TM 5-3805-281-24-2
Air Intake and Exhaust System
EXTENDING TURBOCHARGER LIFE
The easiest way to damage a turbocharger is through
Turbochargers are designed to last the life of the
improper start-up and shutdown procedures. Always
engine, but, because they operate at such high speeds
idle the engine for at least 30 seconds (no load) after
(100,000 rpm or more); a moment's carelessness can
start-up and before shutdown. Warming the engine up
cause them to fail in seconds.
before applying a load allows oil pressure to build up
and lines to fill with oil.
The major causes of turbocharger failures are:
Lack of Lube Oil (Quick Starts and Hot
Idling the engine before shutdown allows the engine
and turbocharger to cool. "Hot" shutdowns can cause
Shutdowns)
Oil Contamination
the turbocharger to fail because after high-speed
Ingestion of Foreign Objects
operation the turbocharger will continue to rotate long
Restricted Oil Drainage
after the engine has been shut off and oil pressure has
Low Oil Level
dropped to zero. This will cause heat to build up and
Operation on Excessive Side Slopes
possibly damage bearing. It can also cause carbon
Abnormally High Exhaust Temperatures
and varnish deposits to form.
OIL CONTAMINATION
LACK OF LUBE OIL
A second cause of turbocharger failures is
Oil not only lubricates the turbocharger's spinning shaft
contaminated oil. It can be caused by a worn or
and bearings, it also carries away heat. When oil flow
damaged oil filter or not changing the lube oil at
stops or is reduced, heat is immediately transferred
recommended intervals. Expecting the oil filter to
from the hot turbine wheel to the bearings, which are
remove dirt, sand, metal chips, etc. from the oil before
they reach the engine or turbocharger can be a costly
to the lack of oil. This combination causes the
mistake because contaminated oil may completely
turbocharger shaft temperature to increase rapidly.
bypass the engine oil filter if the oil filter or oil cooler is
clogged, if the filter element is improperly installed, or
If oil flow does not increase and the process continues,
if the oil is thick during cold weather.
bearings will fail. Once the bearings fail (which can
happen in just seconds) seals, shaft, turbine and
Four good ways of avoiding oil contamination are:
compressor wheels can also be damaged.
Always inspect the engine thoroughly during major
The principle causes of turbocharger bearing
overhaul. Look especially for any sludge or debris left
lubrication problems are low oil pressure, a bent,
in lube oil galleries.
plugged or undersized oil lube supply line, plugged or
restricted oil galleries in the turbocharger, or improper
Change lube oil at recommended intervals. Analysis of
machine start-up and shutdown procedure.
oil samples at filter change periods can help identify
potentially harmful contaminants in the oil.
Oil levels and pressure should always be closely
monitored and all worn hoses and lines should be
Clean the area around the oil fill cap before adding oil.
replaced. The turbocharger oil supply line should be
checked frequently to make sure it is not kinked or
Use a clean container when adding oil.
bent and it should always be replaced with a line of
equal size, length and strength.
Continued on next page
RG,RG34710,1256
1923OCT971/2
