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 can not drop. Failure to follow these steps
could result in serious personal injury or death.
01–01 Engine Drive Belt
Inspection
Worn or loose drive belts may cause engine over-
heating or loss of alternator power. Excessive ten-
sion, or too little tension on the belt may result in ex-
cessive and premature belt wear or accessory
bearing failure. Serpentine belts are retained by a
belt tensioner that requires no tension adjustment.
Replace the drive belt if any conditions described
below are found. To inspect a belt, gently twist it to
view the belt sidewalls and bottom.
IMPORTANT: For EPDM rubber drive belts, do
not rely on cracking as an indicator of belt wear.
EPDM rubber drive belts resist cracking better
than Neoprene belts. A better indicator of wear
on EPDM belts is material loss.
Belt and Pulley Inspection
1.
Inspect the belt for glazing. Glazing is repre-
sented by shiny sidewalls, and is caused by fric-
tion created when a loose belt slips in the pul-
leys. It can also be caused by oil or grease on
the pulleys.
2.
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.
3.
Check the belt for a jagged or streaked sidewall.
Jagged or streaked sidewalls are the result of
foreign objects, such as sand or gravel in the
pulley, or a rough pulley surface.
4.
Check for tensile breaks (breaks in the cord
body). Cuts in a belt are usually caused by for-
eign objects in the pulley, or by prying or forcing
the belt during removal or installation.
5.
Check for uneven ribs on serpentine belts. For-
eign objects in the pulley will erode the under-
cord ribs, causing the belt to lose its gripping
power.
6.
For EPDM belts, check the belt for material loss,
which causes the belt to seat further down in the
pulley and to ride directly on the pulley tips. See
Fig. 1
.
7.
For Neoprene belts, check the drive belts for
cracks. Small irregular cracks are usually signs
of an old belt.
8.
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, place a stetho-
scope on the component being checked, not the
pulley, to isolate the area from outside interfer-
ence.
9.
Inspect all pulleys for foreign objects, oil, or
grease in the grooves.
Belt Tensioner Inspection
On belts equipped with a spring tensioner, belt ten-
sion is automatically adjusted. Check that the ten-
sioner is holding tension on the belt by inserting the
end of a breaker bar in the 1/2-inch square hole on
the forward face of the tensioner, and rotating the
tensioner away from the belt. When the breaker bar
is slowly released, the tensioner should return to its
original position. The tensioner should rotate
smoothly with no binding. If not, see Group 01 of the
122SD and Coronado Workshop Manual for replace-
ment instructions.
Engine
01
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