GM S10/S15/Sonoma Pick-Ups 1982-1993 Repair Manual

Pinion Oil Seal



See Figures 1, 2 and 3

The following procedure requires the use of the Pinion Holding tool No. J-8614-10 or equivalent, the Pinion Flange Removal tool No. J-8614-1, J-8614-2, J-8614-3 or equivalent, and the Pinion Oil Seal Installation tool No. J-23911 or equivalent.

  1. Matchmark the driveshaft and pinion flange to assure they are reassembled in the same position.
  3. Disconnect the driveshaft from rear axle pinion flange and support the shaft up in body tunnel by wiring the driveshaft to the exhaust pipe. If the U-joint bearings are not retained by a retainer strap, use a piece of tape to hold bearings on their journals.
  5. Mark the position of the pinion stem, flange and nut for reference. On vehicles through 1991 this will reference mark will be used to set pre-load during assembly.
  7. For 1992-93 vehicles, use an inch lbs. torque wrench to measure the amount of torque necessary to turn the pinion, then note this measurement as it is the combined pinion bearing, seal, carrier bearing, axle bearing and seal preload.
  9. Using a pinion holding tool such as No. J-8614-10, and the appropriate pinion flange removal tool No. J-8614-1, J-8614-2, J-8614-3 (as applicable) or equivalents, remove the pinion flange nut and washer.
  11. With suitable container in place to hold any fluid that may drain from rear axle, remove the pinion flange.
  13. Remove the oil seal by driving it out of the differential with a blunt chisel; DO NOT damage the carrier.
  15. Examine the seal surface of pinion flange for tool marks, nicks or damage, such as a groove worn by the seal. If damaged, replace flange as outlined later in this section.
  17. Examine the carrier bore and remove any burrs that might cause leaks around the O.D. of the seal.
  19. Apply GM seal lubricant No. 1050169 or equivalent to the outside diameter of the pinion flange and sealing lip of new seal. Drive the new seal into place using a correctly sized installation tool.

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Fig. Fig. 1: Removing the pinion nut using a pinion holding fixture tool

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Fig. Fig. 2: A puller and adapter should be used to withdraw the pinion from the housing

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Fig. Fig. 3: Use the appropriately sized installation tool to drive the new seal into position.

  1. Install the pinion flange and tighten nut to the same position as marked in Step 3. Tighten the nut a little at a time and turn the pinion flange several times after each tightening in order to set the rollers.
  3. For 1992-93 vehicles, measure the torque necessary to turn the pinion and compare this to the reading taken during removal. Tighten the nut additionally, as necessary to achieve the same preload as measured earlier.
  5. For vehicles through 1991 hold the pinion flange and tighten the nut 1 / 16 in. (1.6mm) beyond the original alignment marks.

If fluid was lost from the differential housing during this procedure, be sure to check and add additional fluid, as necessary. For details, please refer toChapter 1of this manual.

  1. Remove the support then align and secure the driveshaft assembly to the pinion flange. The original matchmarks MUST be aligned to assure proper shaft balance and prevent vibration.