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Ford Sierra Cosworth

Ford Sierra Cosworth Published: 10th Aug 2016 - 0 Comments - Be the first, contribute now!

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Last of the rear-wheel drive classic RS Fords and one of the best. Rough and ready but so exciting and also good value but there are many poor cars out there

If motorsport improves the breed, welcome to one of the best and most highly developed road cars ever made. Indeed, whether or not you believe the motorsport maxim, this truly is one of the all-time great road racers, just as happy to blitz the Nurburgring as to cruise the high street yet as easy to run as an Escort. When it comes to vers atility, few cars can match the be-winged Sierra.

The Cossie Jellymould came about because Ford had to produce 5000 roadgoing examples of its Group A-homologated Touring Car; when unveiled in 1985, every superlative under the sun was thrown at it. Here was a genuine 15 0mph car that was cheap, practical, easy to maintain with it and capable of being tuned to give ridiculous amounts of power. The motoring world would never be the same again. The three-door Cosworth Sierra’s lifespan was brief but glorious; by the time production was wound up in December 1987, more than 6000 examples had been built. However, that wasn’t the end of the line, because in 1988 Ford introduced the plusher less extreme S apphire R S Cosworth saloon in rear-wheel drive form. That survived for just a year, but by 1990 there was a fourwheel drive edition available with production lasting just two years before the Sierra-based R S Escort took over.

While the focus here is on the threedoor cars, most of the mechanicals are the same for the Sapphires too


1983 Ford gives the green light to a Sierra Group A race programme. Later that year, Ford’s Special Vehicle Engineering division is commissioned to produce a Sierra homologation special. Also this year, the hot Sierra 2.8 V6 XR4i is lauched complete with a special threedoor and a bi-winged rear spoiler.

1984 The first Cosworth Sierra prototypes are running and by March 1985 the car is ready for its unveiling at the Geneva show. It would be the end of the year before the press would get their first chance to drive the Sierra RS Cosworth though, with the car not going on sale until July 1986. When it did it was priced at £15,950, which was ludicrously cheap for a large family car capable of 150mph and 0-62mph in just 6.8 secs.

Power came from a turbocharged 2.0-litre D OHC engine with Marelli electronic fuel injection rated at 201bhp and 204lb/ft. A Borg Warner close-ratio five-speed manual gearbox allied to a limited-slip diff was the deal together with electronic anti-lock brakes but no traction control.

1987 If the st andard Sierra Cosworth was rapid, the evolutionary RS500 of 1987 was even more so. Hand-built by Tickford, just 5 00 examples were made. With its larger turbocharger and intercooler, twin injectors per cylinder, pressurised oil cooling for each piston and larger capacity oil and water pumps, power soared to 224bhp – raising the top speed to 153mph in the process. There are also larger ducts in the front bumper, to feed air to the brakes and intercooler, while aerodynamics are sharpened up courtesy of a front splitter and extra spoiler on the tailgate. The price was set at £19,950 and most cars came painted black, but white and metallic blue were available to special order.

1987 (2) Ford had to build 5000 examples of the Sierra RS Cosworth to meet Group A homologation rules. In the end 6 021 would roll off the production lines along with the 5 00 examples of the RS500. Next came the Sierra S apphire RS Cosworth which would be a regular production car. Less of an extrovert road racer, it’s the most civilised Cosworth. Priced at £19,500 and no cheaper than the RS500 but the latter model is now worth up to 10 times more. These Sapphires are rearwheel drive with the same 201bhp as per the original three-door car; 11,000 are made so there’s plenty remaining.

1990 The final fling for the sensational Sierra is launched – the Sierra Sapphire R S Cosworth 4x4. The most usable variation on the theme, the £24,995 price tag bought a quicker 217bhp version of the DOHC fourcylinder engine. By the time the model goes out of production in 1992, 9250 ex amples are produced.


When it was launched, everybody who reviewed the be-winged Sierra was blown away by its performance and tractability. Nowadays, 200bhp is no big deal – many small family hatchbacks can boast half as much again from powerplants no bigger than the hot Ford’s. But 30 years ago the Cossie changed everything and the reviews reflected that.

When Eric Dymock first drove the Sierra RS Cosworth for Fast Lane he enthused: “Even in relatively modest road tune, it is no fire-breathing, raucous and thirsty half-racing car. It is a tractable, relatively quiet executive saloon that idles evenly and smoothly in traffic, and only lives up to its dramatic appearance when the driver wants it to”. The same magazine ran a Cossie on its long-term test fleet, alongside a Sierra XR4x4 and a Sierra 2.0iS. After many months and thousands of miles the verdict came: “The Sierra Cosworth is no slick upmarket executive, nor a Japanese pseudo-sports car which cossets its passengers with tawdry opulence. It is quite simply the ultimate practical good-time car available today.

