Starter motor bench testing and repair

Connecting & what Ground testing a windings tell us:

With the meter set on 2K and one lead connected to any end of the widing and the other to a given earth point as depicted in diagram below

The reading must read infinity this means that there is no circuit between the winding and ground ( earth)

Any other reading means that the winding has shorted to earth.

If it has shorted to earth the winding either needs to be replaced or rewound.
————————————————————————————————————————
Connections & result of internal circuit resistance testing windings:

With the meter set on 200Ω connect the 2 probes together and get the internal resistance of the meter and leads for example 0.2Ω. This reading will need to be taken away from the actual reading to give you the true resistance value of the winding.

Connect on probe to one end of the winding and the other to the other end as depicted in the diagram below.

The reading in the diagram above is 3.8Ω but it isn't the true resistance. The internal resistance for example of 0.2Ω must be taken away giving a result of 3.6Ω. This is the true resistance and must be within the manufacturer specification.

There are four possible result that you  can get when doing an internal winding resistance test, they are:

Within specification

Open circuit

Lower resistance than Spec

Higher resistance than Spec

Within specification means that the winding has past this test and can be used again.

An open circuit result means there is break in the winding. This requires that the winding is either replaced or rewound; breaks in winding are very rarely repaired. Refer to the diagram below.

Lowe than specified resistance indicates an internal short result. This means that there is break in the insulation of the winding, it hasn't shorted to ground but has shorted to another part of the winding as illustrated in the diagram below.

This allows the current to take a shorter path through the winding effectively lowering the resistance below Manufacturers specifications

This requires that the winding is either replaced or rewound.

Higher than specified resistance can indicate poor winding connection. This could mean there is dirt or corrosion where the winding ends are connected, thus causes a higher than normal resistance.

Poor connections at the ends of the winding may be able to be repaired by removing them and cleaning up the connection points and re-soldering as necessary

Will be given another starter motor and it should also be tested before dismantling.
————————————————————————————————————————
No Load Test:
Mount the starter in a test bench, carry out no load test then enter your meter readings in the chart below.

NO LOAD TEST          MANUFACTURERS SPECIFICATIONS          NO LOAD TEST RESULT
Voltage                          No less than 11volts                                              11.70V
Current                          30 to 50 Amps                                                      37.6A

Label the components:

A. Commutator

B. Roller-type/ overruning clutch

C. Brush spring/ Carbon brush.

————————————————————————————————————————

Disassembly:

Disassemble the starter in the correct sequence as demonstrated by your lecturer. Failure to follow the correct sequence and procedures may result in damage to the starter motor.

Sequence:

1. Scribe alignment marks along the two end housings and field housing (main body) of the starter motor, this will help to align the major compinents.

2. Remove M terminal wire from the solenoid ( this wire connects the output from the solenoid to the starter motor)

3. Scribe alignment marks on the solenoid body and mounting then remove solenoid

4. Remove any screws in the commutator end housing ( failure to do this can result in major damage to the brushes or field windings).

5. Remove commutator end housing

6. Remove brushes as necessary to remove brush plate assembly

7. Remove field coil housing ( main body of the starter motor)

8. Remove shift fork from drive end housing ( it is important that you mark the position of the shift fork)

9. Remove the armature assembly

10. Remove the overruning clutch from the shaft ( clean any burrs with emery paper for easy removal of the clutch)

————————————————————————————————————————

Testing Armature

Visual Inspection:

Visual Inspection- Check for signs of:

Overheating

Burning

Physical damage of insulation and coil windings

Poling

COMPONENT TEST REPORT

ARMATURE     MANUFACTURER'S SPECIFICATIONS     TEST RESULTS          SERVICEABLE

Overheating        Visual Inspection                                          No signs of overheating     No

Burning               Visual Inspection                                          No signs of burning           No

Physical damage  Visual Inspection                                         The insulation was

                                                                                              damaged onto the poling   Yes

Poling                 Visual Inspection                                          The poling has been

                                                                                              damaged by the insulation Yes

————————————————————————————————————————

Ground Circuit Tests:

Use a multi-meter in the ohms range and check for:

Ground Short circuit between each of the commutator segments and the amature core or shaft

ARMATURE GROUND TEST

MANUFACTURER'S SPECIFICATIONS          TEST RESULTS          SERVICEABLE

Infinity                                                                    infinity                            Yes

————————————————————————————————————————

Continuity Circuit Test

With the ohmmeter in the same range check continuity between one of the commutator segments while moving the second probe around on each of the other commutator segments.

