PS Magazine - TB 43-PS-436
PS, The Preventative Maintenance Monthly
ISSUE 436
MARCH 1989
M939/M939A 1-Series 5±Ton Trucks .²³
.±
´
µ¶·
²³
´µ-
¶·
l
rivers, the battery box is one place
where a stitch in time will head ofF
major repairs. Eyeball the battery box
once a week, lIe it says in the PMCS
in TM
¸¹2º20¹272»¼0½
LooK c±ose at th² RBber boots³ NSN
2¾º¿¹0À¹08¸¹4¸¸2,
on the battery
posts. ´F they're woµ, cut or missing,
get another set. ¶hey keep tHe meta± lid
Á
away ·om the posts and prevent sparks
that can ignite explosive batterY ¸mes.
The same battery Fumes come up into
the cab and attacks the seats i¹ some-
thing iº wrong. The culprit is usually
a c±ogged vent drain ho±e or a bad lid
sea±. Craw± under tHe trUck and ±ook
at tHe vent drain holes. C±ean »e¼ i¹
they»re covered wit½ ¾Ud¿ but doÀ'Á
just c±ean the outside Get a sticÃ, nai±,
or we±ding rod and puncH tHe dirt out
oF the vent Holes.
maR ÂÃ
The Äid sea± needs to be replaced iF
it»s toÅ or squashed oÆt oF shape so
that it doesn»t ÇrÈ a good, tight Fit.
Éeep an eye oÆt Çr corrosionÊ CorË
rosion builds up on batteries and
spreads to the battery box. Most times
it starts when a batterY is overFilled or
a ÌÍller cap is missing. Electrolyte is
maR ÂÃ
Ä
Flushed or s±oshed out and it tuµs to
a gray/white corrosion when it drÍes.
Electrolyte eats Æp cab±es, brackets
and gnaws holes in the battery boX
when it»s leFt alone. The Holes let su±Î
Corrosion builds up on bateR
and spreaDs To baTTeR box
ÏÆshed or s±oshed out and it Ðs to
a gray/white powder when it dries.
Call your mecHaÑic iF you see corroÒ
sion. Óour mecHanic can get rid oF it
with a solution oF baking soda and
water. Also, have the mech put Ôlt
washers, NSN
¾¸70Å0¼¹À0À¹4À47Æ
on
a±± battery ÕostsÊ THey cut down on
corrosion build up.
´t»s a good idea Çr your mechanic
to pÆll the batteries during semiannÆa±
service. That»s the only way to FÍnd
some rusty spots and pinholesÊ
Öusty spots need
×
to be sanded and
paintedØ Ùo±es are to be patched and
painted beÇre the batteries are pÆt
back in. Check the vent ho±es aFter the
box has been recoated or painted and
make sÆre they»re oÕen.
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