TM 5-2420-230-24-2
B3.9 and B5.9 Series Engines
Turbocharger (010-033)
Section 10 - Air Intake System - Group 10
Page 10-29
Turbocharger (010-033)
General Information
Turbocharged Engines -- Exhaust Leaks
Inspect for exhaust leaks at the exhaust manifold, exhaust
pipe, and turbocharger gasket . Check for muffler or cata-
lyst restrictions. Leaks or restrictions will cause the turbine
and impeller to operate at a lower speed and reduce the
amount of air being forced into the cylinders. Again, the
symptom will be excessive smoke, low-manifold pressure,
and low power.
Lubricating Oil Consumption and Leaks
Engine lubricating oil is used to lubricate the bearings and
provide some cooling for the turbocharger. The lubricating
oil supplied to the turbocharger through the supply line is
at engine operating pressure. A return line connected to the
bottom of the turbocharger routes the lubricating oil back
to the engine lubricating oil pan.
Seal rings are used on each end of the rotor assembly. The
primary function of the seals is to prevent exhaust gases
and compressed air from entering the turbocharger hous-
ing. Lubricating oil leakage from the seals is rare, but it can
occur.
NOTE: Excessive crankcase pressure will not allow the oil
to drain from the turbocharger. This will load the bearing
housing and allow lubricating oil to leak past the compres-
sor seals and into the engine.
If turbine seal leakage into the exhaust occurs on engines
with a catalyst, check the exhaust restriction during the
repair.
A restricted or damaged lubricating oil return line will cause
the turbocharger housing to be pressurized, causing lu-
bricating oil to migrate past the seals.
L-1153
