GM Full Size Vans 1987-1997 Repair Guide

Rear Axle

Print

FLUID RECOMMENDATIONS



Rear axles use SAE 80W-90 GL-5 gear oil. Positraction® axles must use special lubricant available from dealers. If the special fluid is not used, noise, uneven operation, and damage will result. There is also a Positraction® additive used to cure noise and slippage. Positraction® axles have an identifying tag, as well as a warning sticker near the jack or on the rear wheelwell.

LEVEL CHECK



See Figures 1 through 6

Lubricant levels in the rear axle should be checked as specified in the Maintenance Interval Charts, later in this section. To check the lubricant level:

  1. Park on level ground.
  2.  
  3. Remove the filler plug from the differential housing cover.
  4.  
  5. If lubricant trickles out, there is enough. If not, carefully insert a finger and check that the level is up to the bottom of the hole. Front axles should be full up to the level of the hole when warm, and 1 / 2 in. (12.7mm) below when cool.
  6.  



Click image to see an enlarged view

Fig. Fig. 1: The rear axle differential filler plug may be in either of these locations

  1. Lubricant may be added with a funnel or a squeeze bulb. Rear axles use SAE 80W-90 GL-5 gear lubricant.
  2.  

Positraction® limited slip axles must use a special lubricant available from dealers. If the special fluid is not used, noise, uneven operation, and damage will result. There is also a Positraction® additive to cure noise and slippage. Positraction® axles have an identifying tag, as well as a warning sticker near the jack or on the rear wheelwell.



Click image to see an enlarged view

Fig. Fig. 2: Use a ratchet and extension to remove the filler plug and check the axle fluid



Click image to see an enlarged view

Fig. Fig. 3: Gear oil can be added using a pump or a squeeze bottle until it begins to trickle out, then reinstall the filler plug:

DRAIN & REFILL



No intervals are specified for changing axle lubricant, but it is a good idea, especially if you have driven in water above the axle vents.



Click image to see an enlarged view

Fig. Fig. 4: Using a wire brush, clean the bolts and edges of the differential cover:

No intervals are specified for changing axle lubricant, but it is a good idea every year or so. If you have driven in water above the axle vents, change the fluid immediately.

  1. Park the vehicle on the level with the axles at normal operating temperature.
  2.  
  3. Place a pan of at least 6 pints capacity under the differential housing.
  4.  
  5. Remove the filler plug.
  6.  
  7. If you have a drain plug, remove it. If not, unbolt and remove the differential cover.
  8.  
  9. Install the drain plug or differential cover. Use a new gasket if the differential cover has been removed.
  10.  
  11. Install the drain plug and tighten it so it will not leak. Do not overtighten.
  12.  

It is usually a good idea to replace the gasket at this time.

  1. Refill the differential with the proper lubricant - do not overfill!
  2.  
  3. Install and tighten the filler plug to the following specifications:

    8 5 / 8 in. - 26 ft. lbs. (35 Nm)
     
    9 1 / 2 in. - 26 ft. lbs. (35 Nm)
     
    9 3 / 4 in. - 26 ft. lbs. (35 Nm)
     
    10 1 / 2 in. - 26 ft. lbs. (35 Nm)
     

  4.  
  5. Road test the van and check for any leaks.
  6.  



Click image to see an enlarged view

Fig. Fig. 5: After removing the bolts, carefully pry the bottom of the cover off and drain the fluid:



Click image to see an enlarged view

Fig. Fig. 6: After the oil has drained, remove the differential cover:

 
label.common.footer.alt.autozoneLogo