The primary task of the ignition system in Mercedes Benz vehicle is to ignite the fuel at exactly the right time so that the expanding gases can do the maximum amount of work. It is usually switched on and off through a lock switch operated with a key or a code patch. If the ignition system fires at the wrong time, power will fall and gas consumption and emissions can increase. Because of this task, the ignition system is considered an important part of the overall engine system.


And for that spark to be made, subcomponents are needed to do such tasks. This includes the sparkplugs, ignition coil and the distributor. The distributor deserves more credit as performs various functions like distributing high voltage from the coil to the correct cylinder and breaking the current to the coil.


Working in tie-up with the distributor cap in the distributor assembly, the Mercedes distributor rotor distributes electricity from the ignition coils to the spark plug wires at the right timing. It switches high-sparking voltage from the spark plugs to fire in correct sequences.


The metal part of the Mercedes distributor rotor contacts the central high voltage cable from the coil via a spring loaded carbon brush. The metal part of the rotor arm passes close to (but does not touch) the output contacts which connect via high tension cables to the spark plug of each cylinder. As the rotor spins within the distributor, electrical current is able to jump the small gaps created between the rotor arm and the contacts due to the high voltage created by the ignition coil.


The firing end of the Mercedes distributor rotor is from where the high tension spark jumps to each of the cap terminals. It should not be worn because wearing out will result in resistance to the high tension spark. A worn firing end of the rotor requires immediate replacement. The rotors are mounted on the upper end of the distributor shaft. Thus, the Mercedes distributor rotor must have a snug fit on the end of the shaft. With other designs, two screws are used to attach the rotor to a plate on the top of the distributor shaft. Built-in locators ensure correct reassembly. These are found at the rotor and holes in the plate. One of which is round while the other is square.