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How to Replace Alternator 98-00 Chevy Blazer S10

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How to Replace Alternator 98-00 Chevy Blazer S10

Created on: 2021-01-16

In this video, 1A Auto shows you how to replace a broken or bad alternator in a 98-00 Chevy Blazer S10.

  1. step 1 :Disconnect the battery
    • Use your 8 mm wrench to disconnect the negative battery terminal
  2. step 2 :Remove the serpentine belt
    • Locate your serpentine belt routing diagram.
    • Use your 3/8 drive ratchet to release tension from the belt tensioner pulley
    • Remove the serpentine belt.
  3. step 3 :Remove the alternator
    • Unbolt the three 15 mm bolts
    • Pry up the alternator and remove the 13 mm lead bolt.
    • Unplug the alternator from the wiring harness.
  4. step 4 :Install the new alternator
    • Use a rubber mallet to work the alternator and 15 mm mounting bolts back into place.
    • Secure the 15 mm bolts with your socket and ratchet.
    • Plug in the wiring harness and connect the lead with your 13 mm socket and ratchet.
  5. step 5 :Install the serpentine belt
    • Check the serpentine belt for flaws, cracks or frays on the smooth side.
    • Use your routing diagram to route the belt.
    • Release the tension from the belt tensioner pulley to get the belt over the last pulley.
  6. step 6 :Reconnect the battery
    • Reconnect the negative battery terminal with your 8 mm wrench.

Tools needed for replacement

  • General Tools

    Rubber Mallet

  • Ratchets & Related


    3/8 Inch Drive Ratchet

  • Sockets - Metric

    13mm Socket

    15mm Socket

  • Wrenches - Metric

    8mm Wrench

Installation Video
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Brought to you by, your source for quality replacement parts and the best service on the Internet.

Hi, I'm Mike Green. I'm one of the owners of 1A Auto. I want to help you save time and money repairing and maintaining your vehicle. I'm going to use my 20 plus years experience restoring and repairing cars and trucks like this to show you the correct way to install parts from The right parts installed correctly. That's going to save you time and money. Thank you, and enjoy the video. In this video, we're going to show you alternator replacement on this 2000 Chevy S-10 Blazer, with a 4.3 Liter. This is the same for any '98 to 2000 S-10 Blazer, S-15 Jimmy, and then the S-10 and S-15 pick-ups with the 4.3 Liter as well as the Sonoma with the 4.3 Liter. Tools you'll need are 8mm wrench, 3/8-inch ratchet, and 13mm and 15mm sockets.

Use an 8mm wrench to disconnect the negative side of your battery. You'll want to find your belt-routing diagram, which is usually right here, right above your radiator.
Now you want to take a 3/8-drive ratchet handle and 3/8 is the measurement of the square drive gear, basically, and you insert that. Your belt tensioner is right down there where I'm going with the wrench. You can see it right there. You insert the drive into a square hole in the tensioner, and then you turn the tensioner counterclockwise, and you can see as I do that, the belt loosens up, and then you can slide it right off the idler pulley right there. Then release your tensioner. Now, just kind of grab your belt, pull it off the pulleys, the alternator, and power steering pump and everything, and then down around off of the crank, and there's kind of a shot of your belt out.

Your alternator is held in by three bolts. One here, one over here, and then one right back here. I'm going to fast forward through moving those three 15mm bolts. Okay. Now I'll just take a screwdriver, pry both sides. Okay. Now, as you bring it up, you'll want to unplug this plug here. Actually, let's do this one first, so you pull this back, and this is a 13mm. You want to make sure you have your battery unplugged before you do this, or you'll get a good shock. Once that's unplugged, see there's a little tab right here. Just kind of pry with your thumb, pull that off, and your alternator is out. To reinstall the alternator, and there's nothing wrong with this one, I'm just showing you how to do it. Let's plug in our lead in the side here first, which is pretty easy. It only goes in one way. Then put our battery lead back on. Tighten that up nice and firm. And then you're going to put the alternator in position here. Now position your alternator so that your mount should go on right down into where the bracket is.

Okay, so here I was able to push down that side and get that bolt started, and for the other side, what I actually do have to do is break out a rubber mallet. You want to make sure you use a rubber mallet, and I'm using some force, but you can pretty much just gently tap it down in, and as you're tapping, now I'm putting the bolt into place. And as I tap it down in, I'm pushing on the bolt a little bit, and I start getting the bolt to go in, tap it into place a little more, and get the bolt to go in the rest of the way. Okay, and now I'll just put the wrench on there, and start tightening up those bolts and put the last third one on the back side, and tighten them all up. Okay. You want to tighten those bolts up to35 to 40 foot-pounds. Then make sure on the back of the alternator that boot that covers the terminal in the back is in place. You don't want that metal, that short terminal touching anything. It could set off sparks.

And now, here I'm just going to fast forward through putting the belt back on. If you want to see this in regular speed, just check out our other videos for the serpentine belt for the S-10 Blazer or you can probably pick up just about enough. If you got it off, chances are you can get it back on. Just follow the routing diagram. Okay, and now we can take our negative battery cable and reconnect it.

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

  • Rubber Mallet

  • Ratchets & Related

  • Ratchet
  • 3/8 Inch Drive Ratchet

  • Sockets - Metric

  • 13mm Socket
  • 15mm Socket

  • Wrenches - Metric

  • 8mm Wrench

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