1990 Mercedes-Benz 300SEL Problems
RepairPal has identified the most common problems with the 1990 Mercedes-Benz 300SEL based on complaints from actual vehicle owners. We'll tell you what the problem is and what it'll take to fix it.
Other than a defective motor, a bad switch or blower motor resistor assembly can cause an inoperative heater blower motor.
A rough running motor or lack of power can be caused by a failed distributor cap or rotor, ignition wires (or their resistors), or valve cover gasket leaks. If the valve cover gasket leaks, oil can pool where the ignition wire resistor connects to the spark plug. The resistor can fail and the spark plug may not fire because of a short circuit through the oil.
The fuel pump and/or fuel pump relay can fail, causing the car to crank over but not start. Proper diagnoses will be necessary to confirm if the pump or relay is at fault.
Leaks may develop from the differential seals and/or cover on older or high mileage vehicles. Our technicians recommend a complete reseal of the differential unit when these leaks are addressed.
A vibration felt through the center floor of the vehicle can be caused by cracked and/or shredded driveshaft flex discs, resulting in excessive driveshaft movement. If not repaired, damage to the driveshaft center support bearing, transmission, or differential can occur.
The tie rod ends, idler arm, and/or drag link components of the steering linkage may wear prematurely. Please keep in mind the wheel alignment should be checked and adjusted when any of these items are replaced.
The emissions air injection pump can seize, causing a loud squealing noise followed by smoke from the drive belt. If the engine is not turned off, the belt will break, turning on the alternator/battery warning light.
The lower control arm bushings can wear and crack, leading to irregular and premature tire wear. Worn Ball joints can also cause similar tire wear problems. I some cases it may be necessary to replace the lower control arm, including bushings & ball joint to correct this concern.
A coolant leak may develop from the water pump. When replacing the water pump, the drive belt tensioner should be inspected and most likely replaced as well.
Due to wear, high usage vehicles can experience ignition lock and tumbler failures. The ignition lock cylinder will generally require replacement to correct this concern.
A coolant leak may develop form the Radiator due to degradation of its plastic components. Replacement of the failed radiator will be necessary.