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How to Replace Serpentine Belt Tensioner 02-05 Chevy Trailblazer

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How to Replace Serpentine Belt Tensioner 02-05 Chevy Trailblazer

Created on: 2021-01-16

Check out this video to learn how to replace the serpentine belt tensioner on your 02-05 Chevy Trailblazer with the 4.2L engine.

  1. step 1 :Removing the Serpentine Belt
    • Familiarize yourself with the serpentine belt route
    • Use the 3/8 inch drive ratchet to turn the tensioner clockwise
    • Loosen the setpentine belt
    • Remove the belt
  2. step 2 :Removing the Belt Tensioner
    • Remove the 15mm bolt from the tensioner
    • Remove the tensioner
  3. step 3 :Replacing the Tensioner
    • If necessary, remove the 13mm bolt from the pulley bearing and replace the pulley
    • Slide the tensioner bolt into place
    • Push the tensioner toward the engine
    • Push the locating bolt into place
    • Tighten the bolt by hand
    • Tighten the bolt to between 35 – 40 foot-pounds
  4. step 4 :Reinstalling the Serpentine Belt
    • Inspect the belt for wear
    • Replace the belt with a new one if necessary
    • Start the belt at the crank pulley
    • Bring it over the water pump
    • Bring it around the A/C pulley
    • Bring it around the idler pulley
    • Bring it around the tensioner pulley
    • Bring it around the power steering pulley
    • With the 3/8 inch drive ratchet and a breaker bar or pipe for leverage pull the tensioner over
    • Putt the belt around the alternator
    • Release the tensioner
    • Check that the belt is routed correctly

Tools needed for replacement

  • Ratchets & Related

    A Piece of Pipe (for leverage)


    3/8 Inch Drive Ratchet

    1/2 Inch Breaker Bar

  • Sockets - Metric

    15mm Socket

Installation Video
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Hi, I'm Mike Green. I'm one of the owners of 1A Auto. I want to help you save time and money repairing or 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 how to remove and replace the serpentine belt tensioner on this 2004 Chevy Trailblazer with the 4.2 liter inline 6. Tools you'll need are a 3/8 inch drive ratchet with a long handle or a pipe for some extra leverage, and a 15mm socket and ratchet.

First thing you want to note is how the Serpentine belt is on your vehicle. You see it goes across up there to the alternator and down to an idler pulley, then down around the A/C pulley way down there, then up and around the water pump and fan. Then it wraps back down and around the crank and back up to the tensioner right there. We're going to place the camera over here. What you want is a ratchet with a 3/8 inch drive end on it. There's a square hole in our tensioner here. Here's a shot of it from the other angle of my ratchet in my tensioner. You're going to take your ratchet and you're going want to push it clockwise. As I push down on the tensioner that loosens the belt.

I can remove it up here from the alternator and slowly let my wrench back, being careful not to pinch my hand in anything. Now my belt can come off. Now you want a 15mm socket and a ratchet down on the bolt. You probably can't see hardly anything I'm doing except for my arm. We're just going to fast forward through removing that bolt. Now with your tensioner, if it's your pulley, the bearing in your pulley, you can actually replace it by removing that 13mm bolt and putting it back in. My tensioner is actually, even though it's a little dirty, it's in fine shape, so I'm just going to reinstall it. You can see it's got a locating tab right here.

Essentially what I'm doing here, because you can't really tell, because all's you're looking at is my elbow, is I'm reaching down in there and I feel for the hole where the bolt goes into. Then I just basically push that bolt into that hole and start turning it until it grabs. Once I know the bolt's in, then, I push the tensioner towards the engine and get that locating tab into the right spot. It's kind of in and the bolt's started, and I know I've got the locating tab in. I'll just fast forward through this. First, tighten up that bolt by hand, then tighten it up with the wrench. It probably should be tightened to about 35 to 40 foot-pounds. Check the condition of your belt. Ours is in pretty good shape. See there's a little bit of cracking on the ribs, but that's not too big of a deal.

You want to check the whole length. Where they sometimes can get bad is where they're joined together, and if it's getting bad there you'll know it because you'll see it. I don't see it, so this one's okay. If you do need a new belt, we carry them at I can't really film putting this on too well, but I'll try and put it together in detail as best I can. I'm putting a loop down and around the crank pulley, which is the largest pulley at the bottom of the engine. Loop it down there, then I'll bring it back up and over my water pump right here on top, and then way down and around my A/C pulley, which is a smaller pulley at the bottom of the engine, then up and around my idler pulley here, on this side around my tensioner pulley, and then around my power steering pulley.

Now, basically, I have the whole thing routed except for having it on the alternator. Here's my belt. I take a piece of pipe actually, you can see the top of the camera there, put it on to my ratchet that's in my tensioner, and that just gives me a lot more leverage. Pull my tensioner over, put the belt onto my alternator there, let the tension back, take out the pipe, take out the wrench, and make sure everything is routed correctly, and it appears to be, and we're all set.

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:

    Ratchets & Related

  • A Piece of Pipe (for leverage)
  • Ratchet
  • 3/8 Inch Drive Ratchet
  • 1/2 Inch Breaker Bar

  • Sockets - Metric

  • 15mm Socket

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