Common problems: recent Mercedes models
123 cars — the 240 and 300D variants from 1977-1985
These are excellent cars. At this time their weakness is body corrosion. Look for rust in the rocker sills, the frame rails, around the rear suspension and in the wheel arches and quarters.
Rust free examples are hard to find.
The other weakness is the transmissions. The diesel engine torque beats the transmissions to death. We have had the best luck installing genuine Mercedes rebuilt units.
124 cars — the 1986-1995 E Class cars
The wire used to make the harnesses between 1992 and 1995 becomes brittle from heat, and the insulation breaks off. If you see cracking insulation on bare wire in the engine harness — beware. The cure is a new engine harness, which can cost upwards of $1,000.
The front struts in these cars become noisy and bang and rattle over bumps. With other models loose links cause rattles but in these cars noises often come from the struts themselves.
126 cars — the 82-91 S Class
The 6 cylinder 300 engines are prone to develop head gasket leakage at the front of the head, in the timing chain area.
The 8 cylinder engines are prone to leak oil from the left head gasket. 560 motors are the worst in this regard.
The 8 cylinder engines have weak timing chain tensioners. When starting the car you may head a brief rattle from the motor — especially just after an oil change. If you hear this you should change the tensioner right away as there may be no other warning before the chain skips, bending the valves and causing $5,000 damage.
140 cars — the 92-99 S Class
The 6 cylinder engines are prone to develop head gasket leakage at the front of the head, in the timing chain area.
The electronic transmissions used since 1996 were filled with "permanent" fluid. We find that the fluid darkens as a result of picking up graphite from the clutches, and if left unchanged this fluid darkens the sensor windows inside the unit, leading to electronic faults. We suggest 60-90,000 mile fluid changes.
The electronic transmissions used since 1996 are prone to damage if something spills into the center console. The electronic selector can call for two gears at once, resulting in expensive damage. Don't ever drive with liquids on the shift housing.
The lower control bushings become loose around 120,000 miles and the result is a vibration you can't seem to repair. It feels like tire balance but it's not. Check for loose rubber bushings at any major service.
The air conditioner evaporator cores are prone to failure. Repair is a big job, often 24-30 hours.
These were the first cars built by Mercedes with fiber optic signaling and CAN bus technology. Being the first cars of this design the diagnostic technology is somewhat limited.
203 cars — the 2000-up C Class
The 100,000 mile replacement interval for spark plugs puts considerable strain on ignition components. Firing voltage rises as the plugs age. The result is often a need to change ignition wires and coil packs just over 100,000 miles. We suggest replament of spark plugs at 75-90,000 miles to reduce the chance of ignition failures.
These cars are prone to problems with the interaction of the various computer systems on the CAN bus. A number of Internet sites discuss these problems.
463 cars — late model G500 sport utilities
Gravel and water spray up behind the rear tires and corrode the connections to the fuel purge valve and marker lights on the right side of the vehicle. We have seen several units with this problem.
The door latches are prone to rattle. You can adjust them but at this time we are not aware of a permanent cure.
We have found the Michelin tires perform a lot better than the original equipment Yokohama Geolanders.