Mercedes-Benz SLK-Class (1996 – 2004) Review

Mercedes-Benz SLK-Class (1996 – 2004) At A Glance

Excellent build quality, terrific engineering and a very good crash test rating. Much better drive from 2000 onwards.

Unrewarding steering, offset driving position and some problems with the 5-speed autobox.

Ask Honest John

I have an old classic. How's best to sell it?

"I have a 1998 Mercedes SLK with 97,000 miles. It's MOT'd until August but has a dodgy sunroof that we no longer need. Could you advise on how best to sell it? Should I get the roof fixed and tart up the paintwork? The interior is okay but scuffed and marked as you would expect. Is eBay sensible or is there a better option? Any advice would be gratefully received."

It depends on how much hassle you want. If you want a quick sale, we'd recommend sticking on eBay (perhaps as an auction) with an honest description and some detailed pictures. It'll achieve a fair price and hopefully won't be a long process. Alternatively, if you fix the roof and tidy up the paintwork, you could try advertising it on sites like Car and Classic for strong money. Also, look at some of the new classic car auction sites like Collecting Cars and The Market – cars like yours seem to make fairly high values on those. Or you could try a physical auction like Anglia Car Auctions.

Answered by Andrew Brady

Why won't my SLK unlock?

"My Mercedes SLK 250 won't unlock. Last Sunday it sat on my drive during very heavy rain and hasn't let anyone in since. The key raises the button but the car remains locked. Both keys have been tested. I've tried various tips from local experts and everyone is baffled (eg giving it five secs plus with the key held close to the handle to send an infra red signal). A mechanic jacked the front up and declared there was life in the battery. I'm about to get it spec lifted to the main Merc deal which my brilliant local garage said was probably best in case they failed to solve the problem. I reckon its to do with water ingress. This might be irrelevant but a few times the aircon hasn't switched on which I also think is after heavy rain. It makes me wonder if some filter is sodden or unseen gutter blocked and could this now be causing the car to lock down? "

This is a fairly common problem, unfortunately. We spoke to Mercedes specialist the SL shop, who suggested it may be caused by plenum blocked drains that allow excess water into the car via the heater motor chamber. 'Because the electrical connectors and ecu's are below the carpets they are often damaged. The quick check is to get a bucket of water and pour it onto the windscreen and make sure it flows out straightaway underneath the car on both sides. The drains usually exit behind the wheel arch liner.'

Answered by Keith Moody

What future classic should I buy for £2500?

"I have £2500 to spend on my first future classic car and was wondering if you could help? I'm torn between a number of candidates e.g Toyota MR2 MK3, MG TF160, Mercedes SLK 230 or a Mazda MX-5. It will only be used during the summer and needs to be reliable and not too costly to maintain."

All fine cars. I reckon you should go out and drive them - but before you do, make a list of what's important to you. If you want pure driving satisfaction, you make want to go for a Mk1 MX-5, if you like creature comforts then a Mercedes SLK may be more up your street. A car is only reliable as its previous owners, so check the history. Parts prices are a concern with any classic and can be hurt by the fluctuations in currency. You could always price up various items for your shortlist. For example, service items like spark plugs and leads, oil filter etc. Or items like brake pads and discs. But do also check out the prices of panels. Do you have a classic-friendly specialist nearby? How are you planning to store it? You'll need to take these things into consideration, too.

Answered by Keith Moody

Can I repaint the rocker cover on my car?

"I have just bought a 1998 Mercedes-Benz SLK 230. I need advice regarding the rocker cover. On most of the SLK 230s of this vintage the rocker cover is painted white. On my car the front end of the rocker cover has the paint bubbling. Can you advise the likely cause? Can the bubbling paint be stripped and then repainted. If so what paint would you recommend for the job?"

This is a really common problem. The solution is to strip it and re-paint it using Very High Temperature (VHT) paint which you can pick up from most good car parts stores.

