How to Replace Serpentine Belt Tensioner with Pulley 2002-10 Mercury Mountaineer 4-6L V8

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Hi, I'm Mike from 1A Auto. I hope this how-to video helps you out, and next time you need parts for your vehicle, think of 1AAuto.com. Thanks!

In this video, we're going to show you how to replace the serpentine belt tensioner on this 2003 Mercury Mountaineer with the 4.6-liter V8 engine. It's the same part and similar process on most of the Ford, Lincoln, and Mercury trucks that have this same engine. The items that you'll need for this include a new serpentine belt tensioner from 1AAuto.com, 1/2 inch socket bar or ratchet and pipe, long screwdriver, 10mm socket and ratchet, and a torque wrench.

The easiest way to get to your tensioner is from underneath. It's right up here, you just take a 1/2 inch ratchet and push it into that square hole on your tensioner. Using a pipe for extra leverage, it makes this a lot easier. You just pull back, release the tension on the belt, and you can pull it free from this pulley. Then when you release the tension on the ratchet, you actually have to take the fan and make sure it doesn't get caught on the wrong side of the handle. Pull it out like that and then pull your ratchet out.

Now I'm going to reach down, and pull the belt off of the pulley where we already loosened it up, and then you can pull this up and out. You've just got to be careful not to get it caught on the fan too much. I'm going to reach way down on this side and I'm going to put my hand in there like that. I can feel the belt and I can pull it up off the pulley that's down here which is if you look on the diagram, I'm pulling it off of this pulley here and while I'm pulling it off of that pulley, I'm going to pull up on the belt because you have to basically pull it right in between this space here. I'm just guiding it up through there. Now the only place it's on here is the big crank pulley. Again, I'm just reaching down and I just have a hold of the belt right here, I'm pulling it out away from the engine to try and get it off of the crank pulley. If I can reach down in here I could pull it out from the crank pulley, pull it out from the water pump, and then just pull the whole thing right up and out.

Now you want to remove these three 10mm bolts on your serpentine belt tensioner. We'll fast-forward as Mike does this. You may realize that we've disconnected that radiator hose, but you don't need to do that, that was just for shooting purposes. Once you remove those bolts, you can just pull that tensioner up and out.

Up top is the old serpentine belt tensioner; below it is the new one from 1A Auto. You can see they're identical, and they'll fit exactly the same.

Take your new serpentine belt tensioner and feed it down into place. You want to find a gap in the fan blades, some of the gaps are slightly larger in between each blade. You want to find one of the larger gaps, feed the tensioner down in, and then once you've got it somewhat lined up start feeding the bolts in and just get them started, each one by hand. We'll just fast-forward as Mike tightens all those up. Now torque all three of those to 30 foot-pounds.

To reinstall your new belt, what you want to do is put a loop down around the crank first and get it lined up on your water pump. then you basically have to kind of jam a loop right down in between your tensioner, down to this pulley, and then you can line everything else up. First, we'll take it and we'll put the loop down between the fan and the water pump pulley for the crank. It's almost like you're lassoing the crank a little bit. You reach way down in there and grab the belt with your other hand and flip it around the crank. Going underneath this pulley here, you can see the belt right there. I just got to get it pushed on the crank and guide it with my hand and pull it up and around. It's on the crank. The back side that comes up, the belt that comes up from this side of the crank. You got to push in and push it around your water pump pulley and push this loop, you push this loop down onto that side for right now. We're not going to worry about it too much. The harder part is taking this part of the belt right here. Once you have it down and around the crank and pull it up.

Then you just want to take. You probably can't see my fingers, but I'm just pushing it between the idler pulley and the pulley underneath. Just take a long screwdriver and push it right down through there. Now if you want to reach up from the bottom, grab that belt, pull it through, and put it down around your A/C compressor here. Now from up here, I'm just going to pull that tight around that A/C compressor pulley. I'm reaching down with this hand and making sure it's on there correctly. Then I'll put this, this has to go down now around this idler pulley, and push it down, and it's somewhat ready to go around these two pulleys here. Basically, I've got my belt, I've put it first down around the crank pulley, and then I went down around the A/C pulley. Now it's on the alternator, it's underneath this idler pulley, and when I pull my tensioner, I'll put it around these two pulleys the rest of the way.

A quick check and see it's on the crank correctly. It's really not on this A/C pulley correctly, so I'm going to lightly pull on it and get it on around there correctly. After I do that I'm going to reach up in here and pull on the belt a little more, that will tighten it up. I'm going to use a flexible bar and basically, what you want to try and do is slide the bar up in there and just try to feed it in. You'll have to push out against the fan as you're feeding this in and get it to go into the tensioner. You want to have it at just a little bit of an angle, not straight up and down, angle it, feed it up in, and you really have to push back against the fan and force the part in there. Get on there and now I can pull that as far as I can. Reach up on this side, put the belt on, make sure the belt is on the power steering pulley.

From down here, we've got the belt on there correctly. It's on my crank pulley correctly and it's on this one correctly. This is the one that I fed it onto right here. I'll take the wrench off and, again, you have to push back against the fan some. Actually my fan's caught. I'm going to pull it. Make sure you feed the fan underneath and out. Now from the topside, you can see it's on the alternator correctly and it's on these idler pulleys and the water pump correctly.

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