Drivetrain - Rear Differential Whine Coasting/Decel.
2007 Service BulletinsTSB SB07-07-S001
ISSUE DATE: JANUARY 2007
Whine Noise From Rear Axle
Affected Vehicles
2005-2007 Isuzu Ascender (UT) With 4.2L Engine
Service Information
Condition:
Some customers may comment on a slight axle whine heard only on deceleration or coast conditions. The noise peaks at about 77 to 83 km/h (48 to 52 mph) before quieting at about 72 km/h (45 mph).
Possible Cause:
Inherent ring and pinion gear whine.
All gear driven units, such as automotive rear axles, produce some level of noise that cannot be eliminated with conventional adjustments and repairs. "Inherent" axle noise can be described as a slight noise heard only at a certain speed (typically between 72-96 km/h (45-60 mph). The presence of this noise is not indicative of a functional concern with the axle assembly. However, some customers may find that this "inherent" axle noise is unacceptable.
Correction:
Diagnose and replace rear propeller shaft with new tuned torsional damper rear propeller shaft.
Service Procedure
Important:
The new service propeller shafts are only designed to correct the noise condition described above. They will not be effective if repair attempts are made to correct other noise conditions. If propeller shaft replacement is needed for any other reason, the existing service part number propeller shaft should be used.
If the noise is not correctly diagnosed as "inherent" and having a peak in the narrow speed range of 77 to 83 km/h (48 to 52 mph) on deceleration or coast conditions, the addition of a tuned torsional damper propeller shaft can aggravate the perceptible noise level. It is extremely important to first diagnose the rear axle noise as "inherent" before installing a new tuned torsional damper propeller shaft. Refer to the applicable diagnostic information in the Rear Drive Axle subsection of the Service Manual.
Replace the rear propeller shaft with a new tuned torsional damper propeller shaft using the applicable part number listed below. The new propeller shaft incorporates a damper assembly to lessen noise transmitted from the rear axle assembly. The new propeller shaft should be used ONLY after diagnosis concludes that it is an "inherent" rear axle noise and no physical damage or incorrect adjustment exists. Refer to the Propeller Shaft subsection of the Service Manual for rear propeller shaft replacement procedures.
Parts Information
Warranty Claim Information Use the labor operation shown.
NOTE:
1. Labor Time includes administrative time allowance.
2. Information released on paper and electronic format prior to bulletin release cannot be updated. For the most current and up to date information refer to the website
3. Always refer to the Isuzu Service Policy Procedure Manual for specific details on warranty coverage and policies.
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