Its Siamese relationship with pukka saloon car racing means it steers like no other Sierra (and like few other road cars) with a response so quick and shockingly faithful it rewards the experienced driver with the treasures of uncompromised precision and accuracy. The result on the road is a Sierra that feels like a real racer… it makes a so-called sports saloon like the BMW 535i feel like a wet sponge”.

Other plaudits included, “The most exciting road car Ford has produced since the GT40,” from the Sunday Express and “The best road car Ford has ever built,” care of Car magazine

Without doubt, the original three-door the most thrilling and testing to drive (witness most of Ford’s press fleet was quickly wiped out by ‘skilled’ road testers) with the 4x4 the most usable as well as the cheapest. Rapid if rather rough and ready, the Cosworth engine is a bit loutish but that’s all part of the attraction.

Early models were a handful (no traction control remember!) but the saloons, and in particular, the 4x4, are much more manageable.

All are classic old school performance saloons the likes of which we’ll never see again. That was something that renowned road tester Roger Bell eluded to back in 1998 when evaluating the 2WD Sapphire. “If you like your gemstones roughly cut, coarse edge around a dazzling heart this Sapphire is a cracking car,” adding, “We shall remember these Cosworth flyers with affection, even awe”.


It’s no secret that Sierra Cosworth values have gone crazy over the last couple of years but there are still some bargains to be had – as long as you settle for a fourdoor car. Paul Linfoot is the senior registrar for the RS Owners’ Club and he also runs North Yorkshire RS Spares, which restores three-door Sierra RS Cosworths, focusing mainly on the iconic RS500.

Says Paul: “The Sapphires are picking up now, largely because the three-door cars have got so expensive. The rearwheel drive cars are more valuable than the four-wheel drive editions, probably because they’re earlier; in the classic world, later usually equates to less collectable. The best rear-wheel drive saloons are now touching £20,000, while £12,000-£15,000 buys something really nice. Cars with four-wheel drive aren’t far behind, but if you’re on a budget you should get more for your money if you buy one of these later editions”.

The three-door cars fetch a lot more money. Projects are few and far between, but if you stumble across a barn find that’s complete but needs recommissioning you’ll pay £7000- £10,000 for it. Something roadworthy but not special will fetch £15,000 while something nice is at least £20,000 – although if it’s a low-mileage example this will rise to £25,000. The best three-door Cossies are £35,000, but to command this they have to be low-mileage with few owners and in mint original condition.

While these prices may seem steep, they’re nothing compared with what you’ll pay for an RS500. If you can find a project you’ll pay anywhere between £15,000 and £20,000 for it while average cars are £35,000-£40,000.

A nice RS500 is worth £50,000 easily but if it’s a low-mileage car this quickly becomes £60,000-£65,000. If you want a super, original, low-mileage car that’s had few owners you can pay up to £100,000 for it – and according to Paul Linfoot that’s likely to go up even further.

Paul comments: “As with any classic car it’s the low-mileage, mint originals that everybody wants but there aren’t enough of them to go round. A lot of people fuelling the market either owned one years ago and are buying again for nostalgia reasons or they wanted one back then but couldn’t afford one.

“Most people are now buying these cars as an investment but a significant proportion – maybe one in four – buys their car to use it. Colour used to matter but not any more – buyers will settle for whatever they can find as long as it’s in superb original condition”.


There was a time when nobody kept their Sierra Cosworth standard but those days are now gone – originality is key. Says Paul Linfoot: “Even those who buy their Sierras to use keep an eye on the rising values and they don’t want to do anything that will devalue their car. As a result, just about modifications are out, with the exception of two – the suspension and exhaust. Even these will devalue a Cosworth slightly but they can both be reversed – not that the original parts are available to do so.

“Most of these cars have got tired suspension by now which is why many owners fit a Koni set-up, but painted black instead of the standard yellow, so it looks like the original. Doing this costs about £500 plus four hours to fit everything. The original exhaust is now unavailable in mild steel so owners generally fit a stainless steel system which costs £500- £600. In some cases, if a car still has its original mild steel exhaust in good condition, owners will remove it and store it to maintain its condition, fitting a stainless system to use the car”.

What To Look For



  • While corrosion is something you need to be on your guard for, it’s crash damage that’s killed most Cosworths. A lot of power and rear-wheel drive can be great fun if you know what you’re doing; many Sierras were driven (often illegally) by those who didn’t have the necessary skills.

  • An HPI history check is essential (01722 422 422,, and so is a thorough inspection of the car’s structure and panels. If there’s any hint of missing seam sealer or ripples in the inner wings, be very wary.

