NOTE: This content in this section is generic and may not apply to all available cooling fan drive belt systems.
The following section contains diagnostic information and procedures to aid in identifying drive belt and accessory
drive issues. These issues may include:
• Belt noise (squeal and chirp)
• Belt tracking Oumping)
• Belt fraying
• Snub breaks and punctures.
Common causes of drive belt noise, fraying and breaks are:
• Drive pulley misalignment
• Embedded debris in drive pulley grooves
• Incorrect belt material and/or belt length
• Damaged or incorrect automatic belt tensioner
• Improper drive belt routing
• Improper fan size and/or fan clutch.
The original drive belt and tensioner should be used if possible while troubleshooting drive belt issues. Replacement
of a belt and/or tensioner prior to troubleshooting may mask the root cause of the issue due to the break-in time
required for a belt and tensioner.
NOTE: A newly installed belt and/or tensioner will not come to rest properly until the engine is operated. Always
operate the engine for a brief period of time prior to verifying the tensioner resting location.
Inspect the automatic belt tensioner. Refer to Procedure 008-087 in Section 8. If the belt tensioner does not meet
the reuse criteria, the belt tensioner must be replaced.
With the belt installed, check the automatic belt tensioner resting position. If the belt tensioner arm stop is contacting either of the spring case stops:
• Verify the correct belt part number is installed
• If the correct belt is installed, replace the belt.
Verify all accessory drive components and pulleys are correct. Components yielding incorrect part numbers, or
installed without the appropriate spacers and/or brackets may contribute to gross drive belt misalignment.
Verify proper drive belt routing, if available. Refer to the OEM service manual.
Isolating the source of drive belt noise may be done by use of an electronic stethoscope, or an equivalent device
designed to block audible noise other than that desired by use of a microphone.
Drive belt noise may be difficult to isolate and troubleshoot. The origin of drive belt noise may not be located at the pulley out of alignment, rather ‘upstream’ from the noise origin.
Troubleshooting should always be completed in a direction opposite belt travel (i.e. counter clockwise) beginning at the pulley where the noise originates.
Arrow number (1} indicates belt travel direction, whereas arrow number (2} represents the direction in which troubleshooting should be conducted.
• Flat pulleys should be inspected for uneven wear patterns
• Grooved pulleys should be inspected for embedded debris, belt dust buildup, and pulley alignment.
NOTE: The belt alignment laser tool can identify misalignment of pulleys down to 1 12 of a belt rib. The capability of the alignment fixture is contingent upon proper calibration. Make sure all set-up and calibration procedures are followed before verifying pulley alignment.
Use a Belt Alignment Laser Tool, Part Number 3163524, or equivalent, to verify all pulleys are aligned correctly.
Pulley alignment should always be checked from the fan pulley and crankshaft pulley to other front end mounted
grooved pulleys. Contact a Cummins® Authorized Repair Location for drive belt alignment.
If a pulley is identified as out of alignment, verify the component mounting bracket installation.
Certain engines feature an automatic belt tensioner mounted to the water inlet connection. Verify the locating roll pins (1) are:
• Installed into the connection
• In contact with the cylinder block
• Do not appear to be bent or out of place.
If the water inlet connection and/or roll pins are not installed correctly, remount the water inlet connection.
Refer to Procedure 008-082 in Section 8.
Certain alternator mounting brackets are aligned to the cylinder head by roll pins. Verify the locating roll pins (1)
are:
• Installed into the alternator bracket
• In contact with the cylinder head
• Do not appear to be bent or out of place.
If the alternator bracket and/or roll pins are not installed correctly, remount the alternator bracket. Refer to
Procedure 013-003 in Section 13.
Check drive pulley alignment with the belt alignment laser tool, Part Number 3163524, or equivalent, after any
bracket adjustments are made.
Certain ‘pad mounted’ components which do not contain locating features can be positioned on the mounting
brackets for fine adjustments.
