STARTING SYSTEM

STARTER MOTOR BENCH TESTING AND REPAIR

Must wear overalls and steel cap work boots at all time when we doing testing and repair.

Equipments: starter motor, multimeter, armature grolwler, test light, sockets, screw drivers.

First we tested the starter motor on the test bench, carried out a no load test to see if the starter in good working condition. We mounted the starter onto the test bench, connected all wires, turn the machine on, voltmeter showed12.18V (spec >= 11V), clampmeter showed 38.8A (spec 30 to 50A), means the starter in good working condition.

Then disassenmbled the starter  by frollowing the sequence shown in our work book.

Next we visual inspected the armature, to see if there is any signs of overheating, burning, physical damage of poling, the one we were working on shows everything in good condition.

After that we use a multimeter in ohms range, put leads on commutator segments and armature core or shaft to check if they connect to each other, all readings shown infinity matched the specs.

Then put meter across each of the armature segments to check the continuity between all segments, meter was shown 0ohms, matched the factory specs.

Next measured the conmutator diameter and checked the mica undercut depth of the armature, our armature got 32mm in diameter and 1mm of mica undercut with in the factory specs.

After that we did the ground test and continuity test again by using the test light, to see if there is any short or open curcirt.

Once we finished the armature, we visual inspected the field coil and pole shoes, all in good condition.

Then we checked the continuity in the field windings by place the probles on each end of the field winding. We found the grounded winding shown infinite and not grounded winging shown 0ohms.

After that we measured the length of brushes, all four of them have good length of 15mm, and tested the brush holder, to see if two of them grounded and other two not shorted to ground.

Then we carried out a solenoid testing. First we tested the pull in winding by connecting 9V power supply to S and M terminals, the plunger been pulled in and current draw was shown 20A. Then tested the hold in winding by connecting 9V power supply to S terminal and solenoid body, the plunger remain in until we disconnect the power, and showed 8A current draw.

Last we checked pinion gear and one way clutch and brushes, they all in good condition.

Once we finished all the testing, we reassembled it back by reversing the proceduce we disassemble the starter and put it back onto the test bench, the starter motor running no problem and showing 13.2V voltage and 38A current.

From the bench testing and repair I understand when we servicing starter motor we need check if there is and wear and damage on the body before take it apart.
- A continuity test between the ends of field windings to check if there is any open circuit (reading needs less than 0.2ohms)
- A test for ground between end of filed windings and body to see if there is any shorted circuit (reading should be infinite).
- All segments on armature must be connected to each other in closed circuit (resistance between 0-1ohms) and not connect to any of the armature core of shaft (reading should be infinite).
- Commutator should be checked for wear segments (refer to SPEC).
- Brushes need in good length, and should be no continuity between insulated bursh holders and grounded brush holders.
- One way clutch and pinion gear should turn freely in running direction and in good condition.
- Solenoid needs to have a factory spec current draw to pull in the plunger and a factory spec current draw  to hold in the plunger.


STARTER MOTOR ON CAR TESTING

Equipments: vehicle with a pre-engage starter motor, multimeter, clamp meter.

We tested the starter motor on car to see how ti works. The motor that we tested from a Mazda 323, 1981-1985, with no transmission and not requires a power source for save its memory.

First we carried out some visual checks on the motor and meter, make sure everything in good condition.

Then we checked the battery OCV voltage 12.88V, means the battery in 100% charge. After that we checked the cranking voltage of the starter motor showed us 11.18V above of spec of 9.5V.

Next we performed voltage drop tests of different parts in starting system, battery positive terminal and solenoid input got 0.2V, solenoid input and output got 0.1V and battery negative and starter motor body got 0.2V, and calculated the total voltage drop in starting system was 0.5V within the sepc.

Last we tested the current draw of starter motor when it is cranking, meter showed us 128.7A, with in the spec of 125-175A.

From this test, I understand when the starter operate on car, it should spin at a good speed and the voltage drop of starter motor should not be less than 9.5V, the voltage drop of the whole circuit should be a maximum of 0.5V, and the current draw from the battery needs to be with in the factory spec.