Mercedes-Benz Technical Companion: Insights on Service, Repair, Maintenance and Procedures

This section contains things you can do easily at home to repair and restore your car. We welcome any suggestions from readers.

HORN RING PROBLEMS

Minor, annoying problems with the horn ring tend to plague the W108, W114 and W115 series cars. On some, the horn ring seems to sag closer and closer to the steering wheel, until the horn can only be sounded if the ring is pressed at the top or bottom center. On other models, the ring loosens until a ringing rattle is produced every time the front wheels go over a surface irregularity.

These problems are both caused by the sagging and loosening of a set of springs inside the steering wheel hub. Happily, it is a relatively easy thing to get to them and beef them up.

Pull off the center pad from the steering wheel. This will expose five nuts recessed into the hub. Use a 13-mm wrench and remove them. Remove the spring washers under them, and the wheel will lift off the hub. Use a Phillips screwdriver to remove the horn wires.

With the wheel upside down, you will see three Phillips screws. Remove them, and the component parts will separate. They consist of the wheel, the horn ring, the horn contact unit, and the plate that holds the whole thing together.

Here's a step-by-step, do-it-yourself guide to mending balky mileage counters.

If your VDO odometer has stopped indicating the distance you have traveled, you're not alone. The weakness in this otherwise robust mechanism seems to be the friction fit of a pot metal driving gear on the main odometer shaft. Fortunately, it's easy to fix.

The ideal set of tools for odometer repair includes a set of pin punches, a 2-ounce ball peen hammer, a 7-ounce ball peen hammer, tweezers, a blade-type screwdriver, a jeweler's flat file, slip-joint pliers, a cold chisel, and a bench vise. Still, there's room for considerable improvisation in tools for this job.

DISASSEMBLY

Disassembling the VDO speedometer head from the front will spoil the calibration, so go in from the back. Start by removing the two screws holding the back plate with a screwdriver (Figure 1). With the back plate off, the ends of the main odometer shaft, holding five numbered drums, and the smaller secondary shaft, holding five small sprockets, are visible. On some VDO speedometers it may be necessary to remove the cast metal speedometer drive housing, fastened to the odometer frame with two slotted screws.

• 190D, 190E, 190SL
  
  
• 220D, 220S, 220SE, 230, 230S, 230SL, 240D, 250, 250S, 250SE, 250SL, 280E, 280CE, 280S, 280SE, 280SEL, 280SL
  
  
• 300CD, 300CE, 300D, 300E, 300SD, 300SDL, 300SE, 300SEL, 300TD, 300TE, 350SD, 350SL
  
  
• 400E, 450SE, 450SEL, 450SL
  
  
• 500SE, 500SEL, 560SEL
  
  
• E300D, E320, E420, E430, E500
  
  
• ML320
  
  
• S320, S420, S420, S500, S600

• Technical and Restoration Forum: questions and answers on subjects such as bleeding brakes, aligning headlights, choosing fuel and preparing a vehicle for storage
• Maintenance and preservation procedures — from resetting the service indicator lights to washing and waxing your car
• Heating and air-conditioning system repair including rebuilding the automatic climate control push button unit and converting from R-12 to R-134a
• Driving tips, including the difference between torque and horsepower, and tire selection. You will even find informative diagrams showing oversteer, understeer and vehicle dynamics
• Step-by-step instructions on how to replace shock absorbers and air suspension bellows
• How to choose a shop for maintaining and repairing your Mercedes-Benz
• Fixes for vacuum door locks, mechanical clocks and trip odometers
• Extensive model, chassis number, engine number and production year reference charts: 1946-2005
• Detailed electronic component repairs, such as the Becker Electronic Grand Prix radio and the W210 E-Class seat control switch

• Warnings and Cautions | Foreword | Editor's Introduction
• Lubrication and Maintenance
• Engine, Transmission
• Fuel, Exhaust
• Electrical System
• Body, Interior
• Suspension, Steering, Tires, Wheels
• Brakes
• Heating, Air Conditioning
• Care and Preservation
• Index | Contributor's Index | Art Credits | MBCA Membership Application