TM 5-3805-280-24-2
Air Intake and Exhaust System
30
buildup of sludged oil, or high crankcase pressure,
INGESTION OF FOREIGN OBJECTS
4
which can be due to restricted crankcase breather or
excessive engine blowby.
The third cause of turbocharger damage is the
ingestion of foreign objects. Foreign objects or
Periodically check both the turbocharger oil drain tube
particles can be ingested and cause damage to the
and engine breather tube for damage or restriction.
turbocharger on both compressor and turbine sides.
Correction of these conditions leads to longer
This is easy to avoid.
turbocharger life.
On the compressor side, foreign objects usually take
ABNORMALLY HIGH EXHAUST TEMPERATURES
the form of dust, sand, or shreds of air cleaner
element that enter through improperly installed air
A fifth cause of turbocharger damage is abnormally
cleaner elements. Leaky air inlet piping (loose clamps
high exhaust temperatures. Elevated exhaust
or torn rubber joints) or torn pleats in dry-type air
temperatures cause coking of oil which can lead to
cleaner elements also create problems.
bearing failure. Extreme over-temperature operation
can case wheel burst.
The result is erosion of compressor blades that can
cause the delicately balanced wheel to wobble.
There are two basic causes of over-temperature. The
first is restricted air flow and the second is
IMPORTANT: Whenever an internal engine failure
overpowering the engine. In either case the engine has
(valve, valve seat, piston) occurs, a
more fuel than available air for proper combustion, this
thorough inspection of the
overfueled condition leads to elevated exhaust
turbocharger MUST BE performed
temperatures.
before returning engine to service.
Causes of restricted air flow can include damaged inlet
RESTRICTED OIL DRAINAGE
piping, clogged air filters, excessive exhaust restriction,
or operation at extreme altitudes. Overpowering
A fourth cause of turbocharger damage is restricted
generally is due to improper fuel delivery or injection
lube oil drainage. The lubricating oil carries away heat
timing. If overtemperature operation has been
identified, an inspection of the air inlet and exhaust
exhaust gases. If drainage back to the sump is
systems should be performed. Also, check the fuel
impeded, the bearings will overheat with damage that
delivery and timing.
will ultimately lead to failure.
There are two primary reasons for restricted drainage.
A blocked drain tube, due to either damage or a
RG,30,JW7583
1920NOV972/2
13-360
