It’s affordable, has high build quality, a superb reputation, strong performance and surprising practicality – it all makes a compelling case for buying an SL

When it comes to real-world affordable cars, few are better engineered than a Seventies or Eighties Mercedes. One of the best on offer was the R107 SL, which was produced at a time when build quality was king: engineers ruled, rather than bean counters. However, while everyone clamours for its predecessor (the ‘Pagoda-roofed’ W113), the second-generation SL offers everything the older car does – and much better value besides.

Although these cars were built up to a standard rather than down to a price, you don’t need the wealth of Bill Gates to buy or run one. Indeed, many of the mechanical components are surprisingly cheap as they’re shared with contemporary Mercedes saloons. Simple enough for home maintenance, there’s also a raft of specialists out there to help you keep your SL in fine fettle.



The second-generation SL (third if you count the 190SL and 300SL ‘Gullwing’) survived an incredible 18 years – it holds the record for being Mercedes’ longest running model. Despite being introduced at the start of the 1970s, the car still looked fresh the day the last example rolled off the production line in 1989. Few other designs could stand such a test of time. Even now the car looks great: classy and understated with no hint of ostentation.

So, with relatively low values, peerless build quality, a superb reputation, strong performance and surprising practicality, there must be a catch, surely? Well, no; even the smallest engine offers strong performance, there’s unrivalled parts support from the factory and the SL is fabulously discreet while timelessly stylish. This really could just be the best all-round convertible for the summer.

What to look out for
Bodywork
The SL may be beautifully engineered, but just like any other steel-bodied classic it’s prone to tinworm. Rust can cause some major headaches – especially in pre-1977 cars – that were poorly rustproofed. Cars built after 1976 benefited from improved rustproofing, while those made after 1980 featured wax injection of the various cavities. SLs produced from 1986 were also fitted with wheelarch liners and featured galvanised bodyshells, making them the most durable of the bunch – although they can still corrode.

If the car is as strong as the day it left the factory, there’ll be no trace of scuttle shake whatsoever, and if you’re careless enough to invert the car, the windscreen surround should be able to save your bacon – although it’s probably best that you don’t try out this latter ability on the test drive.
Start by checking the air intakes at the base of the windscreen, which can get clogged up and lead to corrosion of the bulkhead. Repairs are tricky, which is why some cars are bodged or just left. To do the work properly will easily cost £1000 – and that’s assuming you don’t find any other problems once the car’s been stripped. The usual giveaway is wet mats in the footwells so your best bet is to unscrew the heater blower’s plastic cover on the bulkhead, which should give you the best view of what’s going on.



Continue by looking at the wheelarches, door bottoms and windscreen surround, all of which can corrode. Of more concern, though – and more likely to be rusty – are the jacking points and sills. If the latter are badly corroded, the car’s structure can be compromised. On pre-1980 cars, be sure to inspect the sub-frame, which can rot badly. Replacements are available, but to have a specialist do all the necessary work could cost more than £2000.

You’ve got two choices when it comes to replacement panels: pattern items or replacement tin from Mercedes. The former might not fit very well, the latter are expensive. Front wings are bolted on while the rears are welded; pay close attention to the state of the bumpers as they’re complicated and expensive to repair.

All R107s came with a factory-supplied steel hard top, which should have a paint finish that’s well matched to the rest of the car. It may be that the car’s bodywork has faded slightly over time while the hard top hasn’t – or one may have been resprayed without reference to the other. Make sure the hard top is supplied and fit it to ensure the colour match is decent – also check that it hasn’t rusted or been bashed about while in storage – a caring owner will have invested in a stand for it, allowing it to be stood upright and out of the way. If it has rusted, the most likely place for corrosion is along the trailing and leading edges.

Also make sure the hard top’s brightwork hasn’t been damaged when it’s been fitted or removed – Mercedes chrome trim is notoriously expensive to replace. Finish by checking that the hard top is the one supplied with the car: remove the roof and you’ll be able to see the car’s chassis number stamped below the nearside window. A hard top may be incorrect or missing because the car has been stolen or crashed – or it may simply be that the hard top has been replaced at some point because of damage.

Engine and transmission
A variety of six and eight-cylinder engines were fitted to the SL over the years. They’re all incredibly strong and will notch up a quarter of a million miles between full rebuilds – as long as the oil is changed regularly (at least every 6000 miles, and preferably every 4000). Failure to renew the oil regularly will lead to worn camshafts and followers along with timing chains.

The valve stem seals tend not to be as durable as the rest of the engine, though – they typically need to be replaced every 75,000 miles or so. It’s not a big job, however, and you can expect to pay a specialist around £400 for it. If the work needs doing, expect to see some blue smoke on start up, but then a clean exhaust once the engine starts to warm up. If you’re considering a V8, at around the same time as the stem seals need renewing you can also expect to have to fit a new set of tappets, which will add another £600 to the bill.

The six-cylinder engines were all-alloy and, as a result, they can corrode internally if anti-freeze levels aren’t maintained. However, unlike many aluminium engines the SL’s six-pot isn’t as prone to corrosion – so it should only be affected if it’s suffered many years of neglect, in which case corrosion will be the least of your worries.

