Starter Spins But Does Not Rotate Flywheel; Starter Will Not Disengage When Start Switch Is Released; Loud Grinding Noises When Starter Runs; Starter Solenoid Resistance Tests - Yanmar 1GM10 Shop Manual

TROUBLESHOOTING
Ammeter
Starter motor
open circuit or a loose connection. If the engine does not
start, replace the starter solenoid.
Starter spins but does not rotateflywheel
2. Check the starter pinion gear. If the teeth are chipped
or worn, inspect the flywheel ring gear for the same prob-
lem. Replace the starter and/or ring gear as required.
3. If the pinion gear is in good condition, disassemble the
starter and check the armature shaft for corrosion. See
Brush Replacement, Chapter Nine, for the disassembly
procedure. If no corrosion is found, the starter drive mech-
anism is slipping. Replace the starter with a new or rebuilt
marine unit.

Starter will not disengage when start switch is released

This problem is usually caused by a sticking solenoid or
defective start switch, but the pinion may jam on the fly-
wheel ring gear on an engine with many hours of opera-
tion.
NOTE
A low battery or loose or corroded battery
connections can also cause the starter to re-
main engaged with the flywheel ring gear:
Low voltage at the starter can cause the
contacts inside the solenoid to chatter and
weld together; resulting in the solenoid
sticking in the ONposition.

Loud grinding noises when starter runs

This can be caused by improper meshing of the starter
Voltmeter
pinion and flywheel ring gear or by a broken overrunning
clutch mechanism.
1. Remove the starter. See Chapter Nine.
2. Check the starter pinion gear. If the teeth are chipped
or worn, inspect the flywheel ring gear for the same prob-
lem. Replace the starter andlor ring gear as required.
3. If the pinion gear is in good condition, the overrunning
clutch mechanism in the starter may be defective. Replace
the starter with a new or rebuilt marine unit.

Starter Solenoid Resistance Tests

Check the starter solenoid using the following resis-
tance tests:
,
1. Refer to Figure 2 and connect an ohmmeter lead to the
S terminal of the solenoid. Connect the remaining ohm-
meter lead to the metal body of the solenoid. The ohmme-
ter should indicate approximately one ohm or less.
Replace the solenoid if the ohmmeter indicates infinite re-
sistance (no continuity).
2. Refer to Figure 3 and connect an ohmmeter lead to the
S terminal of the solenoid. Connect the remaining ohm-
meter lead to the M terminal of the solenoid. The ohmme-
ter should indicate approximately one ohm or less.
Replace the solenoid if the ohmmeter indicates infinite re-
sistance (no continuity).
Starter Motor No-Load Current Draw Test
If troubleshooting indicates that the starter motor may
be defective, use the following starter motor no-load cur-
rent draw test to determine if the starter motor is in accept-
able operating condition.
To perform the test, the following equipment is needed:
an ammeter capable of measuring 0-1 00 amps, a voltme-
ter, a vibration tachometer and a fully charged 12-volt bat-
tery. Minimum battery capacity is 70 amp-hours for one-
and two-cylinder engines and 100 amp-hours for
three-cylinder engines.
fasten the motor in a vise or other suitable holding fixture.
2. Using a heavy gauge jumper cable, connect the amme-
ter in series with the positive battery terminal (Figure 4).
Connect a voltmeter to the battery.
CA UTION
Disconnect the negutive battery cable be-
fore performing resistance tests.
2 9