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Ford Sierra (1982 to 1993)

By Jon Cosson · Last checked 13 October 2026

The Sierra replaced the Cortina in 1982 and the performance versions, from XR4i to RS Cosworth, are the ones most often seen at auction. Check rust, history and identity closely. Cosworths in particular were widely stolen, crashed, modified and copied, so the paperwork and numbers matter as much as the paint.

At a glance

Years: 1982 to 1993 (XR4i 1983, XR4x4 1985, RS Cosworth 1986, RS500 1987, Sapphire RS Cosworth 1988, Sapphire RS Cosworth 4x4 1990)
Body styles: three-door and five-door hatchback, five-door estate, four-door Sapphire saloon
Engines: Pinto and CVH fours, 2.0 DOHC, Cologne V6 (2.3, 2.8, 2.9), Cosworth YB 2.0 turbo, diesels
Built in: Genk (Belgium) and Dagenham (England), with assembly in several other countries; RS Cosworths were built at Genk, and the RS500s were then converted from three-door Cosworths by Aston Martin Tickford in England

Why people buy one

The RS Cosworth family is one of the defining Ford performance cars of the 1980s, built to homologate the Sierra for Group A touring car racing.
The XR4i and XR4x4 offer V6 performance and rear-wheel or four-wheel drive with simpler mechanicals than a Cosworth.
The Sapphire RS Cosworth saloon is a more discreet shape than the winged three-door, and the 4x4 version adds all-weather traction.
Ordinary Sierras share much with the performance cars, so mechanical parts knowledge and service experience are widespread.
Owners' clubs cater for both the XR and RS models, with registers and technical advice for checking identity.

What to weigh up

Copies, replicas and ringers of RS Cosworths and RS500s exist, and a car built up from an ordinary Sierra shell is not a genuine RS, whatever its badges say.
Many Cosworths were stolen and recovered, crashed or both in the 1990s, so a history check (an HPI-type check for outstanding finance, write-off and theft markers) is essential before bidding.
Most Cosworths have been modified for more power; non-standard chips, turbos and fuelling can shorten engine life and complicate originality.
Mid-1980s C and D registered Sierras are reported as the worst for rust, and British-built cars generally fared worse than Belgian-built ones.
Running costs of a YB turbo engine are high if it has been neglected, and some ABS and trim parts are increasingly hard to find.
The XR4i's plastic cladding and biplane rear spoiler divided opinion when new, and survivors are scarce.

Where they rust

Rear chassis rails, especially the box sections near the rear spring seats.
Inner and outer sills, including the jacking points.
Front suspension turrets, which can fail in severe cases; front-wheel camber that differs from side to side can be a clue.
Bulkhead, battery tray and inner wings in the engine bay.
Floorpan and front crossmember.
Boot floor and boot aperture, particularly around the rear bumper mounts.
Inner and outer wheelarches and A-pillars, where dirt collects.
Doors, front wings, bonnet and tailgate edges.
Sunroof surround on cars fitted with one.

Mechanical weak spots

Cosworth YB engine: listen for piston slap from cold and knocking when warm, and check for coolant loss or overheating that can point to head gasket failure. The cambelt is commonly changed every 30,000 miles or five years.
Turbo: blue or white smoke and play in the impeller shaft point to wear; split or loose boost hoses cause misfires and lost power.
Gearboxes: the two-wheel-drive Cosworths use a Borg Warner T5 that is notchy when cold, while the 4x4 uses the MT75. Crunching synchromesh and a noisy reverse are common faults.
Axle: listen for whining from the differential and rumbling from the rear wheel bearings; a worn or faulty limited-slip differential is also reported.
V6 cars: tappet noise, plastic timing gear on earlier engines and K-Jetronic fuelling problems on the 2.8 are known issues.
Suspension and steering: worn track control arm and trailing arm bushes, tired dampers, broken coil springs and a worn steering rack cause wandering.
Brakes: front calipers can seize and discs warp; ABS faults show as a warning lamp that stays on or a heavy pedal.
Electrics: ageing engine-bay wiring, cooling fans that fail to cut in and badly fitted alarms are common sources of trouble.

At a Mathewsons viewing

Compare the VIN on the V5C with the plate on the slam panel and the stamping under the carpet flap beside the driver's seat; on a three-door RS Cosworth or RS500 the VIN should begin WF0EXXGBBE. Walk away from ground-off, welded-over or re-stamped numbers.
On a claimed RS500, ask for documentation and ask the auction house or vendor for the engine number (it sits behind the cambelt cover), then check it and the VIN with the owners' club register.
Look for etched registration numbers on the glass and ask to see any history check, MOT history and previous V5C records; mismatched etching can indicate replaced glass or a past theft.
Lift the boot floor covering and front carpets, and use a torch along the sills, rear rails and under the front turrets for fresh underseal or new welding.
Open the bonnet and look at the bulkhead, battery tray and turret tops, and note non-standard parts such as aftermarket intercoolers, turbos, injectors or wiring; if staff start the car, listen for piston slap and watch for smoke.

Parts, specialists and clubs

Mechanical parts for most Sierras remain obtainable because the engines and gearboxes were shared with other Fords. Cosworth-specific trim, body kit panels and ABS components are harder to find, and the clubs can advise whether claimed Ford Motorsport parts are genuine. The owners' clubs are the best route to registers, technical help and identity advice.

Seen on Bangers & Cash

Ford Sierra Cosworth (Bangers & Cash series 1, episode 2, First shown April 2019)
Ford Sierra Cosworth (Bangers & Cash series 4, episode 5, First shown April 2021)
Ford Sierra Sapphire Cosworth 2WD (Bangers & Cash series 6, episode 9, First shown October 2022)
Ford Sierra Cosworth (Bangers & Cash series 8, episode 4, First shown September 2023)
Ford Sierra Sapphire 2000E (Bangers & Cash series 9, episode 1, First shown February 2024)
1987 Ford Sierra Cosworth (Bangers & Cash series 10, episode 11, First shown October 2024)
Ford Sierra XR4x4i (Bangers & Cash series 14, episode 7, First shown September 2026 on U&Yesterday)

Sources

Buyer's guide: Ford Sierra RS Cosworth (Classic & Sports Car), 5 April 2019
Sierra RS Cosworth buyer's guide (Fast Car), 26 August 2022
Ford Sierra buyer's guide (Classics World), 1 October 2025
About the RSOC (Ford RS Owners Club), accessed 13 October 2026
Ford Sierra (Wikipedia), accessed 13 October 2026

An independent guide from Thornton-le-Dale. Not connected with Mathewsons or the programme.