Cummins ISX11.9 CM2250 – Service Manual 008-087   Cooling Fan Belt Tensioner

Check the tensioner arm, pulley, and stops for cracks. If any cracks are detected, the tensioner must be replaced.

With the belt installed, verify that neither tensioner arm stop is in contact with the spring casing stop. If either stop is touching, the drive belt must be replaced.

After replacing the belt, if the tensioner arm stops are still in contact with the spring case stop, replace the tensioner.

Check the location of the drive belt on the belt tensioner pulley. The belt should be centered on, or close to the middle of, the pulley. Unaligned belts, either too far forward or backward, can cause belt wear, belt roll-off failures, or increase uneven tensioner bushing wear.

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 batteries. Refer to the OEM service manual.
• Remove the cooling fan drive belt. Refer to Procedure 008-002 in Section 8.

With the belt removed, verify that the tensioner arm stop is in contact with the spring case stop. If these two components are not touching, the tensioner must be replaced.

Remove the capscrew and belt tensioner from the bracket.

Check the belt for damage.

Transverse (across the belt width) cracks are acceptable.

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

If the belt is frayed or has any piece of material missing, the belt is unacceptable and needs to be replaced.

WARNING  The belt tensioner is spring loaded. Do not attempt to disassemble the tensioner. Personal injury can result.

WARNING  When using solvents, acids, or alkaline materials for cleaning, follow the manufacturer’s recommendations for use. Wear goggles and protective clothing to reduce the possibility of personal injury.

Check the tensioner for dirt buildup. If the tensioner has dirt buildup, remove and use solvent to clean the belt tensioner.

Measure the clearance between the tensioner spring case and the tensioner arm to verify tensioner wear-out and uneven bearing wear. If the clearance exceeds 3 mm [0.12 in] at any point, the tensioner failed and must be replaced as a complete assembly.

Experience has revealed that tensioners generally will show a larger clearance gap near the lower portion of the spring case, resulting in the upper portion rubbing against the tensioner arm. Always replace the belt when a tensioner is replaced.

1. Tensioner cap
2. Tensioner arm
3. Spring case
4. Tensioner pulley
5. Clearance gap.

Check the belt tensioner pulley and body for cracks. If cracks are found, replace the tensioner.

Inspect the tensioner for evidence of the tensioner arm contacting the tensioner cap. If there is evidence of contact, the pivot tube bushing has failed and the tensioner must be replaced.

Spin the tensioner pulley. The pulley must spin freely. If the pulley does not spin freely, replace the belt tensioner.

Align the dowel pins on the tensioner with the alignment holes in the mounting bracket.

Install the tensioner and mounting capscrew.

Tighten the capscrew.

After checking the torque, use a breaker bar with a 1/2-inch ratchet to rotate the tensioner slowly away from the area of belt contact (clockwise and down).

If the arm rotates with any roughness or hesitancy, replace the tensioner.

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.

• Connect the batteries. Refer to the OEM service manual.
• Install the cooling fan drive belt. Refer to Procedure 008-002 in Section 8.
• Operate the engine and check for proper operation.