Crown Victoria V8-4.6L SOHC VIN 6 (1996)
Starter Motor: Testing and Inspection
Testing Notes
To obtain full performance data on a starting motor or to determine the cause of abnormal operation, the starting motor should be submitted to a no-load
and torque test. These tests are best performed with the starter mounted on a starter bench tester.
From a practical standpoint, however, a simple torque test may be made quickly with the starter in the car. Make sure the battery is fully charged and that
the starter circuit wires and terminals are in good condition. Then operate the starter to see if the engine turns over normally. If it does not, the torque
developed is below standard and the starter should be removed for further checking.
When trouble develops in the starting motor circuit, and the starter cranks the engine slowly or not at all, several preliminary checks can be made to
determine whether the trouble lies in the battery, in the starter, in the wiring between them, or elsewhere. Many conditions besides defects in the starter
itself can result in poor cranking performance.
To make a quick check of the starter system, turn ON the headlights. They should burn with normal brilliance. If they do not, the battery may be run
down.
If the battery is in a charged condition so that lights burn brightly, operate the starting motor. Any one of three things will happen to the lights: (1) They
will go out, (2) dim considerably, or (3) stay bright without any cranking action taking place.
IF LIGHTS GO OUT:
If the lights go out as the starter switch is closed, it indicates that there is a poor connection between the battery and starting motor. This poor
connection will most often be found at the battery terminals. Correction is made by removing the cable clamps from the terminals, cleaning the
terminals and clamps, replacing the clamps, and tightening them securely. A coating of corrosion inhibitor may be applied to the clamps and
terminals to retard the formation of corrosion.
IF LIGHTS DIM:
If the lights dim considerably as the starter switch is closed and the starter operates slowly or not at all, the battery may be run down, or there may
be some mechanical condition in the engine or starting motor that is throwing a heavy burden on the starting motor. This imposes a high discharge
rate on the battery which causes noticeable dimming of the lights.
Check the battery state of charge. If it is charged, the trouble probably lies in either the engine or starting motor itself. In the engine, tight bearings
or pistons or heavy oil place an added burden on the starting motor. Low temperatures also hamper starting motor performance since it thickens
engine oil and makes the engine considerably harder to crank and start. Also, a battery is less efficient at low temperatures.
In the starting motor, a bent armature, loose pole shoe screws or worn bearings, any of which may allow the armature to drag, will reduce cranking
performance and increase current draw. In addition, more serious internal damage is sometimes found. Thrown armature windings or commutator
bars, which sometimes occur on overrunning clutch drive starting motors, are usually caused by excessive overrunning after starting. This is the
result of such conditions as the driver keeping the starting switch closed too long after the engine has started, or the driver opening the throttle too
wide in starting. Any of these subject the overrunning clutch to extra strain so it tends to seize, spinning the armature at high speed with resulting
armature damage.
Another cause may be engine backfire during cranking which may result, among other things, from ignition timing being too far advanced. To
avoid such failures, the driver should pause a few seconds after a false start to make sure the engine has come completely to rest before another
start is attempted. In addition, the ignition timing should be checked if engine backfiring has caused the trouble.
LIGHTS STAY BRIGHT, NO CRANKING ACTION:
This condition indicates an open circuit at some point, either in the starter itself, the starter switch or control circuit. The solenoid control circuit
can be eliminated momentarily by placing a heavy jumper lead across the solenoid main terminals to see if the starter will operate. This connects
the starter directly to the battery and, if it operates, it indicates that the control circuit is not functioning normally. The wiring and control units
must be checked to locate the trouble. If the starter does not operate with the jumper attached, it will probably have to be removed from the engine
so it can be examined in detail.
CHECKING CIRCUIT WITH A VOLTMETER
Excessive resistance in the circuit between the battery and starter will reduce cranking performance. The resistance can be checked by using a
voltmeter to measure voltage drop in the circuits while the starter is operated. There are three checks to be made:
1. Voltage drop between vehicle frame and grounded battery terminal post (not cable clamp).
2. Voltage drop between vehicle frame and starting motor field frame.
3. Voltage drop between insulated battery terminal post and starting motor terminal stud (or the battery terminal stud of the solenoid).
Each of these should show no more than one-tenth (0.1) volt drop when the starting motor is cranking the engine. Do not use the starter for more
than 30 seconds at a time to avoid overheating it. If excessive voltage drop is found in any of these circuits, make correction by disconnecting the
cables, cleaning the connections carefully, and then reconnecting the cables firmly in place. A coating of petroleum jelly on the battery cables and
terminal clamps will retard corrosion.
On some models, extra long battery cables may be required due to the location of the battery and starter. This may result in somewhat higher
