Pulley Problems Diagnose Noise Under Your Truck Cars Hood

Hey, friends, it's Len here, from 1A Auto. Today we want to talk to you about some of the common problems that you might find with pulleys on your engine. Let's get into it.

Okay, so we got everything out of the way so you have a nice, clear view of all the pulleys on your belt system here. Different vehicles are going to look a little bit different, but they're gonna be approximately the same. They're gonna have an alternator, more than likely, an idler pulley, a tensioner, maybe an AC compressor. Essentially, we just kind of want to go over some of the pulleys.

To check your pulleys, it's best to remove your serpentine belt. So now, if we look at the idler pulley right here, you're gonna see it's supposed to be a smooth surface, but this is actually rusted and rotted, and it's actually kind of building up some kind of crud on here. What that's gonna do is it's going to rub along the backside of the belt here, and it's gonna wear into it. It's gonna cause premature wear on your serpentine belt. So something that looks like this, well, either you'd want to clean it up. You can use a little bit of sandpaper and try to clean it up so it looks pretty. That will probably be pretty temporary. Or, of course, you can replace it if your pulley looks like this. Other pulleys aren't smooth like this one. You might notice that this alternator right here has a ribbed edge. The ribbed edge of the alternator is gonna go right inside the ribbed edge of your serpentine belt. If, for some reason, it's rusted and rotted inside there, of course, it's gonna cause the same issue with the belt, and you're gonna hear noises.

Okay, so we talked about the looks of the pulleys themselves. Yeah, they might look a little bit, you know, dirty and stuff like that. That's one thing to look for. Other things to look for is something that you'd have to remove the belt for so you can test. If you were to grab onto your pulley and try to wiggle it, and you see it moves like this, or maybe even just a little bit less, that's obviously very bad. As your belt's going around and around rotating, this is gonna be chattering, and it could potentially throw your belt off into your fan and cause a major issue. If your pulley moves around like this, obviously, the bearing is very bad. If your pulley moves like this, which is very slight, that's actually normal. It's supposed to do that a little bit. That's a good thing, okay? So that's good, this is bad.

Now, when we were checking the bearings on the pulleys, we saw that this one was moving around, so that meant that it was loose. Another way that you can tell if your bearings are no good, is you can try to just give them a spin. If you find that the pulley just keeps spinning and spinning and spinning and spinning for days like that, then that means that your bearing on the inside is actually worn, there isn't the grease inside there that needs to be, and more than likely, while this is under pressure and spinning around at the specific RPMs that your engine's running, it's going to be making some noise inside there. Something else to think about is not only can your bearings be loose to the point that they just spin and spin, but you might also find if you try to grab onto that pulley and give it a spin, it just doesn't want to. It's actually binding up inside the area where the bearing's supposed to be. Right here is the bearing area of your pulley. The center area right there is supposed to be able to stay still, and then the outer portion should be able to spin on the bearings that are located inside of the unit. This is the original one, and it really just feels like it's binding up. It has some spots where it seems like it wants to spin, and then it just kinda stops, and then it spins, and then it stops. Let's get this off of here, put on the new, so you can see what it's supposed to look like.

Okay. Let's give this a little spin. So, as you can tell, this goes around, no problem. There's no resistance, but it also doesn't just keep spinning, and spinning, and spinning, and spinning on its own. That tells me that the bearing is in good condition.

Some of the pulleys that you're gonna want to test might be attached to something like your alternator or your power steering pump, or even your water pump or AC. With those, the bearings are actually gonna be located internally, so it's not necessarily something you'll be able to see, but if you were to just kind of try to grab onto it, and wiggle it up and down, maybe in and out, and then also try to give it a spin, if it seems as though it's binding in any way, obviously that's gonna be an issue. You either have to rebuild, which is gonna be a lot of work, in which case you'd have to replace the unit.

Now, another way that you can test your pulley bearings, is to take a nice long pry bar that looks like this, or even a long screwdriver. You start the vehicle, and you be very careful, because your belt system is gonna be spinning around. Make sure you're wearing eye protection and hand protection. We're gonna take the bar and we're gonna go as close to the pulley as possible without actually touching it. That's gonna be approximately where the bearing's gonna be. And then I'm gonna just give it a little listen. You're gonna hear a little bit of noise no matter what because there are bearings in there and they're gonna make some noise, but if you hear a loud screeching noise, or anything like that, you know that that's no good. You can do that. You can move yourself around. When you go to the tensioner, it's gonna be a little bit harder, because you'll notice that the tensioner moves up and down. So if I was to try to put my bar on there, it's gonna just jump around. I can try to listen, but all I hear is, tap, tap, tap, tap, tap, tap, tap. You can try it with your idler pulley, just go right to that bolt in the center if you wanted to, but be very careful for the fan. Everything that we're talking about right now is you have to keep safety as your number one concern, okay? This is kind of a last thing that you'd wanna try, but it does work.

Now, some of the noises that you might hear, whether you have a bearing that's starting to stick on the inside of the pulley, or even a loose bearing, where it just keeps spinning and spinning, spinning, or even just your pulley is in poor condition, you might start hearing a little bit of a chirping noise, which you might kind of associate with a serpentine belt, it could actually just be from the pulley itself. You might hear a squealing noise coming from the bearing, because it's seizing up and it's overheating. You might also hear a chattering noise. More than likely, that's gonna be due to the fact that either the bearing's completely seized up, or it's very loose to the point where the pulley can move around and it's causing that chattering noise, okay? As the serpentine belt's going around and round and round, it's going around the pulleys, of course, and it's spinning those bearings on the inside. If they're seizing up, or even if they're loose, it's gonna cause an issue.

Okay, friends. So we tried to make an educational video for you about pulley bearings. Hopefully, you learned a little bit of something along the way. If you did, and you want to talk about it, leave it in the comment section below. While you're at it, if you like the video, make sure you smash on that like button for me. It would mean the world. While I still got you here, why don't you go ahead and subscribe and ring the bell. That way you can be kept up with all of our latest content. Thanks.

Thanks for watching. If you want the parts to do it yourself, check out 1aauto.com, the place for DIY auto repair.