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How to Replace Serpentine Belt Tensioner 01-05 BMW 325Xi

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  1. step : Removing the Radiator Fan and Shroud (0:23)
    • Disconnect the negative battery cable by loosening the 10mm nut
    • Remove the air collector push pin retainers
    • Remove the air collector
    • Disconnect the two electrical connectors on the passenger side of the fan shroud
    • Remove the T25 screw from the passenger side corner of the fan shroud
    • Remove the push pin retainer from the driver side corner of the fan shroud
    • Loosen the radiator fan clutch using a fan clutch tool
    • The fan clutch is reverse threaded
    • Remove the fan and fan shroud
  2. step : Removing the Serpentine Belt (4:24)
    • Turn the AC belt tensioner clockwise with a 16 mm socket
    • Remove the AC belt
    • Release the AC belt tensioner
    • Loosen the serpentine belt tensioner with a 16 mm socket
    • Insert a pin through the tensioner hold holes
    • Remove the serpentine belt
  3. step : Removing the Serpentine Belt Tensioner (6:11)
    • Remove the 16 mm idler pulley bolt to remove the idler pulley
    • Turn the serpentine belt tensioner clockwise with a 16 mm socket to remove the pin from the hold holes
    • Release the tensioner
    • Remove the two 13 mm tensioner bolts
    • Remove the tensioner
  4. step : Installing the Serpentine Belt Tensioner (8:26)
    • Hold the serpentine belt tensioner in position
    • Install the two 13 mm tensioner bolts
    • Torque the top 13 mm bolt to 18 ft-lb
    • Turn the tensioner clockwise with a 16 mm socket to remove the pin
    • Torque the lower 13 mm bolt to 18 ft-lb
    • Install the idler pulley using the alignment tab as a guide
    • Install the 16 mm idler pulley bolt
    • Torque the 16 mm idler pulley bolt to 30 ft-lb
    • Replace the idler pulley cover if equipped
  5. step : Installing the Serpentine Belt (10:37)
    • Slide the serpentine belt over the crank pulley, to the right around the power steering pulley, loop the belt around the tensioner pulley, and back over to the water pump pulley, bring the belt over the alternator pulley, then under the idler pulley
    • Loosen the tensioner with a 16 mm socket to get the belt under the idler pulley, then remove the pin and then release the tensioner
    • Loosen the AC tensioner with a 16 mm socket
    • Install the AC belt around the crank pulley and the AC pulley, and over the tensioner pulley
    • Release the AC tensioner
  6. step : Installing the Radiator Fan and Shroud (12:41)
    • Lower the radiator fan and fan shroud together
    • Tighten the fan clutch onto the water pump pulley by turning it clockwise
    • Torque the fan clutch nut to 22-29 ft-lb if able
    • Install the fan shroud push pin retainer on the driver side
    • Install the fan shroud T25 screw on the passenger side
    • Reconnect the two electrical connectors on the passenger side of the fan shroud
    • Insert the air collector into the air filter box
    • Secure the air collector with the push pin retainers
    • Reconnect the negative battery cable and tighten the 10 mm nut

What's up, guys? I'm Andy from 1A Auto. In this video, I'm going to show you how to replace the serpentine belt tensioner on this 2001 BMW 325xi. If you need this part or other parts for your vehicle, click the link in the description and head over to one

With the trunk open, over on the right side or the passenger side, there should be a cover that goes right here. This vehicle doesn't have one, but you're going to want to remove that cover. Battery is located right here. First thing I'm going to do is take a 10 millimeter socket and a ratchet, loosen up this nut for the negative terminal. And that's loose. Slide off the cable. Slide it out of the way. I'm going to take these pushpins out right here. I'm just going to use some side cutters. Get the center pin, pull that up, and then slide it out. Be careful not to cut that.

Get those out. Let's grab this piece, slide it out. We're gonna disconnect this connector right here. Just push down on that. Slide that out. Then another connector right here. I'm going to slide the wiring out first, just like that. Then the connector will come out. I'll just slide that to the side like that. I'm going to take a T25 and a ratchet. Take this screw out right here.

Just going to use this trim tool from Take this push clip out, pull that out. All right. Now that is loose. But what we need to do is, we need to take the fan off because the fan has to come out with the shroud as one. What we need to do to take the fan off is, we need to disconnect the fan clutch from the engine side. This is attached to one of the pulleys right there. So sometimes these are somewhat difficult to get off, so what we're going to do is use this tool.

