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Butch
Butch, Master ASE Certified Technician
Category: Chevy
Satisfied Customers: 375
Experience:  Master ASE Certified Technician, 10 years experience, 60+ GM certificates, 150+ GM training courses
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My 02 Siverado Z71 is leaking oil. Ive replaced the oil

Customer Question

My '02 Siverado Z71 is leaking oil. I've replaced the oil pan gasket with no improvement. Will I need to drop the tranny/transfer, driveshafts, etc. in order to change the rear main seal? Or perhaps pull the engine? Engine: 5.3L.
Submitted: 8 years ago.
Category: Chevy
Expert:  Butch replied 8 years ago.

HiCustomer

 

You will have to pull the transmission to change the rear main seal. So that means you will have to take out the drive shaft, then transfer case and then the transmission. It sounds like a lot but it is not that hard on these. I will give you a little tip that will save you time and money, there is a park/neutral switch that is on the transmission. The connector that plugs in to this is glued in, so you will not be able to unplug it. You will need to remove the two 10mm bolts that hold it on the transmission and slide it off the shaft. I have seen many people try to unplug these and end up breaking them. Here is a pic of it.

When you remove the transfer case, take off the 15mm nuts that hold it to the adapter and leave the adapter on the transmission. If you need any more help, just ask.

 

Thanks,

Butch

 

Park/Neutral Position Switch Replacement
Object Number: 394471  Size: SH

Butch and 8 other Chevy Specialists are ready to help you
Customer: replied 8 years ago.
The auto parts house tells me the rear main is a one-piece seal. I now know that the oil pan gasket is flat (no front and rear "horseshoes"), and I can't tell if I will need special tools to replace the seal. Can you give me any insight into how to proceed once the flywheel is off? You mention an adaptor at the transfer case. Can you be more specific? Also, the pic you sent is unclear. If you can just tell me what side of the tranny the neutral/park switch is on(driver/passenger), and how many wires are in the plug, I think I can work with that.
Expert:  Butch replied 8 years ago.

Once you get the flywheel off, you can use a seal puller or large screw driver to pry the old seal out. There is a tool that is used to press the rear main in, but you can do it without it if you are careful. The new seal should come with a plastic ring already in it that will help get it started over the crankshaft. After that you can use a light hammer and a half inch drive extension (or anything else that is flat on the end like a large socket) and just tap around the seal lightly and evenly until the gasket is in the same place as the old one was. The adapter is between the transmission and transfer case. It has 15mm bolts that hold it to the transmission and 15mm nuts that hold it to the transfer case. It is much easier to get the transfer case out if you unbolt it from the adapter and leave the adapter on the transmission than if you unbolt the adapter from the transmission and take it out with the transfer case. The park neutral switch is on the drives side and has a shaft that it slides on to. The shaft is what the shift cable rotates when you put it in gear. It has 2 plugs, one has 4 wires and the other has 6. Let me know if I can be of more help.

Thanks,

Butch

Customer: replied 8 years ago.

When I changed the oil pan gasket, it looked like there was a plate on the front (timing cover) and rear of the engine. While I am changing the main seal, should I go ahead and change the gasket at this rear plate? Could said gasket be the cause of my leak? My truck has 175K miles on it, but I take good care of it.

 

Thanks Butch. I am going to be tackling this project tomorrow. I might need you to come and help. My back's getting sore just thinking about it. Would it be any easier to pull the engine instead of dropping the tranny?

 

Thanks again.

Ross

Expert:  Butch replied 8 years ago.

If it appears to be leaking I would go ahaed and chang it. This does however require the use of special alighnment tool. I will post the procedure and a pic of the tool. As far as pulling the engine instead of the transmission I would stick with the transmission. If you are doing this on a flat surface you can just remove the transfer case, unbolt the transmission and torque converter bolts, and use a floor jack with a piece of wood on it, and slide the transmission back far enough to get the flywheel off. The hardest part if you don't have a lift, is going to be getting the transfer case out, and getting the torque conveter bolts out.

 

Crankshaft Rear Oil Seal Housing Replacement

Special Tools

J 41476 Front and Rear Cover Alignment Tool
J 41479-2A Crankshaft Rear Oil Seal Installation Guide

Removal Procedure


    Object Number: 680413  Size: SH

  1. Remove the engine flywheel. Refer to Engine Flywheel Replacement.
  2. Remove the oil pan-to-rear oil seal housing bolts (1).
    Object Number:(NNN) NNN-NNNN Size: SH

  3. Remove the rear oil seal housing bolts (1).
  4. Remove the rear oil seal housing (2) and gasket (3). Discard the gasket.
  5. Remove and discard the rear oil seal (4).

Installation Procedure

    Important:

    Do not reuse the crankshaft oil seal or rear cover gasket.
    Do not apply any type of sealant to the rear cover gasket, unless specified.
    The special tool in this procedure is used to properly center the crankshaft rear oil seal.
    All gasket surfaces should be free of oil or other foreign material during assembly.
    The crankshaft rear oil seal MUST be centered in relation to the crankshaft.
    An improperly aligned rear cover may cause premature rear oil seal wear and/or engine assembly oil leaks.

     


    Object Number:(NNN) NNN-NNNN Size: SH

  1. Apply a 5 mm (0.2 in) bead of sealant, 20 mm (0.8 in) to the 2 joints (a) at the rear of the block/pan. Refer to Adhesives, Fluids, Lubricants, and Sealers.
    Object Number: 63228  Size: MH

  2. Inspect the rear oil gallery plug for proper installation.

Installation Procedure - Cover with Seal

  1. Install the J 41479-2A cone and bolts onto the rear of the crankshaft.
    Object Number:(NNN) NNN-NNNN Size: SH

  2. Install the NEW rear housing gasket (1), rear housing with seal (2), rear housing-to-engine bolts (3) and oil pan-to-rear housing bolts (4).

    Notice: Refer to Fastener Notice in the Preface section.

  3. Tighten the rear housing-to-engine bolts (3) until snug. Do not overtighten.

    Tighten
    Tighten the oil pan-to-rear housing bolts (4) to 12 N·m (106 lb in).

  4. Tighten the rear housing-to-engine bolts (3).

    Tighten
    Tighten the bolts to 30 N·m (22 lb ft).

  5. Remove the J 41479-2A .
  6. Install the engine flywheel. Refer to Engine Flywheel Replacement.

Installation Procedure - Cover without Seal


    Object Number:(NNN) NNN-NNNN Size: SH

  1. Position a NEW rear oil seal housing gasket (3) and the housing (2) to the engine.
  2. Install the rear oil seal housing bolts (1) until snug. Do not overtighten.
  3. Rotate the crankshaft until 2 opposing flywheel bolts holes are parallel to the oil pan surface.
    Object Number: 451716  Size: SH

    Important: The tapered legs of the alignment tool must enter the rear cover oil seal bore.

  4. Install the J 41476 and bolts onto the rear of the crankshaft.
  5. Tighten the J 41476 bolts until snug. Do not overtighten.
    Object Number: 680413  Size: SH

  6. Install the oil pan-to-rear oil seal housing bolts (1).

    Tighten

    1. Tighten the oil pan-to-rear cover bolts to 12 N·m (106 lb in).
    2. Tighten the rear oil seal housing-to-engine bolts to 30 N·m (22 lb ft).
  7. Remove the J 41476 .
  8. Install a NEW crankshaft rear oil seal. Refer to Crankshaft Rear Oil Seal Replacement.
  9. Install the engine flywheel. Refer to Engine Flywheel Replacement.