'02 Olds Alero Serpentine Belt Replacement - DIY or $120?

Location: South Jersey.
Vehicle: 2002 V6 Oldsmobile Alero. 165,000 miles. Single owner. I drive it often, but my wife is primary driver.

It has a belt that is whirring (but not screeching) since it’s gotten cold. I haven’t visually inspected if it’s cracked, rotted, etc. My wife brought it in for an oil change and asked them to determine the cause of the whirring. She may have mentioned that I heard it from the belt area. We brought to a nation chain - Monro, if that makes any difference.

They diagnosed it as a worn belt. I’ll inspect tonight, but it seems like a reasonable diagnosis to me. Does this sound reasonable to you?

Next question… How difficult is a DIY replacement? I can change my own oil. I’ve changed my own brake pads before. In my youth, I owned an 86 Chevy Celebrity which infamously ate through belts. I could replace that one with my eyes closed… but it wasn’t a serpentine belt, and it was many years ago when my time was worth considerably less and my money much scarcer. I can build & fix a lot of things, but I’ve never really been much of a car guy. With cars, I tend to need them and the chance that I can’t do the repair in a timely manner is usually enough to persuade me to pay someone to do it for me.

The shop wants $120 to replace the belt. That seems ridiculously high to me. I’m worried that I’m remembering replacing the belt in the Chevy for< $20. The priciest serpentine belt (for this vehicle) is listed as $33 at Advance Auto Parts. If this is something I can reasonably do in an hour or two, I’d like to save the $90. If I’m going to have to buy $50 worth of tools or the tensioner is impossible to reach for a driveway mechanic, I’ll pay someone.

Whirring is not a typical symptom of a faulty belt, however I have seen belts make various noises that one would not at first ascribe to a belt. So it could be the belt, but I’d use a stethoscope or listening stick on all the pulleys before removing the belt, and spin all the pulleys by hand after removing it, to see if something else is causing noise.

The price is in line for serpentine belt replacement. This type of belt is much longer than a typical V-belt, and of a more sophisticated construction. The price you pay at an auto parts store is very close to the wholesale price the shop pays at the same store, but of course the shop is a business and will mark it up to a retail price. (And please don’t buy the belt and ask the shop to install it.)

On this engine, it looks like the only tool required is a 3/8" breaker bar (flex handle), and I expect you could do the replacement yourself. First, look for a sticker under the hood with a diagram of the belt routing. If you don’t see one, draw such a diagram yourself. There’s a square hole in the belt tensioner arm; fit the breaker bar into it and rotate the tensioner (counterclockwise on this one) to relieve tension and remove the belt. Thread the belt onto the various pulleys as per the diagram, going for the power steering pulley last. Rotate the tensioner to install it onto the last pulley, then let the tensioner go to set itself. Check that the belt ribs are properly mated to the grooves in all the pulleys, and you’re done.

The most difficult aspect is reaching down to some of the less accessible pulleys to get the belt properly mated on them (there are even special tools to facilitate this, but usually a way can be found without them). The tensioner is spring-loaded; it should move with reasonable effort on the breaker bar and spring back into place when let go. If it doesn’t move properly, a new tensioner is called for. The tensioner is held on with one bolt and replacement is pretty straightforward; note that it will have some sort of indexing tab which must be aligned with a slot.

ETA: If no further problems are found and you don’t run into major frustration placing the belt onto the pulleys, the working time should be much less than an hour.

Thanks Gary. That was an excellent description and gives me the confidence I need to tackle the project. My searches brought up the occassional person saying they needed to jack up the engine and remove a couple mounting bolts. I’m glad to see that’s a ridiculous as it sounds.

I’ve got my Haynes manual. I’ve got the diagram on the car. I’ll also take a picture, and I should be all set.

And before I call it a day, I’ll check the pulleys. You mentioned checking them listening to them. What should I be listening and looking for? Cracks? Loose pulleys? Small rodents?

Thanks again!

One more bit of advice, don’t try to be Superman when you pull back on the tensioner. It will move a little and stop, don’t pry further. I bent one once and ended up replacing the tensioner arm too because the belt won’t stay on a misaligned tensioner.

With a whirring sound, there’s a suspicion that a pulley bearing may be on its way out. With the belt on and engine running, place the tip of a mechanic’s stethoscope or listening stick (long thin metal rod – a long-shanked screwdriver works well) onto a non-rotating bolt or housing as close to the center of each pulley as possible. BE CAREFUL NOT TO PLACE THE TIP ONTO A MOVING PART – IT WILL BE JERKED OR FLUNG AND MAY CAUSE INJURY. With your ear at the other end, compare the sounds among the various pulleys. A certain amount of whirring noise is normal, but if one sounds rough/rumbly/grindy or a lot louder than the others, that indicates a problem.

