Mercedes-Benz W163 alternator and fluctuating charging voltage
Mercedes-Benz W163 charging voltage fluctuates and the instrument cluster acts up, what is wrong?
Voltage can climb as high as 16-17 volts while driving, which resets the instrument cluster and makes the lights flicker. The cause is usually the alternator freewheel clutch, the voltage regulator or bad ground points. The alternator can also have more than one fault at the same time.
How do you recognise a faulty Mercedes-Benz W163 alternator freewheel clutch?
The freewheel clutch shaft clicks or wobbles while the engine is running, and when turned by hand the clutch feels like it grips in only one direction. Replacing the freewheel clutch evens out the charging. The alternator has to be removed, and the job takes about 2.5 hours.
Does cleaning the ground points help with Mercedes-Benz W163 charging problems?
Yes, bad grounds cause the same symptoms. Clean the ground point next to the battery and the ground cable between the engine and the subframe, and also check the positive connections behind the battery.
How do you identify the alternator size on a Mercedes-Benz W163 270 CDI before ordering a part?
Identify the alternator by its electrical connections. On the Bosch alternator (150 A) the wires are at the front. On the water-cooled 190 A alternator the connector is oval and located at the rear. A water-cooled alternator is usually not repaired but replaced.