General information
The sole purpose of the engine starting system is to ensure that the engine rotates at a speed sufficient to start it.
The starting system consists of a starter, battery, ignition switch, relay and wiring. The solenoid relay is located on the starter housing.
The starter is a DC electric motor with mixed excitation with an electromagnetic traction relay. The starter consists of a housing or stator with excitation windings, an anchor with an overrunning clutch, a cover with brush holders and a traction relay.
When the starter is turned on, current from the battery begins to flow through the winding of the starter traction relay. The relay anchor is pulled in and the contacts close. At the same time, the relay anchor moves the overrunning clutch with the gear through the lever. The hub of the overrunning clutch rotates on the helical splines of the starter anchor shaft and also rotates the gear, which facilitates its engagement with the flywheel ring gear. Current flows through the closed contacts of the traction relay, feeding the stator and anchor windings, and the starter anchor begins to rotate together with the hub and overrunning clutch.
After the engine is started, the rotation speed of the pinion exceeds the rotation speed of the starter anchor. In this case, the overrunning clutch rotates freely, and the torque is not transmitted from the engine flywheel to the starter anchor shaft. After releasing the ignition key, the power supply circuit of the traction relay windings through the ignition switch is opened, the anchor of the traction relay is pressed back to its original position by the spring, the relay contacts are opened and the drive pinion disengages from the flywheel ring gear.
The starter with a solenoid relay is located parallel to the engine crankshaft and is fixed to the gearbox. The starting system circuit relay is located in the main block under number 17.
The starter is engaged only if the AT selector is in position "P" or "N".
If the vehicle is in the security mode, the starter will not turn.
Precautionary measures
When performing any work on the engine starting system, observe the following requirements:
- a) Do not keep the starter on for a long time. It may overheat and fail. Do not turn on the starter for more than 15 seconds, and wait about two minutes before turning it on again. If you crank the starter for a long time and the engine does not start, unburned fuel will accumulate inside the converter. This may cause the working surface of the converter to overheat after the engine starts;
- b) The starter is connected directly to the battery and if handled carelessly it may catch fire or cause a short circuit;
- c) Always disconnect the battery ground cable before starting work.
Publication reprinted from this resource: MercedesMAN