2004 Mercedes-Benz SLK: common problems and MOT failures

What goes wrong more than usual on a 2004 Mercedes-Benz SLK?

Parts flagged at MOT more often on the 2004 Mercedes-Benz SLK than on all cars registered in 2004.

• Steering rack2.5× usual
  Mercedes-Benz SLK

  4.2% All 2004 cars

  1.7%

  Failed outright at MOT: 3.1%, against 1% of all 2004 cars. The rest were advisories or minor defects.

  Rough price £100–£450 our estimate

  At the viewing: On a straight road the steering wheel should sit straight. Listen for knocks when turning, and check the steering feels even.

• Rust around sub-frame mountings1.7× usual
  Mercedes-Benz SLK

  2.2% All 2004 cars

  1.3%

  Failed outright at MOT: 0.4%, against 0.3% of all 2004 cars. The rest were advisories or minor defects.

  Rough price £300–£1,000 our estimate

  At the viewing: Look underneath at the frame the suspension bolts to. Flaky rust or holes are expensive to fix.

Common 2004 Mercedes-Benz SLK MOT failures and advisories

The share of 2004 Mercedes-Benz SLK MOT tests where testers flagged each area, as a fail or an advisory. Rough prices are typical independent-garage costs.

• Suspension
  36% of testsRough price £120–£400

  At the viewing: Listen for knocks over speed bumps, and look behind each front wheel for a snapped coil spring.

• Brakes
  33% of testsRough price £150–£350

  At the viewing: Look for a lip on the disc edges and feel for judder or pulling when braking firmly from about 40mph.

• Lights and electrics
  27% of testsRough price £10–£80

  At the viewing: Ask a friend to check every light, including brake lights and indicators, while you operate them.

• Tyres
  26% of testsRough price £70–£150

  At the viewing: Check the tread on all four tyres, including the inside edges, and look for cracks or bulges.

• Oil and fluid leaks
  8% of testsRough price £80–£600

  At the viewing: Look under the engine and on the ground where the car is usually parked for fresh oil or fluid.

• Exhaust and emissions
  8% of testsRough price £100–£1,200

  At the viewing: Look for black soot in the tailpipe, listen for blowing from the exhaust and check for engine or DPF warning lights.

Known faults on the 2004 Mercedes-Benz SLK

Reported by owners, mechanics and buying guides for this model and age. Check which engine the car has, as some apply to one engine only.

• Roof motors and pump

  All engines

  The roof motors can seize if the roof stays up for long periods, and a slow roof usually means a failing pump. Both are costly.

  At the viewing: Open and close the roof several times and time it.

  Source: What Car?: used Mercedes-Benz SLK (2004-2011) reliability

• Leaking boot seals

  All engines

  Boot seals fail often, letting water collect in the spare wheel well.

  At the viewing: Lift the boot floor and look for water or damp.

  Source: What Car?: used Mercedes-Benz SLK (2004-2011) reliability

Questions to ask the seller before buying a 2004 Mercedes-Benz SLK

Ask before you travel to see it. A seller who knows the car will have answers, and receipts.

1. Has the roof had any work?
2. Any recent work on the steering rack? (Flagged at MOT 2.5× as often on the 2004 Mercedes-Benz SLK as on other cars the same age.)
3. Any recent work on the rust around sub-frame mountings? (Flagged at MOT 1.7× as often on the 2004 Mercedes-Benz SLK as on other cars the same age.)
4. Can I see the service history and receipts for any big jobs?