ISC, ISCe, QSC8.3, ISL, ISLe3, ISLe4 and QSL9 Engines – 008-002   Drive Belt, Cooling Fan

General Information

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Due to the number of drive belt arrangements, this procedure does not cover all available cooling fan drive belt routing.

To make sure the cooling fan drive belt is routed correctly upon installation, make a diagram of the cooling fan belt routing prior to removing the belt, as shown in the illustration.

The cooling fan belt routing typically consists of the following components, but may not include all of them:

  1. Crankshaft pulley/vibration damper
  2. Fan pulley
  3. Water pump pulley
  4. Refrigerant compressor pulley
  5. Alternator pulley
  6. Belt tensioner pulley.

NOTE: Some engine-driven belts are installed/supplied by the vehicle original equipment manufacturer (OEM). See the OEM service manual for removal and installation instructions.

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Troubleshooting

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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 (jumping)
  • 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 008-080 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.

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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.

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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.

 
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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.

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NOTE: The belt alignment laser tool can identify misalignment of pulleys down to ½ 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.

 
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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.

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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.

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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.

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Preparatory Steps

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 WARNING 

Batteries can emit explosive gases. To reduce the possibility of personal injury, always ventilate the compartment before servicing the batteries. To reduce the possibility of arcing, remove the negative (-) battery cable first and attach the negative (-) battery cable last.

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Remove

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 CAUTION 

The belt tensioner is spring-loaded and must be pivoted away from the drive belt. Pivoting in the wrong direction can result in damage to the belt tensioner.
 CAUTION 

Applying excessive force in the opposite direction of windup or after the tensioner has been wound up to the positive stop can cause the tensioner arm to crack or break
 CAUTION 

Using a socket extension is not recommended because it can cause axial twisting damage to the belt tensioner.

Lift the tensioner to remove the drive belt.

NOTE: If a socket extension is necessary, support the head of the ratchet with one hand to prevent the belt tensioner arm from unintended loading.

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Clean and Inspect for Reuse

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Inspect the drive belt for damage.

Transverse (across the belt) cracks are acceptable.

Longitudinal (direction of belt ribs) cracks that intersect with transverse cracks are not acceptable.

If the belt is frayed, punctured, or material is missing, the belt is unacceptable for reuse and must be replaced.

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Inspect the belt grooves for:

  • Embedded debris
  • Uneven/excessive rib wear
  • Exposed belt cords.

Inspect the backside of the belt for:

  • Glazing (high heat)
  • Uneven/excessive rib wear
  • Exposed belt cords.

If any of the above conditions are present, the belt is unacceptable for reuse and must be replaced.

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Inspect the idler and drive pulleys for wear or cracks..

Plastic pulleys often have a buildup of road dirt and belt material that is not to be confused with wear.

The dirt can be removed with a suitable tool to check for wear.

Clean, check, and reuse all pulleys in the front end accessory drive if not damaged, rather than replacing. Pulleys damaged from embedded debris MUST be replaced.

Inspect the tensioner. Refer to Procedure 008-080 in Section 8.

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Inspect all system pulleys for embedded debris:

  • Rocks, stones
  • Metal
  • Belt material.

Remove any debris from the grooves of the pulley. If the pulley has been deformed as a result of foreign material embedment, the pulley MUST be replaced.

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Inspect the drive belt pulleys and idlers for cracked or broken grooves.

Reference the following procedures if a pulley or idler is damaged:

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Install

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Route the drive belt on the engine. Use the belt diagram created in the Remove section. Do not install the belt over the water pump pulley at this time.

 
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 CAUTION 

The belt tensioner is spring-loaded and must be pivoted away from the drive belt. Pivoting in the wrong direction can result in damage to the belt tensioner.
 CAUTION 

Applying excessive force in the opposite direction of windup or after the tensioner has been wound up to the positive stop can cause the tensioner arm to crack or break.
 CAUTION 

Using a socket extension is not recommended because it can cause axial twisting damage to the belt tensioner.

Pivot the tensioner in the direction of the spring tang and install the drive belt, slipping the belt over the water pump pulley last.

Slowly, release the belt tensioner to apply tension to the drive belt.

NOTE: If a socket extension is necessary, support the head of the ratchet with one hand to prevent the belt tensioner arm from unintended loading.

Check the alignment of the belt with the tensioner and the rest of the front-end accessory drive.

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Finishing Steps

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 WARNING 

Batteries can emit explosive gases. To reduce the possibility of personal injury, always ventilate the compartment before servicing the batteries. To reduce the possibility of arcing, remove the negative (-) battery cable first and attach the negative (-) battery cable last.
  • Disconnect the battery. Refer to Procedure 013-009 in Section 13.
  • Operate the engine and check for belt squeal. Excessive belt squeal indicates excessive belt slip.
  • If belt squeal is present, check the routing of the belt to make sure the belt is installed correctly on each pulley.

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Last Modified:  22-Sep-2010