LUBRICATION
| CAUTION | Transmission oil circulates between the transmission and the transfer case. In situations where transmission failures circulate debris into the transfer case, the transfer case must be disassembled, cleaned, and inspected for damage. See appropriate OVERHAUL article. |
SERVICE INTERVALS
Every 12 months or at engine oil change intervals, check front axle and transfer case and add lubricant when necessary. A fluid loss could indicate a problem. Check and have it repaired, if needed. Check vent hose at transfer case for kinks and proper installation. More frequent lubrication may be required if vehicle frequently used off road.
CHECKING FLUID LEVELS
To get an accurate reading, the vehicle should be on a level surface. If the level is below the bottom of the filler plug hole, you may need to add some lubricant. (Scheme 16) When the differential is cold, add enough lubricant to raise the level to 1/2" (12 mm) below the filler plug hole. See RECOMMENDED FLUIDS. When the differential is at operating temperature (warm), add enough lubricant to raise the level to the bottom of the filler plug hole.
Scheme 16
RECOMMENDED FLUIDS
| Application | Fluid Type |
|---|---|
| NVG 126 (NP4) & NVG 226 (NP8) | AUTO-TRAK II GM Fluid (P/N 12378508) |
TRANSFER CASE FLUID TYPE
Draining
- Raise and support vehicle.
- Remove the fuel tank shield, if equipped. See «FUEL TANK SHIELD»(ref-155255-S08708319192003061100000) under REMOVAL & INSTALLATION in REMOVAL & INSTALLATION - BRAVADA, ENVOY, ENVOY XL & TRAILBLAZER article.
- Remove the transfer case shield as follows, if equipped: Remove the transfer case shield mounting bolts (3) from the transmission support. (Scheme 17) Remove the transfer case shield (2) from transmission support.
- Remove filler plug located on rear of transfer case. (Scheme 18)
- Remove drain plug from bottom of transfer case.
- Allow the transfer case to drain completely.
Scheme 17
Scheme 18
Refilling
- Apply Pipe Sealant (GM P/N 12346004) or equivalent to the drain plug threads.
- Reinstall drain plug. (Scheme 18) Tighten drain plug to specification. See «TORQUE SPECIFICATIONS»(ref-155057-S21515925542003060500000).
- Fill transfer case through oil filler plug hole to specified capacity using recommended fluid. See «RECOMMENDED FLUIDS»(ref-155057-S00915510292003060500000) and «FLUID CAPACITIES»(ref-155057-S15713822552003060500000).
- Apply Pipe Sealant (GM P/N 12346004) or equivalent to the fill plug threads.
- Reinstall filler plug. Tighten filler plug to specification. See «TORQUE SPECIFICATIONS»(ref-155057-S21515925542003060500000).
- Install the transfer case shield as follows, if equipped: Install the transfer case shield (2) to the transmission support. Ensure that the J-nuts (1) are in place. (Scheme 17) Install the transfer case shield mounting bolts (3). Tighten the transfer case shield mounting bolts to specification. See «TORQUE SPECIFICATIONS»(ref-155057-S21515925542003060500000).
- Install the fuel tank shield, if equipped. See «FUEL TANK SHIELD»(ref-155255-S08708319192003061100000) under REMOVAL & INSTALLATION in REMOVAL & INSTALLATION - BRAVADA, ENVOY, ENVOY XL & TRAILBLAZER article.
- Lower the vehicle.