PS Magazine - TB 43-PS-682

PS, The Preventative Maintenance Monthly

ISSUE 682

SEPTEMBER 2009
PS Magazine - TB 43-PS-682 - Page 27 of 33
51
PS 682
SEP 09
•
Avoid idling the engine for longer than 5
minutes when possible. If you have to idle
for longer than 5 minutes, make sure the
engine rpms have stabilized before you do
the following steps to raise the idle speed
or increase engine rpms:
-
Set the parking brake
-
Start the vehicle in neutral
-
Press the cruise control button on
-
Press the resume/accel button repeatedly
until the tachometer reads 1,200 rpm
-
If needed, press the set/cruise button to
lower the engine’s rpms, or depress the
brake pedal to resume normal idle
•
Fuel and oil are not completely burned in the
combustion chambers, leaving carbon deposits
on the engine’s valve, resulting in burned valves
and bent push rods.
•
Condensation and unburned fuel—known as
blowby—gets past the pistons and into the
crankcase. That blowby in the crankcase mixes
with oil to make acid and sludge.
•
Engine oil breaks down. Poor lubrication burns
up bearings.
•
Sludge blocks lube passages. Oil can’t get
through to do its job, so heat and friction tear
up your engine.
MRAP MaxxPro Plus…
Avoid Long Engine Idle
here’s
what to
keep in mind
before
the day’s
run…
if your
vehicle’s
engine is
slobbering,
you’re
not
operating it
right.
after
the day’s
run, make sure
you idle the
engine for 4 to
5 minutes before
shutdown.
the engine needs
to cool down
slowly to avoid
cracking the
block, warping a
head or valves,
or baking the oil
till it’s not slick
enough to lube
the bearings.
there’s a one-liner
on warning page 2-1
of tm 9-2355-318-10
that says,
“do not idle
the vehicle for long
periods of time.”
but you might need reading glasses
to find it in the middle of the page!
you’re asking for
trouble when you
run the mrap’s
diesel engine for
long stretches at
low idle.
and there’s
more
trouble on the
horizon if you
continually start
the engine and shut it
down before it has a
chance to warm up.
it bears repeating–diesel
engines work best at normal
operating temperatures.
they run smoother
and longer.
a side effect
of incomplete
combustion is
“slobbering”
or “wet-
stacking.”
it looks
like black
sludge that
accumulates
around the
engine’s air
box drains
and exhaust.
what a
mess!
here’s what happens if you
don’t let the engine heat
up to normal operating
temperatures…
is this
really
necessary?
with all
that slobber
build-up? you
bet it is!
682.50-51.indd
1-2
8/3/09
3:04:25 PM
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