PS Magazine - TB 43-PS-570
PS, The Preventative Maintenance Monthly
ISSUE 570
MAY 2000
PS 570
10
MAY 00
ne thing you don’t expect to find
in the geared hubs on HMMWVs is
fuel. Gear oil? Of course. Water?
Maybe, if the hub seal is bad. But fuel?
It
is
possible, because the vent line
from the geared hub is connected to
the vent line from the fuel pump. But
for fuel to get into the geared hubs, the
fuel lift pump diaphragm must be leak-
ing. If the pump is leaking, your truck
could also be hard starting or rough
running.
Pump problems can cause fuel to be
pushed into the vent lines, and since
HMMWV . . .
the geared hubs are the lowest points
in the vent system, the fuel tends to go
there.
Fuel and gear oil together don’t lube
well, leading to damage to hub gears.
Plus, too much liquid in the geared
hubs leads to blown seals.
Remember, finding fuel in the geared
hubs is rare. But if you do, replace the
fuel lift pump, NSN 2910-01-168-
7905. Then replace the hub gear oil.
You need to blow out the vent system
with compressed air to get rid of the
fuel.
smell
that?
it's
fuel
in my
geared hub
!
how
did it get there?
could be the
vent line
.
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