ARMATURE CONTINUITY TEST

MANUFACTURER'S SPECIFICATIONS          TEST RESULTS          SERVICEABLE

0-1Ω                                                                     0Ω                                Yes

————————————————————————————————————————

Testing Commutator:

Measure the Commutator diameter and check the mica undercut depth as necessary.

COMMUTATOR TEST

MANUFACTURER'S SPECIFICATIONS          TEST RESULTS          SERVICEABLE

Minimum diameter 28.8~31mm                              31.5mm                        Yes

Mica Undercut 0.7~1.0mm                                    0.7mm                           Yes

————————————————————————————————————————

Check Armature Shaft for run out:

To check for run-out, place the armature between the "v" blocks.

Turn the armature 360° while reading the dial test indicator set up on the armature core as indicated by the arrow

ARMATURE RUNOUT TEST

MANUFACTURER'S SPECIFICATIONS          TEST RESULT           SERVICEABLE

0~0.2mm                                                               0.05mm                       Yes

————————————————————————————————————————

Alternative Method of Testing Armature

Using 48 volt test Light

Continuity test keep one of the probes on one segment and move the other probe around each of the other segments. ( This test applies greater pressure to the windings and should be used where available) The test light should glow.

Ground test place one probe on any commutator segment and the other on either the armature core or shaft. The test light should not glow.

ARMATURE CONTINUITY AND GROUND TEST

MANUFACTURER'S SPECIFICATIONS          TEST RESULT          SERVICEABLE

Continuity Test Light on over each segment            Yes,The light on.          YES

                                                                             The commutater

                                                                             segment are connected

Ground Test Light Off                                            Yes,The light off          YES

                                                                              The commutater

                                                                              segment aren't

                                                                              connceted the armature

                                                                              cove

————————————————————————————————————————

Testing for internal short circuit using growler:

1. Place the armature on the "V" of the growler.

2. Turn the switch on to Growler position.

3. Hold a hacksaw blade or metal strip along the armature and rotate the armature.

ARMATURE INTERNAL SHORT TEST

MANUFACTURER'S SPECIFICATIONS          TEST RESULTS          SERVICEABLE

Hacksaw blade will vibrate when placed over         Hacksaw which means          YES

shorted winding indicating a shorted armature         shorted winding indicating

                                                                             a shorted armature 

————————————————————————————————————————

Field Coil and Pole Shoes

Visual Inspection- Check for signs of:

Overheating

Burning

Physical damage of insulation and coil windings

Poling

COMPONENT TEST REPORT

FIELD COILS AND             MANUFACTURER'S             TEST RESULTS             SERVICEABLE

POLE SHOES                         SPECIFICATIONS

Overheating                           Visual Inspection                       No signs                          YES

Burning                                  Visual Inspection                       No signs                          YES

Physical damage                    Visual Inspection                       There was a damage         No

                                                                                              for the field coil                      

Poling                                    Visual Inspection                       The field coil has some      YES,can be fixed 

                                                                                              damage                  

————————————————————————————————————————

Test the Field coils for Continuity:

Checking for continuity in the field winding place the probes on each end of the field winding

Depending on the design of starter motor circuit, field winding maybe ground or insulated from the field housing.

COMPONENT TEST REPORT

FIELD COILS          MANUFACTURER'S          TEST RESULTS          SERVICEABLE

CONTINUITY         SPECIFICATIONS

If Grounded               TEST N/A                            N/A                              N/A

Not Grounded           0~0.02Ω                              0Ω                                YES

————————————————————————————————————————

Test the Field coils for grounding:

Ifthe field winding to ground test can be preformed ( the field winding is not attached to the body of the starter motor). Place the positive probe on the field wire or brush, then the common probe on the body of the starter. The meter should read Infinity.

COMPONENT TEST REPORT

FIELD COILS          MANUFACTURER'S          TEST RESULTS          SERVICEABLE

GROUNDING         SPECIFICATIONS

If Grounded              0~0.02Ω                               N/A                               N/A

Not Grounded          Infinity                                   Infinity                            YES

————————————————————————————————————————

Brushes:

Measure the length of the brushes and inspect for cracks and other damage.

Brushes sometimes have a scribed line on one face or refer to specification sheet for allowable length.

