How to Change a Rear Axle Pinion Seal on a Chevy S-10

Written by kevin mclain
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Chevrolet S-10 model trucks come equipped with a pinion seal that is seated inside the rear axle housing. The purpose of the pinion seal is to prevent differential fluid from leaking out of the rear end while the driveshaft is turning the rear yoke. If the pinion seal is ever damaged or it is defective, it will leak differential fluid. Replace the pinion seal as soon as possible to prevent all the fluid from leaking out of the rear end and burning up the gears and the axle.

Skill level:
Moderately Challenging

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Things you need

  • Safety glasses
  • Wheel chocks
  • Oil catch pan
  • Chalk
  • 1/2-inch drive ratchet
  • 1/2-inch drive socket set
  • Bungee cord
  • 1/2-inch drive air impact wrench
  • 32-mm socket
  • Flange puller
  • Adjustable wrench
  • Hand held sledge hammer
  • Small chisel
  • Pliers
  • Clean rags
  • Blue RTV silicone
  • New pinion seal
  • Pinion seal driver
  • Hand pump with plastic tube
  • 80/90 gear oil

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  1. 1

    Park the Chevy S-10 on a flat surface and turn the engine off. Engage the parking brake. Position the wheel chocks in front of both front wheels and behind both front wheels.

  2. 2

    Climb under the rear of the S-10 and locate the rear of the driveshaft where it connects to the rear-end yoke. Slide the oil catch pan underneath the rear end yoke. Mark the top of the yoke and the top of the driveshaft with a piece of chalk to indicate the positioning of the yoke and the driveshaft.

  3. 3

    Loosen and remove the 11-mm bolts from the u-joint straps with a ratchet and a 11-mm socket. Pull the bolts and the strap off and place them in a safe area. Pull back on the driveshaft to remove it from the yoke. Use a hand held sledge hammer if necessary to tap the end of the driveshaft back until it is free of the yoke. Hang the driveshaft up to the bottom frame of the truck with a bungee cord.

  4. 4

    Loosen and remove the pinion nut with an air impact wrench and a 32-mm socket. Hold the yoke with one hand to prevent it from moving. Use the impact wrench with the other hand to remove the pinion nut. Turn the nut counterclockwise to loosen and remove. Once the nut is loose, finish unscrewing the nut with your fingers. Pull the nut and the flat washer behind the nut off the pinion shaft, and place them in a safe area.

  5. 5

    Remove the rear yoke from the pinion shaft with the flange puller. Position the puller around the flange and the front of the pinion shaft. Turn the adjustable bolt on the end of the puller clockwise with an adjustable wrench until the yoke is completely off the pinion shaft. Remove the puller.

  6. 6

    Position the flat end of a small chisel under a part of the pinion seal. Tap the chisel with the hammer until the seal is raised up off the seal seat. Move the chisel to another location under the seal and tap the chisel until the seal is raised out of the seal seat. Continue this process until the seal is completely out of the seat. Pull the seal out of the seat with the pliers. When the seal is out, the differential fluid will pour out into the oil catch pan.

  7. 7

    Clean the pinion seal seat thoroughly with clean rags. Remove all of oil and debris from the seal seat. Apply a thin bead of blue RTV silicone around the edges of the new pinion seal. Position the new seal face-to-face with the seal seat. Place the seal driver over the front of the new seal. Tap the end of the driver with the hammer until the new seal is completely flush with the end of the seal seat. Remove the seal driver. Inspect the seal to ensure that it is completely flush with the outer facing of the pinion seal seat.

  8. 8

    Reinstall the yoke, flat washer and the pinion nut. Make sure that the mark on the top of the yoke is facing up. Screw the nut on tightly and use the air impact wrench to tighten the pinion nut until it stops turning. Once the nut stops turning, remove the impact wrench and reinstall the driveshaft with the u-joint strap and strap bolts. Make sure the mark on top of the driveshaft is lined up with the mark on the top of the yoke. Tighten the strap bolts down tight with the ratchet and 11-mm socket.

  9. 9

    Remove the rear differential fill plug on the back of the rear end with the square end of a 3/8-inch drive ratchet. Turn the ratchet counterclockwise to loosen and remove the plug. Pull the plug out and place it on the ground. Insert the plastic tube of the hand-held pump into the rear end and pump the gear oil into the rear end until it begins to pour out of the fill hole.

  10. 10

    Remove the plastic tube and screw the fill plug back into the fill hole. Tighten the fill plug down tight with the ratchet. Move the oil catch pan and all tools out from under the truck. Remove the wheel chocks from both front wheels.

  11. 11

    Test drive the truck for about 10 minutes. Park the truck and recheck the fluid level inside the rear end fill hole. Add more gear oil to the rear end if necessary.

Tips and warnings

  • Most auto parts stores carry seal drivers and flange pullers.
  • Do not hit the facing of the seal with a hammer -- doing so can result in warping the seal or damaging the seal and will cause the seal to leak.
  • Always wear safety glasses when hammering on steel or metal.

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