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John, Master A.S.E Automotive technician
Category: Chevy
Satisfied Customers: 9176
Experience:  A.S.E MasterTechnician A1-A8 w/L1,38 years experience General Motors Master Technician
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96 Silverado 1500: I replace the rear main seal..5.3L

Resolved Question:

How do I replace the rear main seal on my '96 Silverado 1500 with the 5.3L engine? I'm really trying to save myself from paying the $800 they're quoting me.
Submitted: 7 years ago.
Category: Chevy
Expert:  John replied 7 years ago.


The rear main oil seal in your vehicle is a 1 piece seal & the transmission must be removed to install it.Here is the information you asked for.

4.3L, 5.0L, 5.7L and 1991-98 7.4L Engines

See Figures 10, 11, 12

Special tool J-35621 (or J-38841), or its equivalent seal installer, will be necessary for this job.

  1. Remove the transmission.

Click image to see an enlarged view

Fig. Fig. 10: Rear main seal and retainer-4.3L, 5.0L and 5.7L engines

Click image to see an enlarged view

Fig. Fig. 11: Oil seal removal notches

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Fig. Fig. 12: Oil seal installation tool

  1. With manual transmission, remove the clutch.
  2. Remove the flywheel or flexplate.
  3. Remove the oil pan.
  4. Unfasten the oil seal retainer screws and nuts.
  5. Remove the oil seal retainer and gasket.
  6. Insert a small prying tool in the notches provided in the seal retainer and pry out the old seal. Be VERY CAREFUL to avoid nicking or scratching the sealing surfaces of the crankshaft.

To install:

  1. Install a new gasket on the block and install the oil seal retainer. Tighten the screws and nuts to 11 ft. Lbs. (15 Nm).
  2. Install the oil pan.
  3. Coat the inner and outer diameters of the new seal with clean engine oil.
  4. Using seal tool J-35621, or equivalent, position the seal on the tool.
  5. Thread the seal tool attaching screws into the holes in the crankshaft end and tighten them securely with a screwdriver.
  6. Turn the installer handle until it bottoms.
  7. Remove the tool.
  8. Install the flywheel/flexplate, clutch (if applicable), and the transmission.

6.5L diesel engines

See Figure 13

  1. Remove the transmission and flywheel.
  2. Remove the oil seal using a suitable tool and discard the seal.
  3. Clean the oil seal bore in the block and inspect the seal-to-engine contact surfaces.

To install:

  1. Coat the crankshaft surface with clean engine oil and lightly coat the sealing area of the new oil seal.
  2. Install the new seal with the spring cavity towards the engine, onto the crankshaft.
  3. Using tool J-39084 or equivalent, drive the seal in until tool bottoms out against the block and the crankshaft rear main bearing cap.
  4. Remove the tool.
  5. Install the flywheel and transmission.

Click image to see an enlarged view

Fig. Fig. 13: Using tool J-39084 or equivalent, drive the seal in until tool bottoms out against the block and the crankshaft rear main bearing cap-6.5L engines

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See Figures 1 and 2

It would be best to drain the transmission before starting.

  1. Disconnect the battery ground cable.
  2. Remove the air cleaner.
  3. If equipped, disconnect the detent or TV cable at the throttle lever.
  4. On 4WD models, remove the transfer case shift lever knob and boot.
  5. Raise and support the truck on jackstands.
  6. Disconnect the shift linkage from the transmission.
  7. If it is necessary to disconnect the fuel line, relieve the fuel system pressure. Disconnect the fuel lines.
  8. Remove any skid plates that would interfere with transmission removal.
  9. Drain the transmission fluid.
  10. Remove the driveshaft(s), after matchmarking its/their flanges.
  11. Detach the speedometer cable or Vehicle Speed sensor (VSS) connector, downshift cable, vacuum modulator line, shift linkage, throttle linkage, electrical wiring, the fluid cooler lines, or any other component that would interfere with transmission removal.
  12. Remove the dipstick tube.
  13. If necessary, remove the starter motor.
  14. If necessary, disconnect the support bracket at the catalytic converter.
  15. Support the transmission on a transmission jack and unbolt the transmission rear mount or the transfer case adapter from the crossmember.
  16. Remove the crossmember.
  17. Remove any transmission support braces. Note their exact positions for installation.
  18. Remove the torque converter underpan, matchmark the flywheel and converter, and remove the converter bolts.
  19. If necessary for clearance, move the exhaust system aside.
  20. If necessary for clearance, disconnect the parking brake cable.
  21. Remove the transfer case and the adapter.
  22. Support the engine on a jack and lower the transmission slightly for access to the upper transmission-to-engine bolts.
  23. Remove the transmission-to-engine bolts and pull the transmission back. Rig up a strap or keep the front of the transmission up so the converter doesn't fall out.

To install:

Installation is the reverse of removal but please note the following important steps.

  1. Tighten the transmission-to-engine bolts to 35 ft. lbs. (47 Nm).


Make sure that the torque converter-to-flexplate matchmarks are aligned, the torque converter is flush with the flywheel and the converter turns freely by hand.

  1. On all except 1996-98 models, tighten the converter bolts to 50 ft. lbs. (68 Nm).
  2. On 1996-98 models, tighten the converter bolts to 46 ft. lbs. (63 Nm).
  3. Tighten the transmission support brace bolts to 35 ft. lbs. (47 Nm).
  4. On all except 1991-98 models, tighten the crossmember retainers to 35 ft. lbs. (47 Nm).
  5. On 1991-98 models tighten the crossmember retainers to 56 ft. lbs. (77 Nm).
  6. On 1988-94 4WD models, tighten the transfer case-to-transmission attaching bolts to 24 ft. lbs. (32 Nm) and the transfer case-to-frame bracket bolts to 35 ft. lbs. (47 Nm).
  7. On 1995-98 4WD models, tighten the adapter-to-transfer case and adapter-to-transmission bolts to 33 ft. lbs. (45 Nm).

Click image to see an enlarged view

Fig. Fig. 1: Automatic transmission and related components-THM400, 4L60E and 4L80E

Click image to see an enlarged view

Fig. Fig. 2: Automatic transmission and related components-THM700R4

Customer: replied 7 years ago.
So I don't need to do anything with the motor, i.e., drain the oil, etc.?
Thanks for all your help. I really appreciate it. Still nervous about taking out the transmission though.
Expert:  John replied 7 years ago.
You do not need to drain oil,but I would drain oil & change filter with the completed job.Have a good place to do this & a good transmission jack (transmission is pretty heavy).Get someone to help you,possibly large person & strong.
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