With the belt off, most of the pulleys should spin easily by hand and be fairly smooth and quiet. Of course the crank pulley won’t turn (it’s not a concern), and the power steering pulley won’t spin freely without your hand moving it, but if you hear significant noise or feel roughness that indicates a problem.

It’s not uncommon to find faulty idler pulley bearings and tensioner pulley bearings. Idler pulleys with bearings are a common replacement part; tensioner pulleys w/ bearings are separately available for most cars (assuming the tensioner is otherwise okay). Roughness in an alternator, power steering, A/C compressor clutch, or water pump pulley requires replacement of the whole unit.

I have run across some GM engines that require removing an engine mount to replace the belt (stupid design, but it exists). However, my repair info for your engine makes no mention of this, so it shouldn’t be necessary.

It’s a one beer job on a scale from 1-10. Keep your old belt and a cheapie 3/8" drive socket wrench in in the trunk in case, you throw the new one or it breaks.

Even if the noise persists, it is a cheap piece of preventative maintenance on an engine with 165k.

If it makes any difference, I can describe it better than just “whirring.” You know when your stereo picks up interference and you can hear it correlate to engine speed? It almost sounds like that, but really loud; yet not so loud as to make bystanders turn their heads.

I’m not looking for more information really; I just wanted to offer that up in case it made any difference in your suspicions.

Understood; it doesn’t.

Bolding mine

Can I hijack just for a second and ask about the bolded statement? Is buying a part then asking a shop to replace it merely a breach of etiquette or something more?

I only ask because, while I don’t do this myself, my roommate is constantly having to replace crap on his VW (he delivers pizza 6 days a week). I asked my cousin, a VW mechanic, about the price the roommate was quoted for a fuel pump at a local shop. Cousin said the price was in line but perhaps roomie should check out the web site of a shop where he used to work that sells OEM VW parts for a great price. We found the part and it was $450 lower than what the shop quoted. Being that he’s a poor guy, roomie is hoping to buy the part from the other place and hire the shop to install it.

I suspect your answer will be “does roomie know exactly what part he needs? If not, that’s why he shouldn’t do it” … or maybe “that’s just a dick move”?

It’s that a shop needs to make X dollars. They could choose to give the parts away at cost and then increase the labor costs. But then they couldn’t be competitive in mostly-labor jobs. The balance the shop chooses between parts mark up and labor is probably correlated to market demands and the actual costs of maintaining an inventory and/or parts supply staff/gophers.

Bringing in your own parts without negotiating that upfront will just make the manager less apt to help if something were to go wrong. There are plenty of shops that will let you bring in your own parts; just be upfront about it so that they can be equally upfront with pricing. On the surface, this isn’t going to get you the best deal. But what’s a happy mechanic worth?

At least that’s always been my take on it.

I only bring it to a chain because I haven’t been able to get a good recommendation for a close mechanic, and it’s usually my wife that’s bring in the car (which is relevant, because the national shop we use is adjacent to Sam’s Club and Starbucks).

It’s essentially what JerseyFrank has said. Traditionally, repair shops have made some of their profit on labor and some of it on parts, and most shops still structure their pricing along those lines. While that pricing model remains, the auto parts market has changed to where the general public can buy parts at pretty close to a shop’s wholesale price.

It’s only natural that people don’t want to pay full retail for parts if they don’t have to, so it seems to make sense to buy the parts at an attractive price and just pay the shop’s labor to replace them. This leaves the shop with three choices: refuse to do that, do that but adjust the labor from a “we supply the parts” level to a “you supply the parts” level, or do that for their “we supply the parts” price and miss out on their normal profit. The first choice doesn’t satisfy anyone, the second may be resented by the customer, and the third will be resented by the shop.

The root of it is that auto repair is typically priced on the assumption that the shop will supply all that is needed, and the breakdown between parts and labor is done for accounting purposes rather than with the intent that either component will be sold separately at its proportion of the combination price. Asking for labor only at that combination-based rate breaks that assumption.

Some shops will do the labor-only job at the lower rate, but grudgingly. It’s not a good business model. Refusing the job avoids the problems (see below), but doesn’t help the business any either. Taking the job at a higher labor rate can avoid the loss of profit, but does present other difficulties.

If the shop doesn’t supply the parts, it can sometimes be a bad situation for the customer and the shop. It may be the wrong part, giving rise to delays (sometimes with a car disabled tying up a stall) and the problem of who’s going to supply the right part, and how soon. If the part happens to be faulty, it’s not the shop’s responsibility, so the customer would have to pay the labor a second time to replace it. In a worst case for the customer, he’s caught in the middle of a shop that insists it’s a faulty part that they installed properly and a parts supplier that insists it was a good part that was damaged by improper installation – no warranty from anyone. In a worst case for the shop, the dispute goes to court where a judge deems the shop experts who should have been able to tell the part was faulty (though they never say how to achieve this miracle) and the shop is stuck with providing warranty for something they didn’t even sell in the first place.

