Thursday, August 25, 2011

Why You Should Check Your Serpentine Belt for Wear

I'm pretty fanatical about caring for my cars, in case you haven't noticed yet. The Range Rover recently was put back in service after a complete brake overhaul. Before driving it again,  I gave it a fairly thorough inspection because it has sat nearly all summer. Everything was passing with flying colors. 

And then, I found this.

That's an "epic fail" in the Belts and Hoses department.

I guess I just hadn't taken the time to examine my serpentine belt lately, despite being obsessive about doing 3,000 mile synthetic oil changes, flushing the coolant, and all that other fancy stuff. So it's fortunate that I noticed this before the belt snapped and beat up the rest of the engine compartment.

Serpentine belts are precisely designed to fit your vehicle. Yeah, Some Japanese or German dude spent six years bent over a desk, trying to figure out if a 700mm belt was better than a 700.05mm belt.

And they are indeed critical, seeing as they operate a large number of accessories that usually include power steering, the water pump,  the air conditioning compressor, and on some older cars, the cooling fan. Basically, if this belt breaks, you're totally screwed. Yes, you'll have to give up your pride and call the number on that AAA card your grandma bought for you last Christmas.

Here's how to inspect a serpentine belt for wear. It's not rocket science, but it's important!:

Unlike their V-Belt grandparents, serpentine belts don't need adjustment over time. Once they slip or squeak, they will need to be replaced. Don't even think about using that Belt Dressing crap: if you do, you'll spend at least 46 years cleaning the gummy residue off your pulleys so your new belt stops slipping.

Most serpentine belts have one grooved side, and one smooth side. Exceptions include some Volvo belts, select VW belts, and some Chrysler minivans, which have grooves on both sides of the belt.

The back (smooth) side usually runs along the tensioner, which keeps the belt tight, as well as an idler pulley, which is just a dead pulley that gives the belt something to hold onto. On some cars, the water pump is also driven by the backside of the belt. The back side usually won't show wear, but if it is brown in color or if there's cord (fabric) showing, the belt is definitely trashed. This is where people go wrong: They see that the back smooth side of the belt doesn't look "worn," when in reality it usually won't look worn before the belt snaps.

Look at the grooved side of the belt. This is where you need to inspect carefully. Surefire signs of imminent failure are cracks that are spaced closer than 1/8th of an inch apart. A crack that spans the entire belt, like the one shown above, means that you definitely need to get a new belt ASAP. That's your belt saying "Hey, cheapass, I'm ready to retire, so get me a replacement before I walk out on my own!"

Cracks that are spaced fairly far apart aren't a big deal, but this is a worn out belt for sure. I'm rather embarrassed to admit it came off one of my cars...

Replacing your belt is pretty easy: on most cars, it can be done in under 15 minutes. I find serpentines easier than V-belts, because you don't have to mess around with the tension for half an hour, arguing with yourself between what's too tight, what's too loose, etc.

- Find the tensioner. It'll look like a metal arm with a pulley on the end. Use a ratchet to pull it down and release the tension. You may want to use a breaker bar, the tensioner springs can exert a lot of force.

- While holding the tensioner "open," remove the belt.

- Compare the old belt to the new one, paying attention to the length of the belt and the number of grooves. "Close enough" isn't close enough with serpentine belts- half an inch can make or break your engine accessories, quite literally. If it's wrong, take it back and get the correct belt.

- If the pulleys are dirty, brush them off before you put the new belt on. 

- Many cars have a sticker that shows the belt routing. Study it for a quick second and then put your new belt on, referring back to the sticker as needed. I like to save the largest, most accessible pulley for last. You should never need to pry a new belt over a pulley: this would indicate that you got the wrong size belt. But they do often require "gentle persuasion," and it's easier to work with a large pulley at the top of the motor than a little one at the bottom.

If your car doesn't have a belt routing sticker, Google it, look in your owner's manual, or check out this handy guide. (heads up: it's a large PDF file)

- Last but definitely not least. Carefully examine the belt. Look on every angle of every pulley. Use a flashlight if you need to. Make sure the belt is properly seated on all pulleys! It is very easy to seat the belt incorrectly on just one pulley, with one groove hanging over the edge. If you don't see this, it can have bad consequences, like shredding your new belt and hitting your hood, fan, etc... taking your pride along with it!

- Start the car. Enjoy your peace of mind and the satisfaction of averting a major motoring crisis.

That's all for now. Go check your belts.

Ad opens in new window:

The Rover says "hello," and it loves its new belt.

1 comment:

Your comments are welcomed and encouraged! Unless they're spam, of course.