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Resources for the Repair and Maintenance of your Mercedes-Benz 420SEL

Mercedes-Benz 420SEL Models:

Image for car images Mercedes Benz 1990 1991 Mercedes Benz 420 SEL size thumb

Mercedes-Benz 420SEL Problems

Bad Switch/Blower Motor Resistor Assembly May Cause Inoperative Heater Blower Motor

Heating & Air Conditioning -- Verified

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

Engine -- Verified

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

Engine -- Verified

The timing chain and timing chain guides wear; they should be replaced every 100,000 miles.

Shifter Lever Bushings May Break Causing Loose Feel/Noise

Drive Train -- Verified

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.

Rough Running Engine Due to Misfire

Exhaust & Emissions -- Verified

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.

Mercedes-Benz 420SEL Questions and Answers

tx77703, 1990 Mercedes-Benz 420SEL, Beaumont, TX

1989 420 sel new valve job having problems hard to start when cold and after driving up to normal temp also the eco neelde stays in center when at a red light and the car is in gear

u.perpar, 1990 Mercedes-Benz 420SEL, Indiana, PA

what is coreect atf fluid for 420 sel and where does it get filled once drained

RC90, 1990 Mercedes-Benz 420SEL, Oakdale, CA

car stalled while on the road. plenty of fuel(half tank) turns over fine. no prior problems. Any suggestions or ideas

JNM, 1990 Mercedes-Benz 420SEL, Richmond, TX

I have a 1986 420 SEL and had to replace the window. The plastic clip which is used to attach the window rotor to the actual glass was broken and I went to the dealership and got a new one. How d...

Visitor, 1990 Mercedes-Benz 420SEL, Aurora, CO

what would effect my tranny shifting down from 3rd to 2nd or when I'm slowing down 2nd to 1st,is it a vacuum problem or something more serious

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Mercedes-Benz 420SEL Stories

great car!! still a head turner after almost 20years.. have owned my 91 420sel now for 5 years and still performs, looks, handles and drives like brand new with only 150k...maintenance can be costly..GREAT Highway cruiser..no cup holders :( .. last of the big(long) dinosaurs..

THE HANDLING REALLY NICE THE VENT DOES NOT OPENING TOOK ME FOR AWHILE TO GET AC ON ALMOST 1991 S CLASS HAVING PROBLEM WITH CRUISE CONTROL SWITCH IT'S DOESN'T WORKING SOME TIMES DOES.I'VE GOT BAD FUEL PUMP ON BOTH LEAKING TO REPLACED COST ME $500.000.

what other automobile would you even consider that has 150k miles and still cost $5k or better..and get a consistent thumbs up!

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