Engine Starting System

Ease of starting is one of the major performance characteristics of internal combustion engines. To start such an engine, it is necessary to spin the engine crankshaft with sufficient speed. The minimum speed with which the crankshaft of an engine should be rotated to ensure reliable starting of the engine is referred to as the cranking speed. The starting speed is 40 to 50 rpm for carburetor engines and 150 to 250 rpm for diesel engines.

The starting system provides the power to turn the internal combustion engine over until it can operate under its own power. To perform this task, the starter motor receives electrical power from the battery, and it converts this energy into mechanical energy, which transmits through the drive mechanism to the engine’s flywheel. The drive mechanism engages and disengages the pinion gear from the flywheel. The typical starting system consists of battery, cables, ignition switch, starter relay, starter control circuit , neutral safety switch, fuse, starter solenoid and starter motor.

When you turn the ignition key to the “Start” position, the battery voltage goes through the starter control circuit and activates the starter solenoid, which in turn energizes the starter motor. The starter motor cranks the engine.

There is a Neutral safety switch installed at the automatic transmission. (or at the clutch pedal), When the automatic transmission is not in Park or Neutral ( or when the clutch pedal is not depressed) , the neutral safety switch is open and the starter relay disconnects the starter control circuit. When the transmission is in Park, the switch is closed. Current causes the

solenoid to engage the starter, and the engine starts.

Safety Tips

(1) Do not use the method of beating the starter motor to diagnose the drive failure of the starter motor. A knock may dislodges the brushes, armature and front sleeve. The knocked motor, even if it can run, is only for a short time.

(2) The electrolyte in the battery contains sulfuric acid. Sulfuric acid is a very corrosive acid that can cause serious harm to humans. Be sure to pay attention to safety when filling electrolyte.

(3) It is forbidden to bury or burn acid lead-containing waste batteries.

(4) Regardless of whether the battery is new or old, it should be placed indoors, and good ventilation should be maintained.

(5) Gloves, rings and other jewelry should not be worn when working, because they may come into contact with the automotive electrical system or parts in operation.