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How Does it Work /
Starter and Solenoid
How Does a Starter and Solenoid Work?
Introduction:
An engine starter is designed to utilize a 12 volt, high amperage electrical
system made to turn an engine over for starting purposes via a flywheel.
Basically a starter is an electric motor with a small pinion gear and bendix
assembly. This starter bendix drive is designed to extend and mesh with the
flywheel teeth when the ignition key is turned to the "crank" position and then
retract when the ignition key is released after the engine has started. A
starter motor is constructed with a main outer housing that contains the
armature magnets, the armature contains the starter windings, a brush set that
is used to contact the armature to transfer the electrical energy. The starter
bendix is directly connected to the starter pinion gear. A starter solenoid acts
as the main power switch to begin the starter operation. Because the starter
motor draws such high amperage a conventional switch would short circuit very
quickly. Most starter solenoids are located on the starter motor itself. Some
Ford models have located the starter solenoid on the inner fender panel near the
battery. The electrical system that controls the starter motor is comprised of
an ignition switch, neutral safety switch (automatic transmissions only) a
clutch engagement switch (manual transmissions only) a battery, battery cables,
anti theft system and the starter itself.
Typical Starter Motor
Most starter motors are mounted underneath the car near the flywheel on
either the left or right side. The flywheel is located between the engine and
transmission. Some models have located the starter under the intake manifold,
which makes replacement difficult. When the ignition key is turned to the
"engine crank" position a 12 volt low amperage electrical signal is sent to the
anti-theft system which in turn can monitor the gear selection or clutch safety
switch position. Only then will the signal continue to the starter solenoid that
activates the high amperage side of the electrical system to engage the starter
motor.
Starter Solenoid (appearance will vary)
Once the starter motor has been engaged the starter bendix senses the armature momentum and is forced to extend into the flywheel.
Once the engine has started and the ignition key released the bendix loses
momentum and the bendix is forced to return to idle position. If the flywheel is
worn it can cause a grinding noise when the starter bendix/pinion gear is
engaged. The objective of the starter motor is to rotate the engine between 85
and 150 rpm's necessary for engine ignition process. A starter will typical
last between 60,000 and 100,000 miles and is a normal replacement item.
Starter Bendix (appearance will vary)
Replacement Guide
Tools needed:
- Set of sockets and socket wrench with extensions
- Phillips and standard screw drivers
- Pliers
- Wrench set
Replacement Procedure:
- Start with engine cold
- Remove the negative battery cable at the battery
- Remove all electrical wires that lead to the wiring harness and main
battery cable connections. (note: sometimes this step is easier after the
starter motor has been removed)
- Remove all accessories (if any) to access starter motor mounting bolts,
next remove starter motor mounting bolts, remove the starter.
- Clean starter mounting surfaces
thoroughly
- Install new starter and tighten evenly
- Reconnect wiring and cable
- Reconnect the negative battery cable (note: if major spark are present
when the battery is re-connected the starter battery connection needs to be
inspected)
- Recheck starter operation (note: if the starter motor operation is
excessively noisy the starter motor may need to be repositioned using shims)
Typical Starter Wiring Circuit
Related Replacement Components:
Basic Checks
The starter will not operate properly without the correct voltage needed. To
test the electrical system voltage use a voltage meter
(voltmeter).
Attach the voltmeter leads to the positive and negative terminals of the
battery. To check a battery surface voltage, remove the positive terminal protective
cover and connect the +positive side meter lead (red) to the positive side battery
terminal then connect the - negative (black) side meter lead to the negative
battery
terminal. With the vehicle not running and sitting over night the
battery voltage should be between 12.4 and 12.6 volts. To test the system
without a volt meter activate the headlights, if they illuminate brightly the electrical system
probably has sufficient voltage. If
the headlights are dim or not working the battery charge is either low or the battery has failed and needs
replacing.
Starter electrical system inspection
Common Problems
- Starter Drag: This condition exists when the start motor rolling bearing
has failed allowing the armature to contact the outer starter motor case
creating a
scraping noise.
- Starter Motor Rapid Clicking Sound: When the starter motor makes a rapid
clicking noise it can mean the battery is too low on charge.
Check battery condition
- Starter Motor Grinds When Cranking: This condition exists when the
starter bendix or flywheel has worn and is causing the gear mesh to fail
creating a grinding noise.
- Starter Makes a Ticking Noise: This condition is created when the
starter solenoid connection plate has shorted not allowing the electrical
flow to continue through to the starter motor itself. Or the starter brushes
have failed also not allowing the electricity through to the starter
armature.
- Starter Clunk/Bang Noise: A clunking/banging noise when the starter is
engaged could mean the starter is working ok but the engine is not turning
over. Manually try to turn the engine over to confirm engine failure. Engine
failures can include blown head gasket, crankshaft failure, intake/exhaust
valve failure, connecting rod failure or piston failure.
How Does it Work
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Starter and Solenoid
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Starter and Solenoid
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