July 4, 2022

The unique Sierra RS Cosworth three-door is ultra-cool, immensely tuneable and intensely fascinating. Right here’s the best way to purchase a bank-beating funding that’s equally capable of annihilate your pockets… Sponsored by Adrian Flux.

Information from Quick Ford. Phrases: Dan Williamson 

Why you desire a Sierra RS Cosworth three-door…

  • Blimey. Who doesn’t desire a three-door Cosworth? It’s essentially the most iconic automotive of a technology, and even the title sends shivers down the backbone of any true petrolhead.
  • Though costs have rocketed in latest instances, Sierra Cosworth values will stay agency for a few years to return. So why not take pleasure in your funding – even when meaning parking it in your front room and gazing it.
  • It’s a murals you possibly can drive to the outlets. It is likely to be a homologation particular, nevertheless it’s nonetheless a five-seater hatchback with an enormous boot.

Why you don’t desire a Sierra Cosworth…

■ Cossies are now not supercars for the working man. Immediately you want a mortgage to purchase a three-door and balls the dimensions of melons to drive one because it’s meant.

■ So-called Cosworth Tax is actual: components costs are not any joke, with large payments for changing real Ford trim or fixing an inevitably smoky or rattly YB. And it’ll break down…

■ Massive cash chases factory-original Cossies, so many masquerading as unmodified vehicles led earlier lives as 500bhp hooligans.

Ford Sierra RS Cosworth three-door historical past

September 1982 – Ford Sierra launched in UK to interchange outdated Cortina; Sierra gross sales start throughout October 1982. Typical front-engine/rear-wheel-drive structure however patrons are unimpressed by the aerodynamic styling, supplied as three-door or five-door hatchback or property. No high-performance mannequin.

December 1982 – Sierra XR4i obtainable, that includes 150bhp 2.8-litre Cologne V6 engine, sports activities styling with double rear spoiler and strange three-door bodywork with break up rear aspect home windows.

March 1985 – Sierra RS Cosworth unveiled at Geneva Motor Present. Meeting of not less than ten pre-production vehicles takes place all year long. Motorsport homologation requires 5000 manufacturing vehicles for eligibility in Group A touring automotive racing.

February 1986 – Sierra RS Cosworth sequence manufacturing begins at Genk, Belgium alongside common Sierra fashions. Proper-hand-drive manufacturing vehicles start to depart the manufacturing unit from April. All use fundamental Sierra three-door bodyshell as an alternative of XR4i sort.

15 July 1986 – Sierra RS Cosworth formally launched in UK, powered by turbocharged 2.0-litre DOHC engine produced by Cosworth Engineering and detuned to 204bhp for highway use. Customary options embrace wind-tunnel-proven bodykit with giant rear wing, 15in cross-spoke alloy wheels, tinted glass, sunroof, electrical entrance home windows, central locking, Recaro entrance seats, three-spoke leather-based steering wheel, 170mph speedometer and turbo enhance gauge.

December 1986 – Sierra RS Cosworth manufacturing ends, after 5542 are constructed; 500 of these are transported to Tickford, UK to be transformed into RS500 evolution fashions.

Sierra RS Cosworth

Ford Sierra RS Cosworth purchaser’s information


Cosworths have been topped king of the Nineties’ car-theft pandemic, and even at this time it’s important to make sure any three-door hasn’t been stolen, written off or had its id modified. A historical past test is crucial, and if it doesn’t add up, steer nicely clear.

Evaluate the chassis quantity on the logbook with the quantity on the VIN plate riveted to the slam panel and beneath a flap within the carpet beside the motive force’s seat; it ought to learn WF0EXXGBBE, adopted by a sequence of two letters and 5 digits; these final seven characters ought to match the unique engine quantity. Watch out for lacking stamps, though a number of Sierras have been welded over attributable to rotten inside sills. Any ground-off or home-stamped quantity is a particular code that interprets as ‘run away.’


A YBB’s engine quantity is on a flat part close to the offside engine mount, with one other hand-stamped by Cosworth on the entrance of the block subsequent to the water pump, behind the cambelt cowl; it can start with YBB, adopted by a number of numbers.

Different digits on the VIN plate ought to learn N5 for engine, B (right-hand drive) for drive, J for trans, 3 for axle, S2 for trim, and BEF within the sort field.

Fakes, ringers and replicas are on the market, value significantly lower than real Cosworths. An actual UK three-door Cosworth highway automotive can have a factory-fitted sunroof, tinted glass (test for an etched registration quantity), electrical entrance home windows, larger gearbox tunnel (in contrast with a base-model three-door Sierra shell), straight (horizontal) towing eye, and factory-pressed cutout behind the ABS pump.

Sierra RS Cosworth


Cosworth YB powerplant is the stuff of legends. It’s additionally the creator of nightmares if issues go incorrect. They usually actually do.

Authentic three-doors had a YBB engine. Early variations have been weakest, however all ought to have been repaired or rebuilt by now. Hear for piston slap from chilly: if it nonetheless feels like a diesel when heat, account for a rebuild. Drained YBs are inclined to growl and knock, suggesting crankshaft/bearing/bore put on and large payments; all components can be found, nevertheless it’s an costly enterprise.

