Used car buying guide: Mini Cooper S

Mini Cooper S

Did you know? The convertible could be optioned with a so-called ‘Openometer’…

Second generation BMW Mini Cooper S is a riot to drive and more affordable than ever, but not without its issues…

The Mini is such a friendly little thing that it comes as a shock to discover that the minute your back is turned, the Cooper S of 2007-13 likes to throw its timing chain.

It’ll give you a few hints first, like a brushing noise or perhaps a rattle, from cold at idle. I once owned a Vauxhall Zafira 2.2 that did the same thing. The noise came and went and then one day the pistons and valves shook hands, and that was that.

The same will happen to the Cooper S’s engine, although more likely to any fitted before 2011, after which a revised chain tensioner was installed.

That’s right: it’s the hydraulic tensioner rather than the chain that’s the culprit. It doesn’t help that the engine likes a drink – as much as a litre of oil every 1000 miles. That’s a healthy engine, by the way. As the cars get older, experts say the engines are springing oil leaks in most un-BMW-like ways. Fail to keep your eye on the level and a red warning light will be the least of your worries.

Find a used Mini Cooper S on PistonHeads

The second-generation R56 Cooper S was launched in the shadow of its predecessor, the popular R53 of 2002-06. That earlier version was powered by a Chrysler/Rover-developed supercharged 1.6-litre engine made by Tritec. Its successor dispensed with that in favour of the new BMW/Peugeot-developed Prince engine, a turbocharged 1.6 making 173bhp, with 177lb ft from 1600-5000rpm or an overboosted 192lb ft.

Its codename is N14 and it has BMW’s infinitely variable single Vanos valve timing. This is important because, in early 2010, as a result of what at the time BMW doubtless referred to as ‘continuous product improvement’ but what you and I might call a barrage of complaints, it replaced it with a revised version called the N18.

Happily, the uprated engine produced 182bhp and, among other things, had a double Vanos system controlling both intake and exhaust valves to provide a more even spread of torque and lower emissions.

But it also gained mods that looked suspiciously like a ‘fix’ to an unacknowledged problem. Changes included redesigned pistons, an uprated boost line to the turbo, improved crankcase ventilation, a heat shield over the turbo oil pipe and a rigid instead of flexible turbo intake pipe. Experts reckon the N18 is the engine to have. You can identify it by its large plastic cover, while the N14 is ‘naked’. Meanwhile, onthe transmission front, the manual gearbox gained an improved clutch for better gear synchronisation.

Bizarrely, the changes were followed a few months later by a full facelift (new bumpers, revised interior, LED tail-lights with pulsating brake lights to indicate the force being applied and additional air intakes). As already noted, in 2011 a revised timing chain tensioner was fitted. Now, at last, the R56 couldn’t spring any more surprises except the one common to any well-bought R56 Cooper S, and that’s just how much fun it is to drive.

How to get one in your garage: 

An expert’s view, Alex Castle, MASTERDRIVER.CO.UK: “The R56 timing chain can let go at around 80,000 miles. The plastic tensioner guide is the culprit. If you hear a brushing sound, it’s on the way out and you should change it without delay. The later N18 engine is much improved but the tensioner wasn’t upgraded until 2011. Fortunately, owners are enthusiastic and look after their cars. There are plenty to choose from so you can afford to be fussy. New, options were pricey, but that cost evaporates as the cars get older so fully loaded Coopers aren’t much more expensive. My favourite extras are the panoramic roof and Harman Kardon sound system.”

Buyer beware…

TIMING CHAIN – The timing chain, or more specifically the tensioner, is the weak spot. Keeping the oil topped up is vital but ultimately poor design is to blame. A rattle and brushing noises at idle from cold is the tensioner’s ‘death rattle’.

OIL LEAKS AND MISFIRES – Oil leaks are becoming an issue on older cars. Check the rocker cover, crank seals, sump, turbo oil feed, front and rear main bearing seals, solenoids and cylinder heads for drips. Valve stem seals are starting to fail on older cars. Permanently low oil allows sludge to build up in the Vanos valve control system, affecting performance. Hesitation, uneven idling and misfiring could be carbon build-up on inlet valves or failing coil packs.

COOLANT SYSTEM – Look for cracks on the plastic coolant thermostat housing. Check if the water pump has been changed; it’s best done at around 50,000 miles. Check the plastic lower radiator support – it’s prone to kerb damage.

TRANSMISSION – Check the clutch operation – failure as early as 20,000 miles isn’t uncommon. Worn synchros are rare so graunching suggests seriously hard use. Feel for a harsh shift on autos, often caused by a faulty valve body which could require a rebuild or replacement of the gearbox.

SUSPENSION AND BRAKES – Check the front wishbone bushes, which have to work hard. The anti-roll bar bushes have an easier time.

Also worth knowing:

Earliest R56s are 12 years old and the suspension, while sophisticated, isn’t the most adept and will probably be in need of a refresh. For less than £1000, you can replace wishbone bushes, springs and dampers with upgraded polyurethane bushes, Koni shocks and Eibach springs.

How much to spend:

£2300-£3495 – Launch cars with around 100k miles, generally good histories and in serviceable condition.

£3500-£4995 – Lots more lower-mileage 07 cars (circa 75k miles), with more lower-mileage 08s and 09s towards £4995.

£5000-£6995 – Very low-mileage 07s but many more 08 to uprated 10-plate cars with decent mileages.

£7000-£8995 – A good choice of proper 10 to 13-plate cars.

£9000-£10,500 – Plenty of low-mileage 11 to 13-plate cars here, the most expensive being a 2012 with 19k miles and £5000 of extras including powered panoramic sunroof.

One we found:

MINI COOPER S, 2010/10, 45K MILES, £6900 – Not only has this got the uprated N18 engine but it’s also the later facelift car with revised interior, fresh bumpers and LED tail-lights. Has full Mini history and eye-popping red leather too.

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Source: Autocar Online

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