An imperfect but often used, and often helpful, analogy is bringing your own food to a restaurant so as to get a discount on the meal. If that steak is tough, was it a bad piece of meat or did the cook botch it up? If you get sick, was it previously contaminated food or an unclean kitchen? Who’s responsible for the customer’s dissatisfaction?

Most of the better shops will generally discourage customer’s supplying parts, but will consider going along with it on a case by case basis. Factors involved include whether it’s a regular customer, the potential risk to the shop, specialty parts that the shop’s regular sources might not provide, etc.

So while it’s not necessarily a “dick move” in the sense that the customer is intending to hurt the shop in any way, it can be “dicky” for the shop nonetheless. My recommendation is to let the shop provide the whole job, and that way the shop can guarantee the whole job.

Thanks for your answers, guys. All clear!

Canada here

I replaced my serpentine belt on an 02 sunfire for cost of the belt which was 25 bucks. It took me roughly 2 hour or so , simply cause I had never done it before. One of the reasons that it took so long was that I removed the old belt and its still sitting in the trunk as I type this.

If your belt is that bad , simply cut it off instead of playing nice with it like I did. Once you follow the diagram for how the belt loop around the different pulleys , the final pulley will be the tricky part. Make sure that if your doing it solo , that you have a really long screwdriver to flick the belt over the last pulley. The tensioner will take up the slack and your good to go.

The Alero might have a larger or smaller engine bay than my sunfire , so if you can get at the belt easily it should not be a big deal. One thing that I was advised to do was to disconnect the battery, to ensure that no premature engine start would occur should you drop that screw driver or what ever and it crosses something.


I will respectfully disagree with some of this advice.

In my experience, removing the old belt is the easiest part of the job. I really don’t see much point in cutting it off. I will grant that on some applications, there is very little space between a low-lying pulley and the car’s body to where the belt has to be twisted sideways to get it out, and it that case it would be quicker to cut it and just pull it out. However, the new belt would still have to be twisted to get it on.

While I have found long-reach tools can be handy in positioning the belt onto low-lying pulleys, I never use one to get it onto the final pulley. Part of the technique is to choose a final pulley that is accessible, and I find it easier to put the belt onto it by hand.

Offhand, I can’t think of any design where a dropped tool has any likelihood of engaging the starter. Many factory instructions are overly cautious in advising to disconnect the battery when doing certain jobs, but I don’t recall any that say to do so for a belt replacement.

Just wanted to pop in and mention that my '99 Alero has a similar issue and that my mechanic diagnosed the noise as a worn AC Compressor clutch. He quoted something like $400-$450 to replace the AC Compressor. I’ve decided to just deal with the noise for the time being because the AC still works fine and it’s the middle of winter so listening to the noise isn’t really an issue with the windows closed.

One easy way to test to see if your noise is associated with the AC Compressor Clutch is to turn on the engine so that the noise is occurring and then engage the AC, if it’s a Clutch issue the noise should stop when the AC is engaged.

I’m not sure if there are any similar tests that don’t require a listening tool, but I doubt it. Maybe a power steering pump’s noise characteristic would change when the wheel was turned, but on the off chance that the AC Compressor Clutch is a common issue with Aleros’ I figured a second data point might be useful.

It was two things really , one was the accidental start, that I did not think was possible anymore and the other was to make sure that no one could start your car the conventional way. Mine is a single driver vehicle , so I did not think anyone would try, but accidents do happen for stupid reasons sometimes.


… from what I’ve seen around here, if the labor time is much more than maybe 10minutes, you’ll get billed for an hour. It’s reckoned the other way around, though – most repairs have an hour of labor built in, but if its something super-quick, the shop will “eat” the labor cost.

I am not an auto mechanic but I am a computer mechanic :smiley:

This is pretty much spot on. The other sad thing about it is, the type of people who would want to shave off a few dollars buying their own parts are also the same type of people who come back with other problems that they don’t want to pay full price for. I run my shop along a similar model, my labor is cheap, parts are a little more pricey than average. If you come in with parts and there is a problem you can easily go from saving $20 in parts to paying another $50 in labor if there is a problem with the part. Like auto parts you can hunt for the best deal on every part online but most people are not interested in waiting 4 days for free ground shipping from newegg to save a few dollars. Also why should we go to the time and effort to have the parts on hand if you don’t want to pay us for it.

Think of parts markup as being charged for the labor to order, process, store, and costs to warranty the labor on installing a part. It makes a little more sense that way.

Good point, and that’s just how many auto repair businesses look at it.

Just an update: I paid the $120 + $11.99 “shop supply fee” :mad:

I would’ve had to remove 2 engine mounts to slide the belt off. That + cold + inadequate garage space (because I can’t seem to complete a project) + needing to drive to Boston = a good deal… except the shop fee. Total horseshit.