GM Service Manual Online
For 1990-2009 cars only

Tools Required

    • J 3289-20 Holding Fixture
    • J 22912-B Split Plate Bearing Puller
    • J 23907 Slide Hammer with Bearing Adapter
    • J 26941 Bushing and Bearing Remover - 3-4 inch
    • J 45380 Transfer Case Rear Bushing Remover and Installer
    • J 45759 Assembly Fixture

    Object Number: 824069  Size: SH

    Important: The service information is for the following transfer cases. When a specific service procedure affects servicing a different component it will be mentioned.

       • The NVG 236 used in the T Pickup and Utility, which has a preload clutch
       • The NVG 246 used in the K Pickup carryover model, which has a non-preload clutch
       • The NVG 246 used in the K Utility vehicles, which has a non-preload clutch
       • The NVG 246 used in the K Pickup new model style, which has a preload clutch

  1. Attach the J 45759 to the transfer case using the adapter studs. All of the transfer case disassembly procedures can be performed with the case mounted to the J 45759 .

  2. Object Number: 819573  Size: SH
  3. Mount the J 3289-20  (1) to a sturdy workbench.
  4. Install the J 45759  (2) into J 3289-20  (1) and secure with pivot pin.

  5. Object Number: 857299  Size: SH
  6. Remove the fill plug (1) and the drain plug (2) and drain the transfer case fluid.

  7. Object Number: 662850  Size: SH
  8. Remove the encoder motor mounting bolts.
  9. Remove the encoder motor assembly.
  10. Remove the actuator insulator gasket.

  11. Object Number: 163610  Size: SH
  12. Remove the plastic vent from the case; a NEW aluminum vent must be installed during assembly.

  13. Object Number: 163714  Size: SH
  14. Remove the rear vehicle speed sensors (VSS).

  15. Object Number: 662047  Size: SH
  16. Remove the front VSS.

  17. Object Number: 163722  Size: SH
  18. Remove the access hole plug.

  19. Object Number: 678215  Size: SH

    Notice: Do not damage the sealing surfaces of the transfer cases or the shafts when prying the seals for removal. Damaging the sealing surface may cause leakage or require replacement of the damaged component.

  20. Remove the input shaft seal by prying it out of the front case.

  21. Object Number: 715670  Size: SH
  22. Remove the rear output shaft seal.

  23. Object Number: 801274  Size: SH
  24. Inspect the rear output shaft bushing for scoring or wear.
  25. Remove the rear output shaft bushing using the J 45380 .
  26. • Install the finger section of the J 45380 in front of the bushing.
    • Install the tube and forcing screw assembly to the finger section. Ensure the forcing screw is backed out.
    • Using a wrench on the forcing screw, remove the rear output shaft bushing.

    Object Number: 163733  Size: SH
  27. Remove the transfer case retaining bolts and washers.
  28. Mark the location of any brackets.


    Object Number: 695581  Size: SH

    Notice:  Do not nick, scratch or damage the sealing surface. The sealing surface is a machined surface. Damage to the machined surface can cause leakage.

  29. Insert a flat-blade screwdriver into the slot on the left side of the transfer case.

  30. Object Number: 695583  Size: SH
  31. Insert a flat-blade screwdriver into the slot on the right side of the transfer case.
  32. With equal pressure, press down on the screwdrivers in order to separate the front case half and the rear case half.

  33. Object Number: 649760  Size: SH
  34. Insert a pair of snap ring pliers and release the outer retaining ring for the rear output shaft bearing.

  35. Object Number: 163737  Size: SH
  36. Remove the rear case half from the front case half.

  37. Object Number: 724251  Size: SH
  38. Remove the oil pump wear sleeve, a new wear sleeve is required.

  39. Object Number: 701586  Size: SH
  40. Remove the rear output shaft rear bearing retaining ring.

  41. Object Number: 701589  Size: SH
  42. Remove the rear output shaft rear bearing.

  43. Object Number: 701592  Size: SH
  44. Remove the rear output shaft speed sensor reluctor wheel.

  45. Object Number: 163856  Size: SH
  46. Remove the magnet.

  47. Object Number: 163872  Size: SH
  48. Disconnect the oil pump suction pipe from the oil pump screen.
  49. Remove the oil pump screen from the front case half.
  50. Remove the oil pump suction pipe from the oil pump inlet hole.
  51. Remove the oil pump suction pipe O-ring from the oil pump.

  52. Object Number: 892466  Size: SH

    Important: The rear output shaft may be an original design (2) or the replacement design (1). The original design rear output shaft (2) uses an oil pump wave washer above the oil pump and a retaining ring under the oil pump. The original design rear output shaft (2) is identified by the splines in the area by the oil gallery hole. The replacement design rear output shaft has a smooth area by the oil gallery hole. Ensure to follow the steps for the correct rear output shaft.