Answered by Keith Moody

More Questions

Model History

• January 0001
• January 2000

Mercedes-Benz SLK-Class (1996 – 2004) Buying Guide

Good

Achieved an excellent four star rating for crash safety in 2002 NCAP tests.

Mercedes had fifth lowest average cost in warranty claims for cars up to 10 years old in 2002 Warranty Direct index.

Generally 9th lowest average warranty repair costs in 2003 Warranty Direct Reliability index (index 70.79 v/s lowest 31.93)

Fewest problems and faults, average for breakdowns in 2003 Which survey.

38th in 2007 JD Power Customer Satisfaction Survey with rating of 80.4%.

Bad

Offset driving position.

Original official UK imports were automatic 2.3 'Kompressor' only, so more a two-seat roadster than a 'sports car'.

Autobox changes gear on corners when you don't want it to (manual obviously doesn't). Some problems reported with the 5-speed autobox.

Steering is old-fashioned recirculating ball.

Not much boot space.

Watch

Same severe rust problem as other Mercedes from this period, particularly around wheelarches and doorhandles.

Some sellers may try to base used prices on premium price paid rather than market value (by 2007 you could get one for £6,500k at auction). 

LHD 2.0 litre manual 'personal imports' can be a better bet, down to £6k in spring 2007, under £5k by winter 2007.

Make sure the roof opens and shuts properly. Failure of the roof and windows mechanism of an SLK more than 9 years old can effectively write the car off because it can cost more to repair than the car is worth.

All SLK manuals have suffered from pedal box failures. They are badly designed and fatigue sets in. There are plenty of cases of these failing across the various forums, with MB quoting silly money to replace them the replaced assemblies just failing again. The part that fails is the support for a sprung strut attached to the clutch pedal, to change the feel on actuation, which is odd as the clutch is slightly lighter without it. A reader mod is to remove the unsupported parts as a result of the failure and leave it as is. The biggest risk is that when it actually breaks it makes a very loud bang, and there's a strong chance that the now pivoting sprung assembly will jam the clutch pedal and stop it being disengaged.

Sudden downchanges and misbehaviour of autobox followed by severely rough running may be down to gradual failure of the mass airflow sensor.

On 230K oil can leak through the cam magnet into the wiring harness with consequential damage costing around £700 to remedy. Late 230Ks have an extra oil seal to prevent this from happening.  

Isolated complaints of failures of 6-speed manual gearboxes.

Problems starting to emerge with sensors of folding roof mechanisms if not used regularly.

Foglamps prone to moisture ingress and misting up.

Failure of right side pre-cats and cats of SLK320 V6 quite common and Mercedes quotes £1,400 to replace them. www.carparts-direct.co.uk does them much cheaper.

Older SLKs may suffer intermittent failure of indicators. MB suggests changing the whole CCM at £603 +VAT and labour and next the steering wheel switch if the CCM was not at fault. Mercedes Benz Club´s Technical Director explained in that the CCM can be opened up and that just a new relay can be soldered into place. This can be done for £75 through the Club.

Wheelarches of SLKs reportred to be subject to the same sort of corrosion that has afflicted W202/203 C Class, W210 E Class and W220 S Class. Trunk handle corrosion also very common.

4-5-2013: On manuals the clutch slave cylinder is inside the bellhousing, which makes it a £500 in labour job to replace. When MB delareres change the brake fluid, they do not bleed the slave cylinder as well, leaving contaminated fluid in that circuit.

26-7-2014: Buying Used Mercedes W170 SLK Problem Areas: Rust in wheelarches and panel edges; Roof mechanism failure (hydraulic pump expensive unless can find one second-hand); Supercharger (expensive unless bought second hand); ABS/ESP (diagnostics expensive).

1-5-2017: Severe body rot reported in 30,000 mile 2004 Mercedes Benz R170 SLK 320.

22-5-2017: Standard problem of oil leak fron engine cam into wiring loom reported on R170 2003 Mercedes SLK 230 auto. Engine warming light on. Quoted £3,500 to repair by MB dealer. Suggested seeking out an MB independent who might be able to do the job more viably.