Engine Drive Belt
The engine belt drives the alternator
and the cooling fan. Check the engine
belt daily for any damage. The engine
drive belt must be replaced if the belt
appears frayed, punctured, badly
cracked or breaks. Belt damage can
be caused by:
Belt damage can be caused by:
• Incorrect tension.
• Incorrect size or length.
• Pulley misalignment.
• Incorrect installation.
• Severe operating environment.
• Oil or grease on the side of the belt.
Tensioner
Alternator
Crankshaft Pulley
Idler
Fan Pulley
Water
Pump
Idler
-OR-
(AC Compressor
OPTION)
Figure 5-10. Engine Belt
Engine must be turned off and the wheels blocked to prevent motion when servicing the
machine to prevent serious injury or death.
Inspect the drive belt for damage regularly. Inspect the
belt grooves for debris, uneven/excessive rib wear or
exposed belt cords. Inspect the back side of the belt
for glazing (high heat), debris or exposed belt cords.
Cracks across the width of the belt are acceptable,
but cracks along the length of the belt intersecting with
cracks across the width must be replaced.
To replace the belt:
1. Turn off engine and block the wheels to prevent
movement while working on the machine.
2. Using a 3/8-inch square drive, rotate tensioner
in the direction shown in Figure 5-10 to relieve
pressure on the belt. Remove the belt.
NOTE: The spring-loaded belt tensioner must be
pivoted away from the drive belt. Pivoting
in the wrong direction can damage the
tensioner.
3. Inspect the tensioner, idler and drive pulleys for dirt,
wear and cracks.
NOTE: Do not confuse build-up road dirt with wear.
Remove any debris from the grooves of the
pulleys, clean, check and reuse all pulleys
if not damaged rather than replacing. If
pulleys are damaged, replace before
4. Route the new drive belt as shown in Figure 5-10,
except over the water pump pulley.
5. Rotate tensioner in the direction shown in Figure
5-9, then nish installing the belt, routing the belt
over the water pump pulley LAST.
6. Slowly release the tensioner to apply tension to the
drive belt.
7. Check the alignment of the belt with the tensioner
and the rest of the front-end accessory drive.
8. Start the engine and listen for belt “squeal,”
which indicates belt slippage. If you hear the
belt squealing, recheck the routing to ensure it is
installed correctly on each pulley.
Check the engine belt tensioner, pulley and arm for
cracks every 500 hours. If either component shows
damage, register or log onto the Cummins engine
website for access to additional engine information:
https://quickserve.cummins.com/info/index.html
Maintenance
LeeBoy 685D Motor Grader5-14
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