b. Inspect the engine air cleaner element. Replace
a dirty engine air cleaner element with a clean
engine air cleaner element. Refer to Operation
and Maintenance Manual, “Engine Air Cleaner
Element (Dual Element) - Clean/Replace” or
Operation and Maintenance Manual, “Engine Air
Cleaner Element (Single Element) - Replace” for
the correct procedure. Inspect the engine air
cleaner service indicator. Refer to Operation
and Maintenance Manual, “Engine Air Cleaner
Service Indicator - Inspect” for the correct
procedure.
c. Inspect the engine crankcase breather. Clean
the engine crankcase breather or replace the
engine crankcase breather if the engine
crankcase breather is plugged.
d. Remove the pipe for the oil drain. Inspect the
drain opening. Inspect the oil drain line. Inspect
the area between the bearings of the rotating
assembly shaft. Look for oil sludge. Inspect the
oil drain hole for oil sludge. Inspect the oil drain
line for oil sludge in the drain line. If necessary,
clean the oil drain line. Replace the oil drain line
if there is any sign of damage to the oil drain
line.
e. Inspect the back pressure valve for visual
damage. Check that the exposed spring and
lever mechanism is free from mud and debris.
The operation of the back pressure valve can be
checked by turning the keyswitch to the RUN
position and then to the OFF position. This will
drive the back pressure valve to the CLOSED
position for approximately one second and
return the back pressure valve to the OPEN
position. This motion is visible from the exposed
spring and lever mechanism.
f. If steps 3.a through 3.e did not reveal the source
of the oil leakage, the turbocharger has internal
damage. Replace the turbocharger.
Inspection of the Turbine Wheel
and the Turbine Housing
Remove the air piping from the turbine housing.
1. Inspect the turbine for damage by a foreign object.
If there is damage, determine the source of the
foreign object. Replace the turbocharger. If there is
no damage, go to step 2.
2. Inspect the turbine wheel for the carbon and other
foreign material. Inspect turbine housing (1) for
carbon and foreign material. Replace the
turbocharger, if necessary. If there is no buildup of
carbon or foreign material, go to step 3.
3. Turn the rotating assembly by hand. While you turn
the assembly, push the assembly sideways. The
assembly should turn freely. The turbine wheel
should not rub turbine wheel housing (1). Replace
the turbocharger if turbine wheel rubs turbine
housing (1). If there is no rubbing or scraping, go
to step 4.
4. Inspect the turbine and turbine housing (1) for oil
leakage. Inspect the turbine and turbine housing
(1) for oil coking. Some oil coking may be cleaned.
Heavy oil coking may require replacement of the
turbocharger. If the oil is coming from the
turbocharger center housing go to step 4.a.
Otherwise go to “Inspection of the Wastegate”.
a. Remove the pipe for the oil drain. Inspect the
drain opening. Inspect the area between the
bearings of the rotating assembly shaft. Look for
oil sludge. Inspect the oil drain hole for oil
sludge. Inspect the oil drain line for oil sludge. If
necessary, clean the drain line.
b. If crankcase pressure is high, or if the oil drain is
restricted, pressure in the center housing may
be greater than the pressure of turbine housing
(1). Oil flow may be forced in the wrong direction
and the oil may not drain. Check the crankcase
pressure and correct any problems.
c. If the oil drain line is damaged, replace the oil
drain line.
d. Check the routing of the oil drain line. Eliminate
any sharp restrictive bends. Make sure that the
oil drain line is not too close to the engine
exhaust manifold.
e. If steps 4.a through 4.d did not reveal the source
of the oil leakage, turbocharger (3) has internal
damage. Replace the turbocharger.
Inspection of the Wastegate
The wastegate actuator controls the amount of
exhaust gas that is allowed to bypass the turbine side
of the turbocharger. This valve then controls the rpm
of the turbocharger.
When the engine operates in conditions of a low
boost (lug), a spring presses against a diaphragm in
the canister. The load on the spring holds the
wastegate closed. The turbocharger can then
operate at maximum performance.
When a boost pressure signal acts against the
diaphragm in the wastegate actuator, the pressure
overcomes the spring and the wastegate will open.
The rpm of the turbocharger becomes limited. The
rpm limitation occurs because a portion of the
exhaust gases bypass the turbine wheel of the
turbocharger.
90 UENR4490-01
Air Inlet and Exhaust System
This document has been printed from SPI2. NOT FOR RESALE
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