Thomas SAF-T-LINER C2, Руководство по обслуживанию

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01–00 Safety Precautions
Safety Precautions in this section apply to all
procedures within this group.
DANGER
When working on the vehicle, shut down the en-
gine or motor, set the parking brake, and chock
the tires. Before working under the vehicle, always
place jack stands under the frame rails to ensure
the vehicle cannot drop. Failure to follow these
steps could result in serious personal injury or
death.
01–01 Engine Drive Belt
Inspecting
Worn or loose drive belts may cause premature pul-
ley bearing failure or engine overheating. Too much
or too little tension on the belt may result in exces-
sive or premature belt wear. Replace the engine
drive belt if any conditions described under "Visual
Inspection" are found.
Visually inspect all drive belts. To inspect a belt, gen-
tly twist the belt to view the belt sidewalls and the
underside of the belt. When replacing a matched set
of belts, always replace both belts at the same time.
Matched belts must be from the same manufacturer.
Visual Inspection
For examples of drive belt conditions, see Fig. 1 .
1. Inspect the belt for glazing. Shiny sidewalls are
evidence of glazing, which is caused by friction
created when a loose belt slips in the pulleys. It
can also be caused by oil or grease contamina-
tion on the pulleys.
2. Check for tensile breaks or breaks in the cord
body. Cuts in a belt are usually caused by for-
eign material in the pulley or by prying or forcing
the belt during removal or installation.
3. Check the belt for ply separation. Oil, grease, or
belt dressing can cause the belt to fall apart in
layers. Repair any oil or coolant leaks that are
affecting the belts before replacing the drive
belts. Do not use belt dressing on any belt.
4. Check for uneven ribs on serpentine (poly-V)
belts. Foreign material in the pulley will erode the
undercord ribs causing the belt to lose its grip-
ping power.
5. Check the belt for a jagged or streaked sidewall.
Jagged or streaked sidewalls are the result of
foreign material, such as sand or gravel, in the
pulley, or a rough pulley surface.
6. Check the drive belts for cracks. Small, irregular
cracks are usually an indication of an old belt.
7. Visually inspect the pulleys for excessive play or
wobble. Excessive play or wobble indicates a
failure of the pulley bearing. Check for belt
squealing or squeaking. Replace the bearings as
necessary.
NOTE: If it is difficult to distinguish the location
of a supposed bearing noise, obtain a stetho-
scope and place it on the component being
checked, not the pulley, to isolate the area from
outside interference.
8. Inspect all pulleys for foreign material, oil, or
grease in the grooves.
If the engine drive belt needs to be replaced, see
Group 01 of the Saf-T-Liner C2 School Bus
Workshop Manual , or take the vehicle to an au-
thorized Freightliner dealer.
Belt Tension Inspection
Drive belts on Mercedes-Benz engines have belt ten-
sioners that automatically adjust the tension on the
belt. These belts do not require adjustment.
Cummins Engines
Inspect the belt tensioner for unusual noise and ex-
cessive looseness or shaking of the pulley bearings.
If the belt tensioner requires disassembly, refer to the
engine service manual.
01–02 Engine Support Fastener
Checking
1. Check the engine support fasteners at the rear of
the engine for tightness. Tighten the fasteners
241 lbf·ft (327 N·m).
Engine
01
Saf-T-Liner C2 School Bus Maintenance Manual, June 2015
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