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How To Replace Rear Differential Cover 02-09 Chevy Trailblazer

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  1. step : Raising and Securing the Vehicle (0:29)
    • Raise the vehicle with the jack
    • Secure the vehicle on jack stands
    • Prepare a drain pan
  2. step : Removing the Differential Cover (0:34)
    • Remove all the 13mm bolts except three
    • Use a screwdriver to pry out the differential cover
    • Allow the differential fluid to drain
    • Remove the remaining bolts
    • Remove the gasket carefully so that you can reuse it
  3. step : Cleaning the Differential (2:11)
    • Wipe dirt and residue off the differential with a rag or paper towels
    • Wipe dirt and residue off the differential cover
    • Use gasoline or mineral spirits if necessary
    • Clean any metal filings from the magnet in the cover
  4. step : Replacing the Differential Cover (3:39)
    • Inspect the gasket for wear
    • Attach the less worn side of the gasket at the bottom
    • Scrape off any scale on the cover
    • Apply gasket sealant to the cover
    • Put the gasket and cover in place
    • Hold the cover in place with two bolts
    • Install the remaining bolts
    • Tighten the bolts preliminarily
    • Tighten the bolts to 20 foot-pounds with a torque wrench
    • Tighten the bolts in a crossing pattern
    • Check all the bolts in rotational order
  5. step : Filling the Differential Fluid (5:20)
    • Loosen the 3/8 inch plug with a hammer
    • Remove the 3/8 inch plug
    • Fill with 1.75 Liters of 80W90 Lubricant
    • Watch for fluid to run out of plug hole
    • Reinsert the plug
    • Tighten the plug
    • Wipe any lubricant off
    • Wipe off the bottom of the differential cover
    • After driving, check the differential cover for leaks
    • If there are leaks, retighten the bolts

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In this video we're going to show you how to remove and replace the differential cover, which is also the same as changing the differential fluid for the back, or the rear, of this 2004 Chevy Trailblazer. You'll probably want a jack and jack stands. Although you don't have to jack the vehicle up, it does make it a lot easier. You will also need a 13-millimeter socket and ratchet.

Raise and support the vehicle. Then have a catch pan underneath. Then you have ten 13 millimeter bolts that you have to remove. They're easy enough. I just have them just using a small wrench just to show you. They shouldn't be tightened that much. They should be tightened about 12 to 15 foot-pounds each, so they should come apart fairly easily. I'm not going to bore you with watching me take out every one, so we'll skip forward a little bit. Now we've got all the bolts out; I'm working on the last 3. As I start loosening up this last bottom one, you'll start seeing some fluid dripping out of the screw-in. That's exactly why you want to have a catch pan underneath. Now I have removed my catch pan up closer. Take a screwdriver; just pry a little bit on the cover. Get the fluid coming out faster, and then just wait for it to stop draining.

Fast forward here. I just removed those last 2 bolts after the dripping of the fluid has slowed down quite a bit. Now we want to carefully remove that gasket. Again, be careful with it because you do want to reuse it.
Use some rags, paper towels, whatever and just clean as much dirt and gunk off as you can: the more the better. The more you get out, the less it's floating around in there. If you want, put it in neutral, spin it around, and keep wiping it off. Now, with your pan do the same thing. It's very interesting to see quite a bit of gunk. You can actually use some gasoline or mineral spirits. I'm going to go over to my parts washer and clean that all off.

I've got my differential cleaned off. Here's my cover. I cleaned it off. This here's a magnet. You want to make sure you clean that off really well. What that does is, as these gears grind together, they shave just teeny microscopic pieces off. The magnet just catches them and holds them. The gasket that came off, you want to reuse it. The only change I'm going to make is . you can see there's a little more rust and stuff. That was the bottom. I'm actually going to make that the top now, just so it seals. It's more important to give it a good seal on the bottom than the top. The other thing I did with my cover: I scraped off any scale and then I put a very, very, very thin coat of gasket sealant on it, just where it was scaly, just to make sure that it gets a good seal.

What I'm going to do is put one bolt through, grab my gasket, put my bolt through there, put my gasket over here, another bolt right there, screw it up into place, start those two. I'm just going to speed up as I install the rest of the bolts, and then we'll skip the part where I tighten them preliminarily with a wrench. We'll go right to torquing them. You want to torque them to 12 foot-pounds each, then you kind of want to cross; I do the top, then I go down to the bottom, then I go over to the side, and then the opposite side until I think I've done them all. Then I actually start at the bottom and go in order right around, just to make sure that they have all been torqued properly.

If you feel around, you're going to find a plug with a 3/8 inch hole in here. What you might want to do is give it a good tap with a hammer. Just helps to break it loose. Then make sure your extension of your ratchet goes well in there. Then pull it and break it loose. Now you're going to want to use an 80W90 lubricant. It's going to take 1.75 liters, which is basically almost 2 of these bottles. Just a little accessory that I have for these occasions is a little tube, so I can just put this bottle up here. As I'm filling the last of my fluid, I'm going to put that right up there. What I'm going to watch for is the fluid come running down there. That's when I know it's got enough. I'm starting to see it drip down, so now I can put my plug back in. If I look at that, it took a full one of these and almost 3/4 of one, so the amount's about right. Put the plug in and use my ratchet. You don't have to make it incredibly tight, because you want to be able to get it apart again at a later date. Just wipe everything down. Wipe down the bottom of your differential cover really well. That way, after you drive it for a little while, you can just check down here, see if you see any dripping. If you see some dripping, then you can tighten up your bolts on your cover just a little bit more. That'll usually stop it if it does drip.

We hope this helps you out. Brought to you by, your source for quality replacement parts and the best service on the Internet. Please feel free to call us toll-free, 888-844-3393. We're the company that's here for you on the Internet and in person.

Tools needed for replacement:

    General Tools

  • Funnel
  • Drain Pan
  • Jack Stands
  • Hammer
  • Floor Jack

  • Materials, Fluids, and Supplies

  • Paper Towels
  • Cloth Rags
  • Gear Oil
  • Gasket Adhesive
  • Mineral Spirits

  • Ratchets & Related

  • 3/8 Inch Drive Ratchet
  • Torque Wrench
  • Socket Extensions
  • Ratchet

  • Sockets - Metric

  • 13mm Socket

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