  • Serious corrosion anywhere points to poor crash repairs. However, minor rust is quite possible in a few isolated areas; it shouldn’t have spread though. The key areas include the joint where the front wings meet the slam panel, plus underneath the rubber trim inside the tailgate. Also, don’t overlook the metal behind the windscreen washer bottle, in the engine bay.

  • The boot floor can also corrode, as well as the doubleskinned rear chassis rails; the latter can be very awkward to fix, while inspections are tricky because the affected area is hidden by the beam axle. It’s the same with the inner wings and suspension turrets; don’t underestimate the cost and difficulty of repairing these areas correctly. However, at least the sills are easy to repair if rusty, as they’re single-skinned.



    • Despite the power the five-speed manual gearbox has to transmit, the Sierra’s transmission is durable, although you should expect crunching when selecting reverse as there’s no synchro. Even in perfect condition the changes are notchy; the first sign of trouble is baulking when changing up from third to fourth, as the synchro rings start to fail. It’s possible to live with that for a while, but when third gear breaks altogether you’ll have to get your wallet out. Rebuilding the gearbox costs £600-£1000; if the car has been caned constantly, the diff may also be on its way out. These aren’t weak as such, but will take only so much abuse before failing; rebuilt units cost £700 while used items are £400.

    • Clutches will last 40,000 miles even with some occasional abuse, as long as they don’t have to transmit any more than 330bhp. Replacements are easy to fit, and cheap too at £200-£250; more problematic is a worn propshaft centre bearing. These are unavailable new, so if there’s a vibration that you can drive through, expect to pay £70 for a second-hand propshaft soon.

    • Feel for play in the steering, as there’s a rubber bush in the universal joint that connects the rack to the column. The bush gets cooked by heat from the turbo, and once it’s gone you’re stuck because it’s an MoT failure point and new replacements aren’t available. If you’re lucky you’ll chance upon a used one for £100- £150, but don’t count on it.

    • Odd but not unknown, don’t be surprised if you find a 4x4 model with the AWD deleted; it’s done by owners who rear-wheel drive thrills. So check…

    • Like most Fords with track control arms, the bushes contained within aren’t up to the job. They wear quickly, so it’s best to fit polyurethane items at £150 for the whole set, including the anti-roll bar mounts. If the bushes have worn out there’ll be vibration under braking and the steering will be vague.

    • Few Cosworths are still on their original suspension; these cars were usually driven hard and fresh dampers would soon be needed. First make sure thats what fitted isn’t tired (doing a bounce test on each corner is essential), and also check that any aftermarket parts aren’t mismatched to produce weird handling characteristics. Other than this, there are no likely problems.

    • Most Cosworths have aftermarket wheels fitted, which is fine if they fit properly. Check there’s enough inner wheelarch clearance and ensure there’s no uneven tyre wear. The wheels are often upgraded to allow stronger brakes to be fitted; the standard system is good, but it’ll only take so much abuse before giving up. Whatever system is fitted, feel for juddering through the pedal (signifying warped discs); fresh discs cost £120 per pair. Many owners upgrade to an AP or Brembo 330mm set up, at £1500-£2000.

    • It’s also worth checking the brake pressureapportioning valve, which is fitted just ahead of the nearside rear wheel. They’re prone to leaks, and as the part is no longer listed, it can be a problem because it’s an MoT failure point. They’re hard to find used; if you can find one it’ll be £100-£150.




    • Cosworth was charged with delivering 100bhp per litre from the 2-litre Pinto four-pot; in the event it was tricky keeping it down to that. As such, the 2-litre twin-cam unit is unstressed when standard, but most cars have been uprated. As long as things have been kept sensible, there’s nothing to worry about; realistically the safe limit is 330bhp. The danger stems from early tuning ideas which (by way of chipping) simply poured more fuel. It worked, but also diluted the oil leading to premature bore and turbo wear.

    • RS500s have a much stronger cylinder block casting, capable of taking immense pressures before failing. However, cars that have been tuned to give much more than 430bhp will probably suffer reliability issues; if the engine isn’t standard, establish who has done the work.

    • Even standard powerplants suffer head gasket problems because of corrosion. If the engine runs hot and loses water for no apparent reason, the head gasket has blown. Unusually, a blown gasket with this engine doesn’t lead to mayonnaise on the oil filler cap, but it will pressurise the cooling system.

    • To check for this, remove the header tank cap when the engine is up to temperature; major bubbling means trouble ahead. The gasket’s weakest spot is at the back of the block, on the offside; once it has blown, your best bet is to fit an upgraded gasket that won’t breach so easily. A £105 Group A item is best; a specialist will charge £350 to fit it. A mod worth considering while you’re at it, is to convert the block from simple bolts to a more robust stud and bolt affair.