We actually sell this at with many different sizes. This happens to be the 32 millimeter. That's going to slide on there. And then we slide this on. And with a pneumatic air hammer, we're going to give it a couple of bumps, and it's going to loosen up that nut, and we should be able to get it off. All right. So now I'm going take the tool. Now this fan clutch happens to be on there reverse thread, so it's going to seem like you're tightening it, but you're actually loosening it. So we'll go like that, put our air hammer on there. Make sure you wear hearing protection and eye protection.

All right, so that's loose. Took a little bit of effort, but I got it. Now you can slide the tool off. We'll just move it a little bit. Here we go. And you should be able to just spin it off like that. Might need the tool once in awhile, or you could use a wrench that fits, a 32 millimeter wrench.

All right. Now I'm just going to keep loosening this up. Be careful. You don't want the fan to fall. You don't want it to smash into the radiator, especially if you're going to reuse the radiator. If you're replacing it, that's not a big deal. So as I get closer to the end, I'll just move the fan and just grab the blade. There we go. We can slide this right up just like that. For this job that we're doing, you don't necessarily have to have the coolant drained, or the coolant hoses off, or the air box out, but it's easier to see with the camera, so we're going to leave that stuff off. Just to keep in mind, you don't have to do all that to get to this position.

I'm going to take a 16 millimeter socket and a ratchet, and I want it on tightening. I'm going to go down here and get on the tensioner right there. You could use a serpentine belt tool as well. And then I can loosen up the belt just like that. That's how it looks from underneath. With that loosened up, I can grab the belt, slide it off the crank, and then slide it off the AC compressor. I'm going to take this serpentine belt off. What I'm going to need is a hex key. This happens to be a five millimeter hex key.

And I'm going to use this 16 millimeter socket and a ratchet. Put the ratchet on tighten, and the right here on the tensioner is a little area you can put the socket. And then you're going to tighten it like you're tightening a bolt. That's going to loosen up the tension on the belt. We can take this hex key, and slide it in that position. That's going to lock the tensioner. Let that go. Then we can grab the belt, slide it off the idler, slide it off the alternator right there. We can pull our socket away, pull it off the water pump, off the tensioner, off the crank, and off the power steering pump. Just like that.

I'm going to take a 16 millimeter socket and a ratchet, and we'll take this bolt out right here. Loosen it up. Loosen that up, slide that bolt out. Before I take this tensioner out, I do want to get my hex key back. And if I took the tensioner off, I wouldn't be able to get that hex key out too easily. And the bottom bolt is going to be hard to get to. So what I'm gonna do is take my 16 millimeter socket and a ratchet, move it. You can use the belt tool as well. And then slide my tool out, and then gently release the pressure on that. And now I can access the bolt underneath and up top.

I'm going to use a 13 millimeter socket and a ratchet, loosen this bolt up here. And then underneath here, loosen the bolt up underneath as well. I'm going to need an extension for the lower one. Put an extension on for the lower one. Loosen that up. Now I can loosen these up by hand. Now take the top one out. I'm just going to support the tensioner as I take it up, and then slide it up.

Here's the old part. Here's the new part from one It's machined the same as the old one, has the same mounting positions. Has the same position for the tensioner tool, has the same position for the lock pin. And it comes with the lock pin. Leave that in there until you install it. Get yours at, and you'll be ready to rock and roll

With the new tensioner, I'm going to take the bolts. I'm going to get this bolt started before I position it down here. Get the bottom one in. I'm going to try to snug that one up as much as I can by finger tight, and then take the top one. Get the top one lined up. Now I'm going to take a 13 millimeter socket and a torque wrench. I can torque this top bolt to 18 foot pounds. Get that one tight. Now I can't access the bottom one yet. What I'm going to do is take a 16 millimeter socket and a ratchet, and we're just going to move the ratchet. I'm going to pull that pin out.

Oops. Going the wrong way. Nope, I was going the right way. Grab the pin carefully, pull it out, and then carefully loosen up on the ratchet. Watch your fingers, you don't want to get caught right there. Now I can access the bolt. Then I'll torque that bottom bolt to the same 18 foot pounds. The new idler pulley has a little cover right here. Just take a pocket screwdriver, slap that cover off. Take the bolt, slide it through here. There is a little nub right on the end of the tensioner, of the idler. It's going to line up with the slot in the alternator.