Head gasket failure might be equally wallet-worrying – particularly if it damages the cylinder head. Test for coolant dripping down the cylinder block on the exhaust aspect, water within the oil, or white clouds exiting the exhaust.

Black smoke is regular for a tuned engine (operating wealthy), however watch out for blue plumes of oil smoke: odd puffs at idle are widespread, however heavy smoke underneath throttle might be worn piston rings or a blown turbo; test it for play by eradicating the consumption hose and wiggling the compressor wheel.

Misfires are a well-known issue of Cosworth possession – typically critical (similar to a blown head gasket) however often symptomatic of an aged electrical or ignition system. Cossies are famend for consuming spark plugs, leads and coil, and lots of points are cured with a wasted spark conversion – however that detracts from originality and worth. Enhance issues could also be attributable to break up or free hoses, sensors and regulators. Swapping paper gaskets for Cometic sort is beneficial (particularly on the inlet manifold), whereas a substitute engine loom can work wonders.

Test the present wiring for corroded, chafed or bodged-together cables and connectors, particularly within the engine bay beneath the nearside bonnet vent. Be sure that the cooling followers reduce in when the engine’s scorching (the wiring is vulnerable to melting), and examine the gasoline pump, filter and cradle (beneath the boot ground). Take a look at the pump is receiving 13 volts, and if the cradle is caked in rust, anticipate issues.

Previous three-door ECUs (Degree 1/L1) may also be problematic, usually supplanted by a Sapphire’s L6. A cheeky Stage 1 chip wakes up a Cossie, and shouldn’t detract from the automotive’s worth.


Robust and a bit tractor-like, the rear-wheel-drive Cosworth’s BorgWarner T5 gearbox can take a great deal of energy (and abuse). However after 35 years, it’s honest to anticipate a three-door to not really feel contemporary.

The gearshift needs to be heavy however exact. If it resists and crunches when trying a change (particularly from third to second or third to fourth), suspect worn synchromesh rings; the one treatment is a gearbox rebuild. There’s no synchro on reverse, so it’s often noisy except you choose fifth earlier than transferring the gearstick.

Take a check drive to hear for nasty noises from the rear finish. Rumbling suggests knackered bearings, which can finally fail and lose drive. Whining will probably be from the differential – and it’s quite common for RWD Cosworths to have a duff LSD, spinning up one rear wheel. Some sounds are much less critical – similar to vibrations from worn bushes on the differential or propshaft.

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Clutch slip is widespread on Cosworths, particularly when modified. To test, ground the throttle in fifth at 3000rpm, and make sure the highway pace will increase in step with engine revs.

A heavy clutch pedal might be attributable to a sticky cable, which runs too near the exhaust downpipe and turns into stiff – though a high-power machine might be fitted with a paddle clutch. Hydraulic clutch conversions ease the pressure, however devalue an unique three-door.

Sierra RS Cosworth


Don’t anticipate fashionable ranges of dealing with or consolation, however any three-door ought to nonetheless really feel full of life and responsive.

Most have had their suspension upgraded over time, however many are drained by now. Worn bushes are the chief perpetrator. Wandering from the entrance is usually brought on by sloppy monitor management arm bushes (exchange with polyurethane), whereas vagueness on the again is probably as a result of trailing arm bushes. Sloppiness within the steering column bushes (low cost and easy to interchange) or rack may additionally to be guilty for nervous dealing with; jack up the entrance wheels to test for play, hear for a loud PAS pump and search for leaks.

Soggy springs and dampers result in boat-like physique roll; a tough and crashy experience might come from mismatched elements (or coilovers too exhausting for the highway), whereas damaged coil springs trigger clonking and vibrations – additionally signs of knackered engine mounts or wheel bearings.

Three-doors had four-pot entrance brake callipers as commonplace, however they’re vulnerable to seizing in opposition to the 283mm ventilated discs; the signs are heavy juddering or pulling to 1 aspect. Vibrations felt via the brake pedal and steering wheel are probably attributable to warped/contaminated entrance discs and/or pads – Cossies devour them fairly commonly – however might additionally come from damaged suspension elements.

Rear discs on a three-door weren’t ventilated (not like the Cosworth 4×4), and have a tendency to stay on the handbrake mechanism; jack up the rear and spin the wheels to test, and study the brake strains for leaks and corrosion.

ABS was commonplace – and glorious for 1986 – however might be troublesome at this time. Beware if it seems like there’s no servo help (a heavy pedal) or the ABS warning lamp on the dashboard stays on after start-up. The trigger might be soiled or damaged wheel sensors, pump failure,  damaged wiring, fluid stage sensors or blown fuses. Diagnostics is pricey, and most components are expensive.


Rust is a critical Sierra drawback, however by now most three-door Cossies have been restored or in want of little or no work. However don’t take it without any consideration; even a low-mileage or renovated automotive requires a radical inspection.

Work your means up from the underside, checking the floorpan and chassis rails (particularly the rear field sections close to the spring seats), inside and outer sills, entrance crossmember and boot ground, significantly across the bumper mounts.