  53. Inspect the rear output shaft to identify as an original design (2) or the replacement design (1).

  54. Object Number: 886580  Size: SH
  55. If original design rear output shaft, remove the oil pump wave washer.
  56. Remove the oil pump assembly.

  57. Object Number: 163898  Size: SH
  58. If original design rear output shaft, remove the rear output shaft retaining ring.

  59. Object Number: 701617  Size: SH
  60. Remove the drive sprocket retaining ring.

  61. Object Number: 857307  Size: SH
  62. Remove the driven sprocket retaining ring.

  63. Object Number: 163905  Size: SH

    Important: If the chain and sprockets are to be used again, mark the relationship of the chain to the sprockets in order to mark the wear patterns.

  64. Remove the chain and sprockets.
  65. Remove the chain from the drive sprocket and driven sprocket.

  66. Object Number: 701622  Size: SH
  67. Remove the rear output shaft assembly.
  68. Mount the rear output shaft assembly in a soft-jaw vise with the output end up.

  69. Object Number: 164262  Size: SH
  70. Remove the clutch assembly retaining ring. Push down on the clutch pressure plate to access the retaining ring.

  71. Object Number: 1273611  Size: MH

    Important: There are different clutch components between the NVG 236 preload clutch, the NVG 246 non-preload clutch used with the K Pickup carry over model and the Utility, and the NVG 246 preload clutch used with the K Pickup new model style. For correct disassembly, the following clutch components are different:

       • The clutch pressure plate
          - The non-preload clutch pressure plate (1) does not have a groove for the clutch spring.
          - The preload clutch pressure plate (2) has a groove for the clutch spring.
       • The clutch friction plate
          - The non-preload friction plate (3) has 8 grooves on the outside and 8 grooves on the inside.
          - The preload friction plate (4) has 20 grooves.
       • The clutch spring
          - The preload clutch spring (5) is located in the groove of the pressure plate.
          - The non-preload clutch spring (6) is located in the clutch hub.
       • The clutch oil restrictor plate (7) is used only with the preload clutch.
       • The clutch backing plate
          - The NVG 236 clutch backing plate (8) is thicker and has a step shoulder.
          - The NVG 246 clutch backing plate (9) is thin and only a notch.

  72. Remove the clutch pressure plate assembly.

  73. Object Number: 801276  Size: SH
  74. If preload clutch, remove the clutch pressure plate spring.

  75. Object Number: 801280  Size: SH
  76. Remove the clutch pressure plate bearing with the clutch pressure plate hub from the clutch pressure plate.

  77. Object Number: 801281  Size: SH
  78. Inspect the bearing for being faulty. Refer to Transfer Case Cleaning and Inspection .
  79. If the bearing is faulty, using a hydraulic press and a suitable adapter, remove the clutch pressure plate bearing from the clutch pressure plate hub.
  80. Discard the bearing after removal.

  81. Object Number: 163895  Size: SH
  82. Remove the clutch hub retaining ring.
  83. Remove the clutch housing and hub assembly from the rear output shaft.

  84. Object Number: 801282  Size: SH
  85. If preload clutch, remove the clutch hub oil restrictor plate.

  86. Object Number: 893402  Size: SH
  87. If non-preload clutch, remove the clutch spring.

  88. Object Number: 801283  Size: SH
  89. Turn the clutch assembly over on a work bench.
  90. Remove the clutch housing.
  91. Remove the clutch hub.
  92. Remove the clutch backing plate.

  93. Object Number: 670237  Size: SH

    Important: Do not wash the clutch friction or inner pressure plates in cleaning solvent.

  94. Separate the clutch plates for inspection.
  95. Remove and discard the shim or shims.

  96. Object Number: 164507  Size: SH
  97. Remove the oil restrictor from the rear output shaft, if replacing the shaft.

  98. Object Number: 165429  Size: SH
  99. Inspect the bearing in the clutch housing for being faulty. Refer to Transfer Case Cleaning and Inspection .
  100. If the bearing is faulty, use a brass drift and a hammer to remove the bearing.

  101. Object Number: 701623  Size: SH
  102. Remove both of the clutch lever pivot pins with the aluminum washers and the O-ring seals.

  103. Object Number: 164548  Size: SH
  104. Remove the shift detent spring bolt.
  105. Remove the following components:
  106. • The shift detent plunger plug O-ring seal
    • The shift detent spring
    • The shift detent plunger

    Object Number: 701627  Size: SH
  107. Remove the clutch lever from the control actuator lever.

