Problem Reports
Problem with your car? See what our experts say or submit your own.
1990 Mercedes-Benz 420SEL Problems
Bad Switch/Blower Motor Resistor Assembly May Cause Inoperative Heater Blower Motor
Other than a defective motor, a bad switch or blower motor resistor assembly can cause an inoperative heater blower motor.
Incorrect Idle Speed Due to Stuck Idle Air Compensator
It is not uncommon for the idle air compensator to get stuck in one position, resulting in the engine idle speed (rpm) being too high or too low. Replacement of the failed compensator may be necessary to correct this concern.
Replace timing chains/guides every 100,000 miles
Rubber boot connecting throttle body to intake manifolds may crack
Catalytic Converter Failure Due to Engine Burning Oil
Valve stem seals may wear and cause the engine to burn oil. this can contaminate the catalytic converter and cause it to fail.
"No start" Caused by Failed Fuel Pump/Relay
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.
Shifter Lever Bushings May Break Causing Loose Feel/Noise
The bushings for the shifter lever wear out to the point where they break and fall out. This causes excessive movement (loose feel) in the shifter lever and a clanging-type noise when changing gears.
Power steering hoses can develop leaks
Rear spring wear may cause rear end to sag on high mileage vehicles
Excess Free Play in Steering and/or Alignment Issue
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.
Expansion valve may get stuck
ABS Modulator Failure Due to Dirty Brake Fluid
As brake fluid becomes dirty over time, it can cause a failure of the anti-lock brake system (ABS) modulator assembly. Our technicians recommend a complete brake system flush every two years to help prevent this issue.
Cracked Driveshaft Flex Discs May Cause Driveshaft Movement/Vibration
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.
Transmission Oil Seals May Leak on High Mileage Vehicles
High mileage vehicles may develop a transmission fluid leak from one or more of the oil seals.
The Differential May Develop Leaks From the Seals or Cover
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.