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, 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, then perform the belt
tension inspection. To inspect a belt, gently twist the
belt to view the belt sidewalls and the underside of
the belt. When replacing a matched set of belts, al-
ways replace both belts at the same time. Matched
belts must be from the same manufacturer.
Visual Inspection
For examples of drive belt conditions, see
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 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
Business Class® M2 Workshop
Manual
.
Belt Tension Inspection
Engine drive belts on the Mercedes-Benz and Cater-
pillar engines have belt tensioners that automatically
adjust the tension on the belt. These belts do not
require adjustment.
Caterpillar 3126 Engine
Inspect the belt tensioner for unusual noise and ex-
cessive looseness or shaking of the pulley bearings.
See
Fig. 2
. If the belt tensioner requires disassem-
bly, refer to the engine service manual.
01–02 Engine Support Fastener
Checking
Front and rear engine supports for vehicles built from
January 2007 require no periodic maintenance.
Mounts should be inspected when the engine is re-
moved for service. For vehicles manufactured prior to
January 2007, perform the following check.
Engine
01
Business Class M2 Maintenance Manual, August 2015
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