Transfer Case - Loud Metallic Pop Noise

Classification:
TF92-001



Section:
Transfer Case



Reference:
TECHNICAL BULLETIN NTB92-075



Models:
1990-91 4WD Truck



Date:
September 15, 1992



TRANSFER CASE "POP"' NOISE


APPLIED MODEL:
1990-91 Truck/Pathfinder with VG30 and 4WD

APPLIED DATE:
Vehicles built prior to October 28, 1991


SERVICE INFORMATION

On some 1990-91 Truck/Pathfinder vehicles equipped with the VG30 engine and four-wheel drive, customers may complain of a loud metallic "pop" noise which occurs when accelerating from a stop. The noise may be described as occurring in both forward or reverse gears, and may be most noticeable when changing direction (forward to reverse or reverse to forward).





The source of the noise may be the mainshaft and low/high synchronizer hub in the transfer case. The "pop" noise may occur when high torque loads cause the splines of the low/high synchronizer hub to move slightly on the splines of the mainshaft during acceleration. On the applied models, there is an interference fit between the low/high synchronizer hub and the mainshaft splines. A countermeasure mainshaft has been designed which has splines that will not have an interference fit with the splines of the low/high synchronizer hub. Refer to illustration.



SERVICE PROCEDURE

1. Remove the transfer case assembly and install the countermeasure mainshaft. Since the new mainshaft splines do not have an interference fit with the low/high synchronizer hub, the low/high hub will slide onto the countermeasure mainshaft splines by hand (will not require a press operation as before). The original low/high synchronizer hub can be reinstalled.

2. Reassemble and install transfer case assembly.

3. Fill transfer case with proper lubrication fluid (Dexron II).

4. Drive vehicle and confirm that the "pop" noise has been eliminated.





PARTS INFORMATION






WARRANTY INFORMATION