Cleaning And Inspection; Testing - Mercury 40 Service Manual

4. Remove components from armature
d
a
b
a - Spacer
b - Spring
c - Drive Assembly
d - Drive End Cap
e - Armature Shaft
f - Washer

Cleaning and Inspection

Clean all motor parts.
1.
Check pinion teeth for chips, cracks or excessive
2.
wear.
Replace the drive clutch spring and/or collar, if
3.
tension is not adequate, or if wear is excessive.
Check that the brush holder is not damaged or is
4.
not holding the brushes against the commutator.
Replace brushes that are pitted or worn to less
5.
than 1/4 in. (6.4mm) in length. Refer to "Brush
Replacement", following.
Replace a damaged or excessively worn bushing
6.
in the end cap.
Check the armature conductor (commutator bar
7.
junction) for a firm connection. A poor connection
usually results in a burned commutator bar.
Re-surface and undercut a rough commutator, as
8.
follows:
CAUTION
Do not turn down the commutator excessively
Re-surface the commutator and undercut the
a.
insulation between the commutator bars 1/3
in. (8.5 mm) to the full width of the insulation,
make sure that the undercut is flat.
2B-16 - ELECTRICAL
.
f
e
c
.
Clean the commutator slots after undercut-
b.
ting.
De-burr the commutator lightly with No. 00
c.
sandpaper, then clean the commutator.
Check the armature on a growler for shorts.
d.
See "Testing", following.
Open-circuited armatures are repairable. The
9.
most likely place for an open circuit is at the com-
mutator bars. Long cranking periods overheat
the starter motor so that solder in the connections
melts. The poor connections cause arcing and
burning of the commutator bars.
Repair bars, that are not too badly burned, by re-
10.
soldering the leads in bars (using rosin flux sol-
der) and turning down the commutator in a lathe
to remove burned material, then undercut the
mica.
Clean out the copper or brush dust from slots be-
11.
tween the commutator bars.
Check the armature for shorts and ground. See
12.
"Testing", following
.

Testing

ARMATURE TEST FOR SHORTS
Check armature for short circuits by placing on growl-
er and holding hack saw blade over armature core
while armature is rotated. If saw blade vibrates, ar-
mature is shorted. Re-check after cleaning between
commutator bars. If saw blade still vibrates, replace
armature.
90-852572R1 JANUARY 1998