Ford Sierra RS Cosworth (1985 – 1992) Review

Ford Sierra RS Cosworth (1985 – 1992) At A Glance


+Amazing to drive, easy to tune, bulletproof engine

-Cheap interior, avoid tuned cars, more than a few fakes out there

If you thought the extrovertly bespoilered Sierra XR4i wasn’t quite enough, your prayers were answered in 1985, when Ford unveiled its latest homologation special, the Sierra RS Cosworth. It was powered by a 1993cc double-overhead camshaft engine breathed on by Cosworth, with a Garrett turbocharger upping the power to an Integrale and quattro-rivalling 204bhp.

Just 5545 of these original two-wheel drive whale tail Cosworths were built, and insurance premiums were astronomical, as they weren't exactly difficult to steal, Chubb locks or not. It didn’t help, of course, that a Cosworth Sierra was very obvious even from long distance, with possibly he least subtle bodykit this side of a Countach.

In 1987, Ford launched the RS500. Ford chose the name to indicate that only 500 of this 1987 evolution of the original RS Cosworth would be built. It was constructed for motor sport homologation purposes, and was put together by Aston Martin's subsidiary Tickford. Mechanical modifications and a bigger turbo increased power to 224bhp. As well as uprated brakes and a modified front end, the RS500 signified the zenith of Ford’s spoiler obsession (on the Cosworth), with a second small one now hiding beneath the existing whale-tail contrivance at the rear.

When the Sapphire Cosworth was launched in 1988, it marked the beginning of a quieter era for Ford's homologation special. It was much more discreet and down-to-earth than previous Sierra Cosworths, although there were plenty of signs - such as special alloy wheels - to give the game away. As its name suggests, it was based on the Sapphire saloon version of the Sierra and used the existing 1993cc Cosworth twin-cam turbo. Even the two available colours were sensible too; white or grey.

All that still didn't manage to erase the car's image for being a joy-rider's dream - and they continued to be stolen in huge numbers. Which left insurers with little choice than to fully load premiums. The Sierra's image in the UK was ruined, although if you look closely at its replacement - the Escort RS Cosworth - you'll see it's pretty much identical under the skin.

In 1990, the RS Cosworth received four-wheel drive, creating the best version of the lot.

Ask Honest John

What steps do I need to take in recommissioning a car that's been standing for 18 years?

"A friend has asked by advice on returning their 1992 Sierra Sapphire Cosworth 4WD back to roadworthy condition. It is in immaculate original condition but has spent the last 18 years standing in a garage. Other than doing the obvious things like fitting new tyres, battery, filters and changing fluids, would it require specialist attention? I'm reluctant to even try cranking the engine over for fear of causing damage, due to the possibility of internal corrosion and moving parts being 'gummed' up due to the oil not being circulated for so long."
You're absolutely right to be cautious. Just to get the engine going alone you'll want to do it by hand - and before you do that you'll need to take the spark plugs out and lubricate the cylinder bores. Too much friction at this point and you'll snap the piston rings. If it's stuck solid, try filling the bores with a cleaning solution (or a cola-based fizzy drink) and leave it overnight before applying more oil and trying again. If it does turn over easily by hand (ie with a socket on the crankshaft) then you can replace the fluid and filters and try to turn it over with fresh fuel and a battery. If you do decide to bring it fully back to life, you'll have to clean/replace the fuel lines, check the fuel tank isn't corroded, make sure all the electrics work such as the fuel pump, and get the brakes going again. If it's immaculate, it's a project well worth embarking on.
Answered by Keith Moody

How do I get my Sierra RS500 build number?

"How do I get my Ford Sierra RS500 build number?"
Speak to Paul Linfoot, he is the RS Owners' Club RS500 registrar. You can reach him via:
Answered by Keith Moody

What do you think is the best classic car to buy for £100K?

"What do you think is the best classic car to buy for £100K? Which would be fun and not too expensive to keep and might increase in value?"
Whatever classic you buy, you'll need to budget for maintenance and running costs, but really the best classic depends on what you want to do with it. Fancy something for solely for investment purposes? Ferraris and Porsches are often solid bets - think Testarossa or 911 Turbo. A high days and holidays car to enjoy with your significant other might be a W113 era Mercedes SL or a Jaguar E-type. If on-track action is your thing, you may be able to get a race car with FIA Papers - there are a few race-specific auctions to keep an eye on. Alternatively, an iconic piece of American muscle car action is well within your budget (think 1969 Shelby GT350 Mustang). Prefer your classics older? Then a Lagonda 2-Litre could be a smart buy. Stately and smart? 1950s Bentley S1 Continental. Modern high-performance? Ford Sierra RS500. Just make sure that whatever you buy you do your homework... and enjoy it.
Answered by Keith Moody

Do you know where I can get an air filter for my 1986 Ford Sierra Cosworth?

"Do you know where I can get an air filter for my 1986 Ford Sierra Cosworth? Ford don't list this item and I've tried Euro Car Parts, Car Parts 4 Less, etc."
This is one of those items that is harder to find stock than it is modified. Tracking down a new old stock air filter will have you hunting around autojumbles and contacting spares departments at clubs and ringing around Ford dealers. Alternatively, you could track down a performance item from a supplier such as K&N quite quickly. It just depends whether you want to keep the car original or not.
Answered by Keith Moody
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