Note: When considering the brushes for replacement, remember that the starter may not be removed from a vechicle for over 100,000Km's. If the brushes are close to the minimum you should replace. New brushes are about 14mm long.

COMPONENT TEST REPORT

BRUSHES               MANUFACTURER'S               TEST RESULTS               SERVICEABLE

                                SPECIFICATIONS

MINIMUM             5mm                                          15.9/15.9/15.9/-                 YES

LENGTH

————————————————————————————————————————

Brush Holder Assembly

To check for short circuit between insulated brushes and holder set the Ohms meter on the lowest resistance. Place one of the probes on the brush and the other on the metal retaining plate.

COMPONENT TEST REPORT

BRUSH HOLDER          MANUFACTURER'S          TEST RESULTS          SERVICEABLE

ASSEMBLY                  SPECIFICATIONS

Grounded Holder            0~0.02Ω                               0.1Ω                             No

Insulated Holder              Infinity                                   Infinity                           YES

————————————————————————————————————————

Solenoid Magnetic Switch:

Identify terminals: "B" Battery Supply, "S" ignition/ starter switch supply and "M" starter motor supply.

Note: M terminal will have a wire going into the solenoid switch

Pull in winding Test:

connect 9V power supply between S and M terminals

Note this test is done with reduced voltage and for a maximum of 5 seconds to prevent heat damage to the winding

COMPONENT TEST REPORT

PULL IN WINDING          MANUFACTURER'S          TEST RESULTS          SERVICEABLE

                                           SPECIFICATIONS

Current Draw                      8~12Amps                            9.1A                              YES

Physical Action                   The Plunger should pull in       The plunger pull in           YES

————————————————————————————————————————

Hold in Test

Connect 9V power supply between S and solenoid body

Note this test is done with reduced voltage and a maximum of 5 seconds to prevent heat damage to the winding

Push the plunger in by hand and then release it.

COMPONENT TEST REPORT

HOLD IN WINDING          MANUFACTURER'S          TEST RESULTS          SERVICEABLE

                                            SPECIFICATIONS

Current Draw                       5~8Amps                               10.9A                           No

Physical Action                     The Plunger should                 The plunger was            YES

                                             remain in.                               still inside

                                            When the power is                 When the power is      

                                            disconnected the plunger        disconnected the

                                            should release.                       plunger shoot out

————————————————————————————————————————

Pinion gear and Overruning or one way clutch:

Check pinion for gear damage and smooth movement along the armature shaft.

Turn the pinion gear in the direction of motor rotation, the clutch should free wheel and against direct of rotation it should lock.

Brushes:

To check bushes for wear, insert the end of the armature shaft into the appropriate end housing bush to and assess the shaft to bush clearance.

COMPONENT TEST REPORT

DRIVE          MANUFACTURER'S          TEST RESULTS          SERVICEABLE

                     SPECIFICATIONS

Pinion Gear   Visual Inspection                   The pinion gear is good   YES

Bushes          Visual Inspection                   Bushes was damaged      NO

Clutch           Visual Inspection                   Clytch was good             YES

————————————————————————————————————————

Assembly:

Re-assemble the Starter Motor:

1. Lubricate the bushes.

2. Assembly in the reverse order of dismantling.

3. Note: Align marks when assembling the shift fork and the two end housings to the field body

4. Hold the brush springs back with a steel wire in the form of book. This will enable brush to be slid on the commutator

5. Do not over tighten any through bolts and screws.

Armature Thrust Clearance:

Check Armature Thrust Clearance. Check the Clearance with seal, spring and lock plate in place.

Pinion to Collar Clearance:

Mount the starter on the  testing machine. Connect power only to S terminal. This will move the pinion out towards the collar without armature turning.

————————————————————————————————————————

Final no load test:

Mount the starter in a test bench, carry out no load test then enter your meter readings in the chart below.

NO LOAD TEST          MANUFACTURER'S          NO LOAD TEST RESULTS

                                     SPECIFICATIONS

Voltage                         No less than 11 volts               11.47V

Current                         30~50Amps                            46.7A

Dose the starter motor run within manufacturers specifications YES

————————————————————————————————————————

The no load test is good, no any problems. In testing armature, we had some physical problems with the insulation, that was damaged onto the field coil cover. In the ground circuit test, it was gread, no problems and no damages. The alternative method of testing armature also looks good, field coil and pole shoes testing we have same problem as the testing armature, it's about the field coil cover. We broken the brushes when we was doing the brushes test, but we fixed that finaly.