1990 Mercedes-Benz 420SEL Repair and Maintenance
A guide to problems, costs, maintenance and repair for your 1990 Mercedes-Benz 420SEL
- Bad Switch/Blower Motor Resistor Assembly May Cause Inoperative Heater Blower Motor
- Stuck Idle Air Compensator May Cause Too High/Too Low RPM
- Replace timing chains/guides every 100,000 miles
- Rubber boot connecting throttle body to intake manifolds may crack
- Valve Stem Seals Wear and Cause Catalytic Converter Failure
1990 Mercedes-Benz 420SEL Problems
Other than a defective motor, a bad switch or blower motor resistor assembly can cause an inoperative heater blower motor.
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.timing chain and timing chain guides wear; they should be replaced every 100,000 miles.
1990 Mercedes-Benz 420SEL Questions
Problem occurs when put in fuel
Power steering reservoir?
Car starts fine with full power when cold but looses power as it warms up. It never cuts out but can only be driven very slowly with little power