault code interpretation (if applicable), symptom-based troubleshooting.
Disassembly Assembly:
Detailed step-by-step instructions for component removal, disassembly, inspection, repair, reassembly, and installation.
Specifications:
Torque specifications for all fasteners, fluid capacities, wear limits, adjustment procedures, critical measurements.
Depth:
From basic routine maintenance to complete engine and drivetrain rebuilds, including advanced diagnostics and component-level repair.
Engine Type:
Inline 4-cylinder, turbocharged, DOHC (Dual Overhead Camshaft)
Displacement:
1993 cc (2.0 Liters)
Bore X Stroke:
90.8 mm x 77.0 mm
Valve Train:
4 valves per cylinder, belt-driven DOHC
Horsepower Ps:
204 PS (150 kW; 201 hp) at 6000 rpm
Torque Lb-Ft:
214 lb-ft (290 Nm) at 3500 rpm
Induction:
Bosch L-Jetronic fuel injection with Garrett T03 turbocharger and intercooler.
Fuel Type:
Unleaded Premium (95 RON minimum recommended)
Fuel Pump Pressure:
Typically 3.0-3.5 bar (43.5-50.8 psi), refer to manual for exact specification.
Length:
4420 mm (174.0 in) for 3-door hatchback, 4488 mm (176.7 in) for Sapphire sedan.
Height:
1380 mm (54.3 in) for 3-door hatchback, 1375 mm (54.1 in) for Sapphire sedan.
Wheelbase:
2600 mm (102.4 in)
Curb Weight Kg:
Approximately 1270-1300 kg (2800-2866 lbs) depending on body style and equipment.
Gross Vehicle Weight Rating:
Refer to manual for specific GVWR, typically around 1700 kg.
Era Safety Standards:
Met contemporary European safety standards for its time; advanced for its class.
ABS:
Anti-lock Braking System (ABS) available as an option on some models, standard on later Sapphire variants.
Limited Slip Differential:
Standard LSD enhances traction and stability during acceleration and cornering.
Seatbelts:
Three-point inertia-reel seatbelts for front occupants, lap belts for rear occupants.
Body Structure:
Reinforced safety cage, energy-absorbing crumple zones.
Audio System:
Typically featured a Ford radio/cassette player, often with optional amplifier and uprated speakers. Aftermarket head units are common upgrades.
Instrumentation:
Comprehensive analogue gauges including tachometer, speedometer, oil pressure, oil temperature, boost gauge, and fuel level.
ABS:
Optional or standard on later models, providing enhanced braking control.
Power Steering:
Hydraulic power-assisted steering for improved maneuverability.
Modern Connectivity:
None from the factory; modern connectivity requires aftermarket integration.
Oil Change:
Every 6,000 miles (10,000 km) or 6 months, whichever comes first. Use specified oil viscosity and type.
Air Filter:
Inspect every 6,000 miles (10,000 km), replace as needed or at least annually. Refer to manual for specific part number.
Spark Plugs:
Replace every 12,000 miles (20,000 km) or 12 months. Use specified spark plug type (e.g., NGK BPR6ES or equivalent).
Timing Belt:
Replace every 36,000 miles (60,000 km) or 3 years, whichever comes first. Critical component, failure can cause severe engine damage. Always replace tensioner and idler pulleys.
Engine Oil:
API SG/SH rated, viscosity SAE 10W-40 or 5W-40. Capacity 5.2 liters (with filter). Refer to manual for exact specification and approved brands.
Coolant:
50/50 mix of ethylene glycol coolant and distilled water. Capacity approximately 8.5 liters. Use Ford specification coolant.
Transmission Fluid:
Manual Transmission Fluid (MTF), e.g., Ford WSD-M2C200-B or equivalent. Capacity approx. 2.0 liters. Refer to manual for precise specification.
Brake Fluid:
DOT 3 or DOT 4 brake fluid. Always use fresh, sealed fluid.
Power Steering Fluid:
Ford specification power steering fluid or ATF Dexron II/III. Capacity approx. 1.0 liter.
Turbo Failure:
Turbocharger seals can degrade over time, leading to oil consumption and smoke. Regular oil changes are crucial for turbo longevity.
Cylinder Head Gasket:
Overheating can lead to cylinder head gasket failure. Ensure cooling system is in good order. Early detection of coolant loss is vital.
Rust:
Like many cars of this era, rust can be an issue, particularly on wheel arches, sills, and around the battery tray. Thorough inspection and preventative measures are recommended.
Electrical Gremlins:
Older wiring harnesses and connectors can corrode or degrade, leading to intermittent electrical faults. Wiring diagrams in the manual are essential for diagnosis.
Suspension Wear:
Bushings and ball joints in the suspension can wear out, affecting handling and ride quality. Regular inspection and replacement are necessary.
Ford Performance:
Ford has a long history of performance vehicles, and the RS (Rallye Sport) badge represents its most potent and motorsport-oriented models.
Sierra Platform:
The Sierra was introduced in 1982 as a replacement for the Ford Taunus and Cortina. It featured a distinctive aerodynamic 'jelly mould' design and innovative 'Procon Ten' cable safety system.
Cosworth Collaboration:
The RS Cosworth variant was developed in conjunction with Cosworth Engineering, utilizing their renowned 2.0-liter turbocharged Cosworth YBG engine. It was built as a homologation special for Group A touring car racing.
Production Years:
1986-1992
Production Locations:
Genk, Belgium (Ford Europe assembly plant).
Production Numbers:
Approximately 29,095 units (including 5,000 RS500 homologation specials).
Motorsport Success:
The Sierra RS Cosworth achieved significant success in various motorsport disciplines, particularly in touring car championships globally, cementing its legendary status.
Performance Car Status:
Widely regarded as one of the most iconic and capable performance cars of its era, a true homologation special that translated motorsport success to the road.
