PS Magazine - TB 43-PS-542
PS, The Preventative Maintenance Monthly
ISSUE 542
JANUARY 1998
M939-Series TRucks .±²
Dear Half-Mast,
When checking the air
FIlters on our unit's M939-
series trucks, we±ve found
some fouled with oil.
Where's the oil coming
from? And what should
we do about it?
Believe it or not.fouled filTers often sTarT wIth an overF±lled fuel tank²
³he fuel Rank, T´AnsmIssIon gear case and transfer gear case on These 5
-
tonners
all Vent into The air cleaner ducTµ
¶uel from an ove´·illed Tank can run through the vents ²¸² and end up in the gear
cases¹ ³henº oil from that ove»lled gear case is forced out through the vent
lines ¼²¸ and ends up In the air cleanerµ
Of course½ It's also possible thaT a leakIng interloCk air cylinder can pressurize
the Transfer and push oil inTo the air cleaner¾
So¿ ÀÁ the air resTrICtion
indiCator In The cab shows
red Check The aIr CleanerÃ
Äf It's oil-cloggedÅ check the
levels In The TÆansmIssIon
and Transfer gear casesÇ
Èf theyÉ re oÊerF±lled½ have
your meChanic d´AIn The excessË
Äf the Transfer or transmission gear Case is lowÌ support can Check the T´Ansfer
interlock aIr ÍylInder for lEaks²
Î good reminder not To oÊerFÏll The
fuel Tank Is to paInT a lIne two inches
from The Top of The tankÐ ³henÌ sTenCil
"ÑÎU³ÄON: Do noT FÏll aboÊe ThIÒ lIne
t
allow for eXpansIonÓ In ÄÔin black
lettersÕ as shoWn In
ÖIg
17
of
TB 43-0209.
PS5±²
JAN ³8
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