In the Nick of Time: Your Car's Serpentine Belt

Michael Walker
Amazines.com
April 18, 2005

Recently, my friend called me from a roadside Dairy Queen in frenzy. His dad had been driving his Ford car down the highway and heard and awful noise. First, there was a squeal and then what sounded like a whip smacking the underneath of his hood. They weren’t sure what was happening, but after investigating, found that a black rubber belt was half-eaten off its pulleys.

“Is the belt still on there?” I asked. “Well, half of it is,” he continued as if the world were ending. “My dad ripped the part that was hanging off and now only half remains!” “Have you driven it? How many miles are on that thing?” I questioned. “Yeah. We drove it into the parking lot here. I think it’s got ninety thousand.” He said flabbergasted.

After a couple more minutes of my friend’s ranting about his dad’s mechanical shortcomings, I took a risk and told them to slowly drive it over to my house (which was only five minutes away).

This problem seems all too common with owners of modern cars. The serpentine belt, both black and cracked, which had half-shredded itself under my friend’s hood should have been replaced long before. The problem could have been prevented.

Before this problem happens to you, you should be sure to check the belts when you do a regular check-up on your car. If you’re a do-it-yourself kind of person, then when you change the oil, be sure that you check the serpentine belt with each and every oil change (or if you use synthetic oil that doesn’t need changed as often, check your belt every 3,000 to 5,000 miles).

The serpentine belt is so called because it looks like a snake as it curves around various drive pulleys. As stated, many modern automobiles have this sort of belt because it’s a lot easier (and less expensive) to install than older “V” belts; plus they last about 50% longer.

A serpentine belt maintains its tension via a spring-loaded pulley. The belt connects to and helps function your alternator, power steering, air conditioning and water pump. You should never break down on the side of the road due to this belt breaking from wear and tear. The problem is easily preventable. Simply check the belt for cracking, fraying or if it looks aged. However, even if the belt looks excellent, it may be time to change it. The time interval will depend upon the recommendation from the manufacturer (see your car's manual), but it’s safe to say that it should be replaced every 60,000 miles, or every two to three years.

If the problem persists and you find yourself having to change the serpentine belt every few months, then it’s another issue. Most likely, there is a problem with the alignment of one of the pulleys. Many times, there could be a problem with what’s called the harmonic balancer. While this sounds nice, this part is located on the front of the crankshaft. It’s made up of an inner steel section, a rubber sleeve, and a pulley with grooves that the belt fits over. If there’s a problem with this, you’ll most definitely have to check to see if it’s in alignment with a straightedge. If you notice it’s not aligned with the other pulleys, then take the car to a professional. They may have to move the entire engine over to work on it.

If you take your car to a mechanic for an oil change, ask about the serpentine belt at that time. Be sure that s/he has inspected all the belts thoroughly. If they recommend changing the belt, be sure that they use a high-quality one. It’s recommended to use the best made, and most likely, the most expensive (usually around 18 to 45 bucks). And, be sure to buy your belt from a respectable auto-parts store as different stores carry different brands and types. Ask your mechanic if they properly dispose of the belt. If it’s some person’s home business, you may want to take the belt to a professional mechanics shop and ask them if they can dispose of it properly. It’s a good idea to keep Mother Nature in tune too! Finally, ask your mechanic if s/he did a test of the belt while the car was in operation.

However, if you’re doing research on a serpentine belt, you’ve already won half the battle. Why not try and change it yourself? If you got some tools and a place to work, then you might feel quite “handy” once you see that it’s not that hard of a job!

First, you’ll want to buy a new high-quality belt. And, be sure to buy a pulley ratchet made for your car. This will allow you to loosen the tension pulley later. So, hopefully your belt hasn’t come off on its own yet. If not, go ahead and draw a little schematic of how the belt goes around each and every pulley. I like to draw it with as much detail as possible. If the belt has already shredded off, then I recommend searching the Internet for a schematic of how the new belt should be placed. It can seem baffling at first. Be sure you find a drawing for the exact date, year and model of your car.

With my friend’s car, we drew a schematic, but still became a bit confused once we had snapped the belt off. So, we went to the Internet for a back-up check.

Next, we took cutters and snapped off the remaining shredded belt. This isn’t recommended. It’s better to locate the tension pulley (the pulley that keeps the belt snug on all the other pulley’s and pumps), take the pulley ratchet and push it counter clockwise. You might have to use another tool (i.e. a hollow bar) for added leverage, as sometimes the tension pulley is difficult to budge. Remove the old belt.

Next, check the old belt and new belt together. Are they the same length? Is there the same amount of grooves on each? If so, continue.

Put the new belt around the other pulleys according to your schematic. Be sure that the grooves in the pulleys match-up to the grooves on the belt. You don’t want it slipping off while driving!

Finally, if the tension pulley is underneath the car, you may have a difficult time holding the pulley loose and putting on the belt. Perhaps there is a friend who could help you. During the aforementioned replacement of my friend’s belt, I held the pulley while he made sure the belt was in-line with the grooves and that it looked good according to our schematic. Now, be sure all fingers are moved out of the way and slowly allow the pulley to draw itself tight again, thereby causing the serpentine belt to tighten around as whole. Check to make sure the belt is aligned on each and every pulley, especially if there are grooves for the belt to fit into. If so, start it up and see if it runs smoothly.

So, instead of ending up on the side of the road in a parking lot at Dairy Queen learning a lesson, check the serpentine belt on your car often.

Michael Walker is a freelance author providing tips and hints on engine related topics such as engines from the JDM, used car motors and swapping engines. His articles are a valuable source of information for the auto enthusiast.