GM Astro/Safari 1985-1996 Repair Guide

Drive Axle (Front and Rear)

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Several axle ratios are available with the various powertrain applications.

FLUID RECOMMENDATIONS



Standard Axle

GM recommends you use SAE 80W-90 GL5 gear or or an equivalent lubricant that meets the standards of their part No. 1052271. In cold climates, GM recommends the use of SAE 80W gear oil for some applications. Refer to your owners manual for more details.

You should drain and refill the rear differential at first oil change, then it should be checked at every other oil change. Periodic fluid replacement should not be necessary under normal service, but the fluid should be changed if the vehicle is operated in water which is as deep as the axles. Change the fluid at every other engine oil change if the van is used in severe service, such as trailer towing or severely dusty conditions.

Changing the front drive axle fluid on these vehicles usually requires its removal and partial disassembly. The fluid in the front drive axle should not need to be changed unless the axle is removed for repair. It should however, be checked at each engine oil change.

Locking Axle

Always use GM Rear Axle Fluid No. 1052271 or equivalent SAE 80W-90 GL5 lubricant. Check with your owners manual or parts supplier, on a few earlier models covered by this guide it may be necessary to add 4 ounces of GM Fluid No. 1052358 (limit-slip additive) before refilling. BUT GM SPECIFICALLY WARNS AGAINST using limited slip additive on 1996 locking differentials and does not mention its use for many of the late-model vehicles covered by this guide.

You should drain and refill the rear differential at first oil change, then it should be checked at every other oil change. Periodic fluid replacement should not be necessary under normal service, but the fluid should be changed if the vehicle is operated in water which is as deep as the axles. Change the fluid at every other engine oil change if the van is used in severe service, such as trailer towing or severely dusty conditions.

Changing the front drive axle fluid on these vehicles usually requires its removal and partial disassembly. The fluid in the front drive axle should not need to be changed unless the axle is removed for repair. It should however, be checked at each engine oil change.

LEVEL CHECK



See Figures 1 and 2



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Fig. Fig. 1: Use a ratchet and extension to remove the filler plug and check the axle fluid



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Fig. Fig. 2: Gear oil can be added using a pump or a squeeze bottle

When checking the fluid, the vehicle must be level. If it was necessary to raise and support the vehicle to access the filler plug, the vehicle must be supported at sufficient points (all wheels or 4 points on the frame) so it is sitting level and is not tilted forward/backward or to one side.

The lubricant level should be checked at each chassis lubrication and maintained at the bottom of the filler plug hole.

  1. If necessary for access, raise and support the vehicle on jackstands; BUT be sure the vehicle is level.
  2.  
  3. Remove the filler plug, located at the passenger side of the differential carrier. Most plugs are designed to accept the driver from a 3 / 8 in. ratchet, breaker bar or extension.
  4.  
  5. Check the fluid level, it should be level with the bottom of the filler plug hole, add fluid (if necessary).
  6.  


CAUTION
Watch for sharp threads in the filler plug opening. When present, they can give you a nasty cut.

  1. When you are finished, install the filler plug and tighten to 26 ft. lbs. (35 Nm).
  2.  

DRAIN & REFILL



Rear Axle Assembly

See Figures 3, 4, 5, 6, 7, 8 and 9



Click image to see an enlarged view

Fig. Fig. 3: Because there is usually no drain plug, the rear axle cover must be removed to change the fluid



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Fig. Fig. 4: Begin by cleaning loose dirt from around the cover to prevent contamination when it is removed



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Fig. Fig. 5: Loosen and remove the cover bolts, then ...



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Fig. Fig. 6: ... carefully break the gasket seal at the housing (DO NOT damage the cover/housing)



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Fig. Fig. 7: With the gasket seal broken, pull the cover back at the bottom allowing the fluid to drain



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Fig. Fig. 8: Once most of the fluid has been emptied into the drain pan, remove the cover from the housing



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Fig. Fig. 9: If equipped, the magnet should be cleaned of metal particles

Refer to Fluid Recommendations in this section for information on when to change the fluid.

  1. Drive the vehicle until the lubricant reaches operating temperature. Warm fluid flows better, removing more impurities with the oil.
  2.  
  3. Raise and support the rear of the vehicle on jackstands; BUT be sure the vehicle is level (for refilling purposes and to help assure proper draining of the axle housing).
  4.  
  5. Use a wire brush to clean the area around the differential. This will help prevent dirt from contaminating the differential housing while the cover is removed.
  6.  
  7. Position a drain pan under the rear axle.
  8.  
  9. Unscrew the retaining bolts and remove the rear cover. When removing the cover, a small prytool may be used at the base of the cover to gently pry it back from the axle housing, breaking the gasket seal and allowing the lubricant to drain out into the container. You may wish to leave 1 of the cover bolts, loosely installed, to keep the cover from falling suddenly (creating quite a mess) once the seal is broken. Be careful not to use excessive force and damage the cover or housing.
  10.  

To install:
  1. Carefully clean the gasket mating surfaces of the cover and axle housing of any remaining gasket or sealer. A putty knife is a good tool to use for this.
  2.  
  3. Install the rear cover using a new gasket and sealant. Tighten the retaining bolts using a crosswise pattern to 20 ft. lbs. (27 Nm).
  4.  

Make sure the vehicle is level before attempting to add fluid to the rear axle or an incorrect fluid level will result.

  1. Refill the rear axle housing using the proper grade and quantity of lubricant as detailed earlier in this section. Install the filler plug, operate the vehicle and check for any leaks.
  2.  

 
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