speeds up to 75,000 rpm. Therefore, it is of
utmost importance that turbochargers be main-
tained in proper working order at all times. If a
turbocharger is allowed to operate without
lubrication, cooling, or the proper clearances, it
not only could be completely destroyed in a
matter of minutes but also could possibly cause
extensive damage to other machinery and
personnel.
All oil lines and air duct connections should
be inspected and free of leakage. The air filter
should be clean and in place and there should be
no build-up of dust or dirt on the impeller. Turn
the impeller by hand and check for binding or rub-
bing and listen for any unusual noises.
When the turbocharger is operating, listen for
any unusual noise or vibrations. If you hear a
shrill high pitch whine, shut down the engine at
once. The whine may be caused by a failing
bearing, and serious damage may result. Do not
confuse the whine heard as the turbine runs down
with that of a bad bearing.
Noise from the turbocharger may also be
caused by improper clearances between the
turbine wheel and the turbine housing. The
clearances should be checked at predetermined in-
tervals in accordance with the PMS. Check
bearing axial end play and shaft radial movement.
Crankcase vents should not be directed towards
the turbocharger air intakes, as the corrosive gases
may cause pitting of the blades and bearings,
thereby reducing the life of the turbocharger.
Chapter 3—ENGINE MAINTENANCE
3-41