    • If there’s mayonnaise on the oil filler cap, it’s because the cylinder block or head has cracked – which means you’ll need to source a used engine to slot in. Bank on paying £2500-£3000 for a serviceable unit, or £7000-£8000 for an RS500 item.

    • If there’s lots of blue smoke coming from the exhaust, the bottom end may be worn, particularly if it’s a high miler; a full rebuild is £2000-£3000 if done properly. Blue smoke can also mean the turbo is on its way out, but this can also lead to white smoke from the exhaust; if in doubt, get a specialist to take a look. If the turbo does need renewing, a used unit is £250, a recon £600, while new ones are £1500.

    • Piston slap is common, because of the gudgeon pin’s poor design – there’s nothing to worry about as long as the noise disappears once the engine is warmed up. If there’s misfiring it’s probably because the phase sensor in the distributor is starting to break down. It’s easy enough to fix though; a new sensor can be screwed in quickly, with the part costing just £35.

    • Any car that’s been tuned will need servicing more frequently; if you’re looking at one that’s been upgraded significantly, check there’s a stack of service history with it – especially plenty of oil changes. Oil should be changed at least every 3000 miles, using a fully synthetic lubricant.

    • Note cam cover colours – it’s not purely cosmetic because some signified whether they are higherpowered or come with a cat. Seek advice from club.




    • There’s a VIN plate riveted to the slam panel, while the chassis number is also stamped into the floorpan, underneath a flap in the carpet between the driver’s seat and sill. The chassis and engine numbers should match on a Cosworth, but not on RS500s. These got a replacement engine in the Tickford factory but the registration document wasn’t updated to reflect this. If buying one of these later cars, contact the RS Owners’ Club to ensure the car has its original engine; replacement powerplants will reduce an RS500’s value significantly.

    • Many original trim parts have been obsolete for years and aftermarket bits are rife. The key part is the dash top, which splits in the sunlight. Cracks spread out from the central speaker, and while some repairs can be quite effective, the best solution is to fit a new panel – but they’re unavailable and good used ones can sell for £2000.

    • Door trims and seats need close inspection; the former often have speaker holes cut in while the latter wear all too readily. Parcel shelves also change hands for up to £1000 because there are so few to go round; many surviving units have huge holes cut in them for speakers.

    • If the car is unmolested you’ve got little to worry about; you need to start getting worried when there’s evidence of massive sound systems and poorly fitted aftermarket security systems. Although the Sierra’s electrical system isn’t especially advanced, havoc can be caused by components being poorly spliced into the loom.

    • Warning lights on the dash are common, often because the wiring has been messed with or there’s a faulty sensor somewhere. The ABS light is the most common troublemaker here, but don’t overlook the fact the warning light might not be telling porkies.

    • The fusebox may have melted, as the twin cooling fans take up to 30 amps, but there was originally only a 20-amp fuse fitted. It’s worth upgrading the wiring.

    Three Of A Kind

    BMW M5 (E34)
    BMW M5 (E34)
    When new the M5 would have cost rather more than the Ford; now the tables have been turned, with good cars available from £12,000. The last of the hand-built M5s, the E34 was also the last M5 to feature a six-cylinder engine. The ones to go for are the 3.8-litre models (earlier ones were 3.5) – ideally with the six-speed gearbox. You’ll have to search hard to find a good E34 M5 of any kind though.
    An evolution of the Delta HF Turbo, which was front then four-wheel drive, all Integrales had power going to each corner. Early editions had eight valves but from 1989 there were 16 valves; all Integrales featured a turbocharged four-cylinder engine and left-hand drive. Pick of the bunch is the Evo 2 of 1993, but they’re big money, so an Evo 1 is a good substitute.
    Another rally weapon for the road, the Impreza Turbo’s abilities are nothing short of breathtaking; a hard drive in one of these can change your perspective on performance cars. Buy an estate edition and there’s decent practicality, while upgrades for all cars are easy to find and fit. Amazingly low values mean many are bought by youngsters who abuse them, so close checks are essential by us oldies but they are tough.


    The Eighties are coming back into fashion in a big way, and cars like the Cosworth are seriously in demand. The thing is, buyers want a healthy dose of originality; wheels, seats and bodywork need to be close to ex-factory specification. With so many cars upgraded quickly after they left the showroom, many original parts have disappeared; any car that’s ex-factory will always be highly saleable.

    The Cosworth’s value and desirability has led to plenty of fakes being sold as the real thing. All genuine cars will have a factory-fitted tilt/slide sunroof; if you’re at all suspicious either walk away or get advice from the RS Owners’ Club.

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