Get that started. I'll just take a 16 millimeter socket and an electric ratchet. You can use a regular ratchet if you don't have an electric one. And again, tighten this down to 30 foot pounds. That's good. Now we can take this cover, put that cover back on. Just like that. I'm going to take the belt, slide it over the crank pulley down below. And then with this other side, go over the power steering pump pulley over there. Then it's going to come around on the tensioner side on the tensioner pulley. Just like that. Go over the water pump. We'll go over the alternator over here, just like this.

And then we want to go below the idler pulley. Now we're going to have to put the socket and ratchet on the tensioner and relieve some of the tension to get that all the way on. So I'm going to take the 16 millimeter socket and the ratchet, and then we need to have this on tighten. So we're going to loosen the tension on this, slide the belt underneath there. Make sure that's all lined up. When that's all lined up, then I can pull this pin out of the tensioner, and let it go. Double check your belt, go around all the pulleys, make sure it didn't pop off, down to the power steering pump or the alternator. It looks good.

It's going to be a little bit easier to install the belt from underneath, so we're going to do that, and just take the belt, slide it over the AC compressor, and slide it over the pulley for the tensioner, and then over the crank pulley. Make sure these are all lined up. That's good. Just like that. Make sure those are good. Take a 16 millimeter socket and a ratchet, slide it into the tensioner, relieve the pressure, and slide this pin out. Or if you used a hex key, pull that hex key up. Double check that. It looks like everything's lined up. I'm good to go. So these have to go on together. Just slide this in position.

Once you get this close, I'm going to start to tighten up the fan. Now these fan blades are, the fan clutch is reverse thread, so it's almost like you're going to be loosening it. There's really no easy way to do this. Just do it carefully to get it started. It's a little bit easier. Make sure the fan shroud is in properly.

That's good. All right. If you have the ability to torque this nut for the fan, you're going to torque that between 22 and 29 foot pounds. I don't really have that ability, so I'm just going to put this tool on there, and just give it a little tap. That should be good. Right here, there's a push pin that's going to go back in here. Slide that in position and lock it down. And on this side, we're going to put this screw right here. And I'm gonna use a T25 and an electric ratchet. Tighten this down, just snug.

I'll position this wiring harness right here, and we'll plug the connector in right here. Lock that in place. Take this piece, slide this into the air box, just like that. And there's retainers right here. Take those push pins and lock them down. Then we can take the negative side. Connect the negative side. Take the same 10 millimeter socket and ratchet, tighten it up. That's good. At this point, if you have that cover, you're going to want to put the cover back where goes.

Thanks for watching. Visit for quality auto parts shipped to your door, the place for DIY auto repair. And if you enjoyed this video, please click the subscribe button.

Tools needed for replacement:

    General Tools

  • Hammer
  • Pick

  • Hex Wrenches

  • 5mm Hex Wrench

  • Pliers, Cutters & misc Wrenches

  • Side Cutters

  • Ratchets & Related

  • Socket Extensions
  • Torque Wrench
  • Ratchet

  • Screwdrivers & Related

  • Flat Blade Screwdriver

  • Sockets - Metric

  • 13mm Socket
  • 16mm Socket
  • 10mm Socket

  • Specialty Tools

  • Trim Tool Set
  • Fan Clutch Wrench

  • Star Drivers & Sockets

  • T25 Socket
  • T20 Socket

2000 - 2000  BMW  323Ci
2001 - 2005  BMW  325Ci
1991 - 1995  BMW  325i
2001 - 2005  BMW  325i
2001 - 2005  BMW  325Xi
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2001 - 2002  BMW  325Ci
2003 - 2003  BMW  325Ci
2001 - 2002  BMW  325i
2003 - 2003  BMW  325i
2001 - 2002  BMW  325Xi
2003 - 2003  BMW  325Xi
1999 - 2000  BMW  328i
2001 - 2002  BMW  330Ci
2003 - 2003  BMW  330Ci
2001 - 2002  BMW  330i
2003 - 2003  BMW  330i
2001 - 2002  BMW  330Xi
2003 - 2003  BMW  330Xi
2001 - 2003  BMW  525i
2001 - 2002  BMW  X5
2003 - 2003  BMW  X5
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