2008 Mercedes-Benz B-Class diesel: common problems and MOT failures

What goes wrong more than usual on a 2008 Mercedes-Benz B-Class diesel?

Parts flagged at MOT more often on the 2008 Mercedes-Benz B-Class diesel than on all cars registered in 2008.

• Rigid brake pipes3.3× usual
  Mercedes-Benz B-Class

  31% All 2008 cars

  9.3%

  Failed outright at MOT: 5.9%, against 1.7% of all 2008 cars. The rest were advisories or minor defects.

  Rough price £100–£400 our estimate

  At the viewing: Ask to see underneath, or check the MOT advisories: corroded brake or fuel pipes get worse every year and fail the MOT when they do.

• Drive shaft (CV) joints3.1× usual
  Mercedes-Benz B-Class

  20.8% All 2008 cars

  6.7%

  Failed outright at MOT: 10.4%, against 3% of all 2008 cars. The rest were advisories or minor defects.

  Rough price £60–£350 our estimate

  At the viewing: Drive slowly on full steering lock in both directions and listen for clicking. Look for split rubber boots behind the front wheels.

• Ball joint2× usual
  Mercedes-Benz B-Class

  12.4% All 2008 cars

  6.3%

  Failed outright at MOT: 7.4%, against 3.2% of all 2008 cars. The rest were advisories or minor defects.

  Rough price £60–£150 (one joint) ClickMechanic

  At the viewing: Listen for knocking over bumps and check the rubber boots behind the wheels aren't split.

• Corroded fuel pipes9× usual
  Mercedes-Benz B-Class

  5.4% All 2008 cars

  0.6%

  Failed outright at MOT: 0%, against 0% of all 2008 cars. The rest were advisories or minor defects.

  Rough price £100–£400 our estimate

  At the viewing: Ask to see underneath, or check the MOT advisories: corroded brake or fuel pipes get worse every year and fail the MOT when they do.

• Washers1.9× usual
  Mercedes-Benz B-Class

  7.1% All 2008 cars

  3.8%

  Failed outright at MOT: 7.1%, against 3.8% of all 2008 cars. The rest were advisories or minor defects.

  Rough price £15–£60 our estimate

  At the viewing: Test the wipers and washers on every speed.

Common 2008 Mercedes-Benz B-Class diesel MOT failures and advisories

The share of 2008 Mercedes-Benz B-Class diesel MOT tests where testers flagged each area, as a fail or an advisory. Rough prices are typical independent-garage costs.

• Brakes
  55% 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.

• Suspension
  42% 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.

• Tyres
  35% 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.

• Lights and electrics
  30% of testsRough price £10–£80

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

• Driveshafts and joints
  21% of testsRough price £60–£350

  At the viewing: On full steering lock, drive slowly and listen for clicking from the front wheels.

• Wipers, windscreen and mirrors
  13% of testsRough price £15–£250

  At the viewing: Check for chips in the driver's view, and test the wipers and washers.

Questions to ask the seller before buying a 2008 Mercedes-Benz B-Class diesel

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

1. Any recent work on the rigid brake pipes? (Flagged at MOT 3.3× as often on the 2008 Mercedes-Benz B-Class diesel as on other cars the same age.)
2. Any recent work on the drive shaft (cv) joints? (Flagged at MOT 3.1× as often on the 2008 Mercedes-Benz B-Class diesel as on other cars the same age.)
3. Any recent work on the ball joint? (Flagged at MOT 2× as often on the 2008 Mercedes-Benz B-Class diesel as on other cars the same age.)
4. Can I see the service history and receipts for any big jobs?