If you’re tempted by a six-cylinder SL in the hope of enjoying better fuel economy, you’ll be disappointed. Because the V8s don’t have to work as hard, they tend to offer the same sort of fuel consumption as the six-pots – although no SL is especially frugal. Other engine-related problems to look out for include a silted-up radiator, which can affect any model – expect to pay around £200 for a recore. Cars built between 1972 and late 1975 can also suffer from problems with the electronic fuel injection. The Bosch KA system used from October 1975 is more reliable and easier to work on.
Condensation in the distributor cap can lead to poor running of a 300SL – only an original equipment part should be fitted or trouble is virtually guaranteed. The problem is, a cap in a Mercedes box costs around £100, which is why some owners try to cut costs.

Some SLs were offered with a manual gearbox, but these transmissions are best avoided because they’re invariably less pleasant to use and you’ll find it much easier to sell on an automatic car as a result. However, the three-speed unit fitted to early cars isn’t great, but the four-speeder fitted to post-1980 SLs is much more efficient and transforms the car. Pick of the bunch, however, is the gearbox that arrived in 1986, which is switchable between sport and economy modes. It’s so good that even a 500SL can return 30mpg when touring – although in everyday use this is more likely to drop closer to 22mpg.



Gearboxes rarely give trouble, but because the 500SL’s has to transmit so much torque, a rebuild can be needed after around 150,000 miles – expect to pay around £1500 to have the work done. Pre-1975 cars can also be less than 100 per cent reliable because they feature a fluid flywheel transmission – later boxes had a torque converter instead. And it’s this fluid flywheel that can cause problems: if there’s any sign of problems, expect to pay £1500 for things to be put right.

The rest of the transmission is equally tough, although inter-galactic mileages will take their toll on the back axles and propshaft couplings. Once again, it’s the 500SL that’s most likely to suffer from problems because of the engine’s torque. Expect to pay around £1500 for the back axle to be rebuilt, while a fresh set of propshaft couplings will set you back around £350.

Running gear
The SL’s steering, brakes and suspension were as well engineered as the rest of the car, so even high-mileage examples needn’t be suffering from a stack of faults. With many of the components shared with contemporary saloons, most bits are easy to track down and a lot of the service items are very affordable too.

While components such as ball joints will often last the lifetime of the car, dampers go soft over time and this usually isn’t picked up on. That’s why it’s worth fitting a new set of dampers as a matter of course, unless you know it’s been done within the last few years – expect to pay around £1000 for a set of four.

All SLs came with power steering – there was a box rather than a rack. Once 80-90,000 miles have been racked up the box can show some wear but this can usually be adjusted out. However, there’s only so much adjustment possible, so if the car has done a massive mileage you may have to invest in a box rebuild, which can cost anything up to £1500.

It’s good news on the braking front too, as this is another well-engineered system that gives few problems. All cars came with a servo and discs all round, while many of the later cars also benefit from anti-lock technology. One thing that’s worth watching out for is pattern pads being fitted; they tend to rob the brakes of feel, which is why it’s worth fitting only the genuine article.

It’s a similar story with the alloy wheels, as Mercedes used forged parts rather than cast. As a result an SL’s wheels are surprisingly durable and unless they’ve been kerbed badly the worst thing you’re likely to have to watch out for is peeling lacquer. However, because the wheels are so well made, refurbishing them is very easy, and not especially costly.

Electrics and trim
Apart from some later SLs that were reasonably highly specified, most cars didn’t come with huge amounts of powered accessories. That’s not to say that fixing problems is straightforward though, because accessibility can be an issue, which makes pinpointing issues a pain.



Some later SLs came with refinements such as heated seats and air conditioning, while virtually all cars came with powered windows – some very early examples had winders, though. What you won’t find is a powered roof, as Mercedes never offered one. There was an aftermarket conversion offered for a while, however, by an outfit called Auto-top – you’re unlikely to find a car that’s fitted with one of these, though.

On the subject of hoods, you must raise and stow the roof a few times to make sure it’s not damaged and that it seals properly. Some cars never have their roof raised; the hard top either stays on all the time or the car just comes out of the garage when the sun is shining. As a result, the roof can shrink and simply won’t fit when it’s raised – and if you want a new one fitted, you shouldn’t expect to have any change from £600-£1200.

Some SLs came with cloth trim, some with leather, while many were supplied with an MB-Tex finish. This is Merc’s simulated leather that’s tough and easy to keep clean – it’s also hard to distinguish from genuine hide, so don’t feel short-changed if you have to settle for a car trimmed with this.

Worthwhile upgrades
The SL is one of those cars that doesn’t benefit from mechanical upgrades – it was so well engineered that improving on the standard product is very difficult. Indeed, be suspicious of cars that have been modified, as the suspension and braking systems are excellent in standard form and so are the engines and transmissions. Also be very wary of SLs with non-standard wheels and tyres, as these can easily upset the car’s dynamics.

However, audio and security upgrades can be incorporated, while wind deflectors are also very popular. Expect to pay around £200 for one from an outfit such as the SL Shop.

The same company can also supply rear seats for £299 in vinyl or £425 in leather, while rear seat belts can be offered too. Choose from a three-point set up for £200 or a four-point option for £400.