1990 Mercedes-Benz 300SL Repair and Maintenance

A guide to problems, costs, maintenance and repair for your 1990 Mercedes-Benz 300SL

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1990 Mercedes-Benz 300SL 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.

Poor AC Performance Due to Refrigerant Loss

A refrigerant leak may develop from one or more of the following AC components: AC compressor, hose manifold for the compressor, or the evaporator core. The loss of refrigerant can cause poor AC performance. Our technicians tell us that proper leak diagnoses should be performed in order to determine the cause of any refrigerant loss.

Rough Running Engine Due to Misfire

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.

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1990 Mercedes-Benz 300SL Questions

I have problems with the instrument cluster. (1 answer)

The meters are going up and down sometimes. Eventually it may brake down completely some workshop guy told me.
Any tips for what to do? Is he right? What will be the price for a new or used one?

My row bar keeps coming up when I make a turn. (1 answer)

The hard top is on when I make the turn.

Where do u check for hydraulic fluid on hard top? Hard top not unlatching. (1 answer)

Red light is on.

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1990 Mercedes-Benz 300SL Reviews

Nice car but does have a number of issues after 20+ years. There is a wealth of information and help on the MB forums. The bad "green" wires came in 1994 for a few years. And, EZL's do NOT explode. (Where does this stuff come from?)
the best car I ever had
1) the electrical wire issue. Basically this makes the car a rolling wreck with it only a matter of time before they short out and your entire computer system and or EZL explodes...anyone out there care to guess how much that would cost (an EZL for this particular car is extremely expensive) I was told that the insullation was designed to be GREEN and biodegrade...which is why it falls apart......

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