normal operation.
This simple test will
bent blade can throw the rotating assem-
allow some positive testing on each en-
bly out of balance and shorten the life of
g i n e in all cases.
the turbocharger.
Turbocharger compressor end shaft oil
Inspect the oil inlet and oil return lines
seal effectiveness can be determined by
to make certain all of the connections are
the following procedure:
tight and that the lines are not dented or
looped so that oil flow to and from the
1. Determine that air inlet restriction is
Looping
center housing i s r e s t r i c t e d .
within the Detroit Diesel maximum limit.
the oil return lines disrupts gravity flow
R e f e r to Subsection 11A.
o f the oil back to the engine.
2. Be certain that the turbocharger oil
NOTE
drain line is unrestricted.
B e sure the oil inlet lines are filled
3. Be certain that the turbocharger has
with oil and that they are clear of
not obviously been damaged and in need
the turbine housings.
of major repair.
4. Remove the air intake ducting. In-
Check for signs of oil leaking from the
spect inside of the ducting for evidence
turbocharger housings.
If oil is found in the intake sys-
of oil.
tem, d e t e r m i n e t h e s o u r c e b e f o r e p r o -
Lubricant applied under pressure to the
ceeding with the compressor seal test
center housing while the shaft is not
and also thoroughly remove oil from the
turning may allow oil to enter the turbine
i n t a k e . Some external sources of oil are
and compressor housings. However, af-
a leak near an oil source as an engine
ter the turbocharger has been operated
breather, etc.
for a time under load conditions and with
the inlet restriction at normal, oil in
5. Remove the compressor housing from
If the
these sections should disappear.
the turbocharger.
oil does not disappear, refer to Chart 2
of Figure 11D-29 on page 11D-21.
6. Thoroughly clean the internal sur-
faces of the compressor housing, impeller
Evidence of oil in the inlet or outlet
cavity behind the impeller, and the
ducts or dripping from either housing
backplate annulus with suitable solvent
indicates a seal problem that will require
spray and then dry completely with shop
Refer to
overhaul of the turbocharger.
air.
Chart 3.
7. Spray the backplate annulus with a
Tests show there are three conditions
light coating of "Spot-Check" developer
that contribute to oil seal leakage at the
type SKD-MF, or equivalent.
internal turbocharger oil seal.
8. Install the compressor housing on the
1. A worn or defective oil seal, which
turbocharger and reconnect the inlet and
must be replaced.
outlet connections.
2. High air inlet restriction (above speci-
9. Warm up the engine to normal operat-
This will cause oil to be
fied limits).
ing temperature.
pulled past the oil seal.
10. Operate the engine at no load at the
3. Long periods of operation where the
governor limited high speed for approxi-
engine is being motored (using the en-
mately five minutes.
gine as a braking device.). This can al-
s o cause oil to pass by the oil seal.
11. Return the engine to low idle and
then stop it.
To confirm oil leakage from one or more
of these conditions, remove the compres-
12. Remove the intake duct and outlet
sor housing and inspect the backplate.
hose and then remove the compressor
If the surface is wet with oil, it indicates
housing.
Evidence of compressor end
leakage.
s h a f t seal oil leakage will be observed as
oil
streaks
in
the
"Spot-Check"
develop-
If this test does not show leakage pat-
on t h e b a c k p l a t e a n n u l u s .
This
er
terns, the oil seal assembly is good for
11D-22
