Mercedes SLK corrosion could be an issue, so be sure to check all the suspension arms as well as the static brake pipes for any signs of rust. If these items have corroded, then there`ll be much worse hiding away. Check the wheel arches and the sills, the boot lid and registration plate surrounding, that area also around the rear registration plate light and fuel cap flap too. Inspect the front leading edge of the bonnet; here the paint chips so the corrosion sets in. Take a closer look at the front end for any poorly touched up stone chips; you might be budgeting for a whole front end respray otherwise. The front wings are prone to rust; most likely up around the wheel arch lip, as well at the lower edge where it meets the wrap around bumper. End by checking where the two sections of the roof meet; this is a corrosion hot spot, it can be found on both parts.
The Mercedes SLK 4 cylinder engines are pretty robust but the supercharger bearings do fail, thus leading to a rattling on tick over. The supercharger will in fact continue to work, but will get noisier as time goes on. Reconditioned superchargers are around £500, a big expense if you`ve just purchased the car. The SLK V6 too is very tough, but suffers air mass sensor failures; new ones cost about £85.
Some Mercedes SLK cars do have a manual gearbox, but in most cases the UK SLKs have got a five speed auto gearbox that’s very lively and shifts gear ratios very smoothly. If the Mercedes SLK has a six speed manual gearbox, please make sure you check the changes are very slick; this gearbox can fail, but occurrences are quite rare. Manual gear boxed SLK`s have quite a following but most SLK buyers do prefer an auto; the Mercedes SLK32 AMG only came in auto form.
The Mercedes SLK charging system, like most cars can fail when a voltage regulator in the alternator packs in. The front fog lights can mist up and corrode the reflector internally, so again make sure there is no rust in evidence. The SLK headlights are very poor on the dipped beam, but fine on main beam. The best solution is in fact to fit more powerful aftermarket bulbs. Another likely electrical glitch is the heater fan resistor, although easily and quite cheaply replaced. The air conditioning condenser however and compressor, can cost over up to £1000 to replace The rear lights circuit boards can actually melt although repairable, and the security alarm horn can go off sounding continuously if water has worked into it. Many Mercedes SLK owners just disconnect it.
Another headache is catalytic converters, they can pack in, that`s why you should always get the emissions checked before buying a car, replacement converters are extremely costly. There are in fact three of them on the SLK so if they all needed to be replaced, the total bill could easily be over £1000.
The Mercedes SLK roof mechanism is quite complicated but it`s reliable. But, there are some sensors that can play up if the roof isn’t used quite regularly, so use the roof, operate it up and down quite a few times just to make sure everything`s well. The hydraulic roof oil should be replaced every 10 years, so check this has been done; it’s worth actually swapping the roof pump relay periodically, as do they fail. They’re only £12 and only take minutes to swap.
Check the seats for any signs of wear, look especially the driver seat bolsters. Check behind the seats for any signs of water getting in. the rubber seals for the rear quarter lights often fail, but because they`re costly they just get left to leak – which increases the bill, unfortunately. Door check straps also fail; good news is that new ones are not expensive.
The Mercedes SLK factory supplied wheels are probably tatty by now, corrosion and the peeling of lacquer is normal, getting them refurbished is easy enough though. Costs anywhere between £50 and £100 a wheel, depending what finish you`ll want. Be very wary of any aftermarket wheels, as they can be poorly made, and most don’t suit the Mercedes SLK`s understated looks.