Study the doorways, entrance wings and tailgate, together with the boot aperture (beneath the rubber seals) and A-pillars, plus the inside and outer wheelarches (the place muck gathers behind the plastic extensions and inside liners).

The Sierra’s engine bay is vulnerable to corrosion and stress fractures. Have a look at the bulkhead, battery tray and inside wings, paying shut consideration to the suspension turrets, that are recognized to fold inwards and collapse; one other warning signal is extreme destructive camber on the entrance wheels.

Test the headlamps for yellowed lenses, ensure the fog lamps and indicators aren’t cracked, and make sure the grille doesn’t have snapped lugs. Cosworth bumpers can sag, and have gotten more and more costly. Likewise, the long-lasting rear wing, which is vulnerable to snapping on its mounts. It’s widespread to seek out free trim after being eliminated for restoration, and even easy stuff might be loopy cash; lookup the price of aspect rubbing strips for instance.


If the Sierra continues to be on its unique cross-spoke alloys, test the lacquered diamond-cut end isn’t flaking, and make sure the centre caps nonetheless have their locks.

Accident harm may additionally be evident (large numbers of Cossies have been crashed), so examine the hidden areas beneath the boot mat and behind trim. Collectors wish to see unique/uncut panels (with date stamps on the entrance wing rails), manufacturing unit seam sealer and paintwork; all three colors are equal in worth.


A mint inside provides hundreds to a three-door’s worth – and a ropey cabin subtracts as a lot.

Dashboards are famend for warping and splitting, and good replacements price greater than £1000. Repairs are potential, though most don’t are inclined to final lengthy. Some vehicles have been fitted with uncracked Sapphire dashboards (which lack the speaker grille within the prime of the real three-door sprint), with applicable discount in worth.

Sierra door playing cards are equally uncommon and expensive, affected by the vinyl wrinkling up and peeling off, or being hacked to deal with audio system.

Manufacturing unit-fitted Recaro entrance seats have gotten exhausting to seek out in glorious situation, so – sure, you guessed it – they’re stupidly costly. Test for tatty bolsters, sagging fabric, and sloppy reclining mechanisms. Be sure that the motive force’s aspect hasn’t been swapped for a passenger seat, which has the recliner knob subsequent to the centre console as an alternative of the right place beside the door.

Sierra headlinings are vulnerable to sagging (and might be repaired comparatively cheaply), as are rear parcel cabinets (which price a bomb); a Cosworth ought to have a single-piece shelf with a plastic storage field (designed for a non-standard first assist package).

Don’t be shocked to seek out sticky electrical home windows or central locking motors, a non-working heater blower, or random bulbs alight on the dashboard-mounted graphic data show; most components are low cost sufficient to repair.

Use the cabin to evaluate the remainder of the automotive. Cosworth trim is comparatively hardy, so should you see a supposedly-low-mileage Sierra with tatty steering wheel and worn pedal rubbers, suspect it’s been across the clock.

Sierra RS Cosworth

Ford Sierra RS Cosworth three-door insurance coverage quote: Adrian Flux

Automotive: Ford Sierra RS Cosworth 3-door

Worth: £60,000

Driver and data: 28-year-old male, with a full NCB, dwelling within the TN14 put up code, with a clear licence. The automotive is parked on the drive every evening and has mild modifications together with wheels, suspension, exhaust and air filter.

Quote: £600 together with insurance coverage premium tax / £650 extra / Complete cowl

Tech Spec: Ford Sierra RS Cosworth three-door


1993cc four-cylinder, 16V, DOHC YBB with cast-iron ‘205’ block and alloy cylinder head, 8.0:1 compression ratio, toothed belt drive, Weber-Marelli multi-point gasoline injection and digital administration system, Garrett T03 turbocharger with intercooler


Rear-wheel drive with Borg Warner T5 five-speed handbook gearbox, viscous-coupling limited-slip differential, 204mm clutch. Remaining drive ratio: 3.65:1


Entrance: MacPherson struts, Fichtel & Sachs gas-filled dampers, coil springs, decrease monitor management arms, 28mm anti-roll bar; rear: semi-trailing arms, coil springs, Fichtel & Sachs gas-filled dampers, 14mm anti-roll bar


Entrance: 283mm ventilated discs and four-piston callipers; rear: 273mm strong discs and floating callipers; Teves ABS

Wheels & Tyres:

7x15in multi-spoke RS alloys and Dunlop D40 205/50VR15 tyres


Three-door Sierra hatchback physique with distinctive polycarbonate bodykit comprising deep entrance bumper, aspect skirts, wheelarch extensions and rear wing, rubber entrance decrease splitter, entrance fog lamps, mesh grille, bonnet vents, colour-coded electrical heated door mirrors, tinted glass, electrical entrance home windows, central locking, tilting/sliding glass sunroof (all UK highway vehicles). Colors: Diamond White, Black or Moonstone Blue


Recaro entrance seats with gray Roma fabric trim, leather-rimmed three-spoke steering wheel, leather-covered gearknob, enhance gauge inside instrument binnacle