How to tell if your starter is bad

As we know, the engine needs external forces to start, the starter is playing this role. The starter can convert the electric energy of the battery into mechanical energy and drive the  engine flywheel to start the engine. In general, the starter has three components for the entire starting process. The DC motor introduces the current from the battery and causes the driving gear of the starter to move mechanically. The drive gear meshes with flywheel ring gear by the transmission mechanism, and can be automatically disengaged after the engine starts. The on and off of the starter circuit is controlled by a solenoid switch. The motor is the main internal component of the starter, and its working principle is the energy conversion process based on ampere's law, the effect of the current conductor on the force in the magnetic field. The motor includes the necessary armature, commutator, magnetic pole, brush, bearing and housing, etc.

Common causes of a bad starter


1. After switching on the starting switch, the starter rotates at high speed and the engine crankshaft has no reaction. This phenomenon indicates that the fault occurred in the transmission mechanism of the starter, which may be caused by wear of the transmission gear or one-way clutch.


2. The starter cannot work normally, and the driving gear does not turn. There are many reasons for this, such as power line problems, starting switch contact plate ablation and excessive engine resistance. 


3. The starter power output is insufficient, unable to drive the crankshaft. Short circuit of excitation coil and battery loss can cause insufficient power of starter.


4. The sound of starter running is grinding. This may be caused by a jammed one-way clutch or improper starter installation.


5. The starter switch has a "tap" sound, but does not work. This can occur if the coil is kept disconnected or the battery is seriously depleted.


How to tell if your starter is bad


When starting, turn the ignition switch to the starting gear, if the starter has no rotation, you should first check the light, if normal, continue with the following inspection.


(1) Check whether the ignition switch can conduct the starting circuit, whether the connection between the ignition switch and the breaker wire of the starter is reliable, whether the relay is damaged, whether the contact is seriously ablated, etc.

(2) Check whether the starter solenoid switch contacts are ablated or improperly adjusted to affect conduction.


When checking the light, if it is dim, you should check as follows:


(1) Check whether the connection between the battery terminal and the conductor is reliable and whether the voltage is normal.

(2) Internal malfunction of starter. Such as serious short circuit, rotor stuck etc.

(3) Excessive resistance of engine operation.

2. The starter spins but the engine does not crank, commonly known as "idling". At this point, you can open the clutch bottom housing, check the starter rotation. If the starter gear can engage with the flywheel gear ring, the reasons may be.

(1) The one-way meshing of the starter is damaged, which should be repaired or replaced;

(2) The interference amount of the flywheel gear ring is too small, and the gear ring rotates on the flywheel. In this case, anti-rotation screws should be added or new tooth rings should be replaced and interference should be checked to see if it is in accordance with the regulations. If the starter gear cannot engage with the flywheel gear ring, check the timing of adjusting the travel of the meshing gear or the magnetic switch to turn on the power.


3. The starter operation is weak. There are many reasons for this fault, so the following aspects should be emphatically checked.


(1) The wire contact, especially the battery terminal contact should be reliable.  

(2) The battery has been used for too long and lead to capacity decline or the battery capacity is too small.

(3) Starter magnetic switch contact ablation, increasing resistance.

(4) Excessive brush wear, small brush spring pressure, commutator surface ablation or serious dirt.

(5) If the starting mechanical and electrical pivot is bent or the clearance between the shaft and the copper sleeve is too large, the rotor and stator will scratch during operation.

(6) Starter armature, magnetic field coil partial short-circuit or joint virtual welding, etc. 

(7) Engine assembly is too tight, oil viscosity is too large and cause engine running difficulties.


4. The starter gear and flywheel ring gear have a sound of a crash.

1. Check whether the gear of the starter and flywheel ring gear wear too much and affect smooth meshing.

2. Whether the clearance between starter gear and thrust washer is too small.

3. Whether the power conduction time of starter magnetic switch is too early, so that the starter gear has not been meshed.


5. After the ignition switch disconnects the starting circuit, the starter still keeps running.


(1) Check the ignition switch whether is short circuit.

(2) Whether the starter magnetic switch contacts are sintered together so that the circuit cannot be disconnected.

(3) The return spring of the starter meshing shift fork is broken or too soft, so that the starter gear cannot be separated from the flywheel ring gear. As soon as this kind of fault occurs, immediately disconnect the battery grounding. Otherwise, you may burn out the starter very quickly. At the same time, it also leads to a large number of battery discharge, affecting its service life.

6. After the ignition switch is connected to the starting circuit, there is an intermittent ticking sound but the starter cannot turn.

In this case, a wire can be used to conduct the "power supply" and "start" by connecting columns of starter relay. If starter works normally and the fault is in the relay, relay contacts should be repaired or replaced. If the starter still does not turn, check the spark strength when conducting two columns. If the spark is strong, indicates fault in the starter, the cause of armature coil or magnetic field coil short circuit, circuit ground. If the spark is weak, the fault is in the power supply system, the cause is battery damage or too low capacity, improper contact of circuit etc.