  108. Object Number: 165035  Size: SH
  109. Remove the shift fork shaft.

  110. Object Number: 712346  Size: SH
  111. Remove the range shift fork and the range shift sleeve as an assembly.
  112. It may be necessary to lightly pry the roller on the shift fork from the control actuator lever.


    Object Number: 801284  Size: SH
  113. Remove the range shift sleeve from the range shift fork.

  114. Object Number: 164463  Size: SH
  115. Remove the outer retaining ring for the input gear bearing.

  116. Object Number: 712161  Size: SH

    Important: Depending on the version of the NVG 246 transfer case, it may have either a 4 pinion gear or 6 pinion gear planetary carrier assembly. The 4 pinion gear planetary carrier is used with transmission RPO M30 and the input gear splines are 27 teeth. The 6 pinion gear planetary carrier is used with transmission RPO MT1 and MN8 and the input gear splines are 32 teeth. The NVG 236 uses a 3 pinion carrier. The repair procedures are the same for all planetary carriers.

  117. Remove the high/low planetary carrier.

  118. Object Number: 705373  Size: SH
  119. For the NVG 236, remove the front output shaft dust seal.

  120. Object Number: 670241  Size: SH

    Notice: Do not damage the sealing surfaces of the transfer cases or the shafts when prying the seals for removal. Damaging the sealing surface may cause leakage or require replacement of the damaged component.

    Important: The front output shaft seal for the NVG 246 may be the internal sealing design. The seal is a two piece and force fit on the front output shaft. The removal of the NVG 246 seal is different and shown later in the disassembly procedures.

  121. For the NVG 236, remove the front output shaft seal.

  122. Object Number: 804188  Size: SH
  123. For the NVG 236, remove the front output shaft bearing retaining ring.

  124. Object Number: 804189  Size: SH
  125. For the NVG 236, remove the front output shaft assembly.

  126. Object Number: 895080  Size: SH
  127. For the NVG 246, remove the inner retaining ring for the front output shaft bearing.

  128. Object Number: 895089  Size: SH
  129. For the NVG 246, using a soft-face hammer, remove the front output shaft, with the bearing, from the front case half.

  130. Object Number: 895092  Size: SH
  131. For the NVG 246, using a suitable punch, remove the front output shaft seal from the front case half.

  132. Object Number: 895094  Size: SH
  133. For the NVG 246, remove the outer retaining ring for the front output shaft bearing.

  134. Object Number: 895096  Size: SH
  135. For the NVG 246, inspect the front output shaft bearing for being faulty. Refer to Transfer Case Cleaning and Inspection .
  136. For the NVG 246, remove the bearing from the front output shaft. Do not use the bearing again after removal.

  137. Object Number: 801286  Size: SH
  138. If damaged, remove the speed sensor reluctor wheel from the front output shaft using a hydraulic press. Removal of the reluctor wheel for the NVG 246 is shown. The removal of the reluctor wheel for the NVG 236 is the same.

  139. Object Number: 165060  Size: SH
  140. For the NVG 246, if the cup plug in the front output shaft is leaking, remove the plug using a brass drift.

  141. Object Number: 165318  Size: SH
  142. Remove the planetary gear shaft retaining ring.

  143. Object Number: 165308  Size: SH
  144. Remove the planetary carrier lock plate.

  145. Object Number: 165300  Size: SH
  146. Remove the input gear front thrust washer.

  147. Object Number: 165294  Size: SH
  148. Remove the input gear from the planetary carrier.

  149. Object Number: 165286  Size: SH
  150. Remove the input gear rear thrust washer.

  151. Object Number: 165322  Size: SH
  152. Inspect the pilot bearing in the input gear for being faulty. Refer to Transfer Case Cleaning and Inspection .
  153. Remove the pilot bearing from the input gear using a brass drift and a hammer.

  154. Object Number: 712116  Size: SH
  155. Remove the input bearing retaining ring.

  156. Object Number: 712123  Size: SH
  157. Remove the input bearing.

  158. Object Number: 801287  Size: SH
  159. For the NVG 236, remove the front output shaft front bearing retainer ring.
  160. For the NVG 236, remove the front output shaft front bearing.

  161. Object Number: 801288  Size: SH
  162. Inspect the front output shaft rear bearing for being faulty. Refer to Transfer Case Cleaning and Inspection .
  163. If the bearing is faulty, remove the bearing using the J 23907  (2) and the J 26941  (1).

  164. Object Number: 801289  Size: SH
  165. Remove the retaining ring for the control actuator lever shaft.

  166. Object Number: 801290  Size: SH
  167. Remove the control actuator lever shaft.
  168. Inspect the control actuator lever bearing and seal for being faulty. Refer to Transfer Case Cleaning and Inspection .
  169. If the bearing is leaking or faulty, remove the bearing from the case.