Inspecting the Serpentine Belt on Your Automobile

 

 

If you own a late model car made somewhere on earth, you can bet it probably has a serpentine belt. A serpentine belt is a single ribbed belt that drives all the accessories, A/C, Power Steering, alternator and various other pumps and accessories with just one belt. They should require no maintenance unlike belts on older models called the V-Belt that needed periodic adjusting. Even though the serpentine belt requires no maintenance or adjustments as long as it is in good condition they do need to be inspected often to you replace the belt before it reaches the end of its life and leaves you dead on the road. If it starts to go bad, you can replace your serpentine belt at a time of your choosing and not when the belt decides for you. When a serpentine belt brakes, you lose everything, cooling, ac and alternator, you do not want to let this happen. Checking ribbed drive belts at every oil change, and the position of the self-adjusting mechanism indicator, will insure you catch a bad belt long before it snaps.

The backside of the serpentine drive belt, or the smooth side, usually drives the water pump. If the serpentine belt gets oil soaked or glazed, it will slip and not provide the proper circulation to keep the engine cool. And if there is oil on the serpentine belt, it’s coming from somewhere so you will need to find out where and fix it before putting on a new serpentine drive belt.  We suggest calling Pops Auto Electric for help, but do it yourselfer read on.

 

Look for tears or abrasions. If you see any it means the serpentine drive belt is rubbing a pulley flange or bolt as it winds it way around. This will happen more often as the drive belt gets older. If this happens you may need to file a pulley flange smooth or bend something out of the way.  We again recommend a qualified mechanic, for filing engine parts can cause permanent damage if not done correctly.

 

Also look for pinholes and/or bumps. If you see any it means dirt and debris is getting in between the serpentine drive belt and the pulleys. Turn the belt around and see if there are chunks of the ribs missing. You can crank the engine to expose sections of belt as you inspect. A few, small widely spaced chunks are okay, But if there are many and/or close together, replace the serpentine drive belt.  We cannot emphasize strongly enough that inspecting the belt in this manor can endanger your fingers, hundreds of fingers are lost each year but not taking proper safety precautions, do not touch the belt when moving, the groves will grip your fingers and could cause irreparable damage to your person.  Hairline cracks are normal, but if they go into the backing, or flat side, of the serpentine drive belt you will need to replace it.

 

A good rule of thumb for serpentine drive belts is that if cracks are observed 3 mm (1/8 in) apart, all around the belt, the belt may be reaching the end of its serviceable life and should be considered a candidate for changing. Small cracks spaced at greater intervals should not be considered as indicative that the belt needs changing. However, the onset of cracking typically signals that the belt is only about halfway through its usable life.  Remember, using a qualified auto mechanic shop like Pops Auto Electric in Orlando Florida is inexpensive compared to the expense of replacing engine parts and worse case fingers.

 

Insulation of the Serpentine belt in Your Automobile

 

 

Check the tensioner first

 

A “good” tensioner arm should exhibit just a slight vibration with about 1/32 in. or less of arm movement. And the belt should run smoothly with no visible vibration. If the tensioner arm exhibits a jerky vibrating motion, the belt vibrates, or the tensioning arm moves 1/4 in., the tensioner is bad.

 

If your tensioner is bad and it’s one of the more difficult styles to replace, you won’t want to waste your time changing the belt. The shop would just have to remove the belt again to replace the tensioner. So check the tensioner first with these three tests and if it looks like it could be bad contact Pops Auto Electric in Central Florida or a qualified auto repair shop for verification.

 

The first test is a visual inspection with the engine running to assess the dampening feature of the tensioner. Pop the hood, start the engine and turn on the AC. Then shine a light on the belt tensioner and observe the tensioner arm roller for excessive movement (Photo 1). If it passes the visual test, move on to the “crank” test (Photo 2). The tensioner arm should rotate smoothly during crank and release with no binding. If the travel isn’t smooth, replace the entire tensioner. Next, check the condition of the tensioner arm pulley/roller (Photo 3). If the pulley or roller exhibits any roughness, binding or noise, that is also cause to replace the entire tensioner.

 

Many tensioners are readily accessible and attach to the engine with a single bolt. To replace that style, simply remove the belt and then the retaining bolt. Pull off the old tensioner, noting the location of the locking pin on the back. Then slide the new unit into place, lining up the locking pin with the hole in the engine. Hand-tighten the bolt and then tighten it with a torque wrench to the factory specifications shown in your shop manual.

How to tell if you need a new serpentine belt

 

Press the gauge into a belt groove. As long as the gauge sits above the ribs, the belt is good. If it slides down so it’s even with the rib, the belt is worn and must be replaced.

 

First-generation serpentine belts were made from a nitrile compound that cracked with use. If your belt has cracks in three or more adjacent ribs within a 1-in. span, or has four or more cracks per inch on a single rib, it’s time to replace it. You also need a new belt if you notice any of these conditions: chunks missing from the rib area, torn or frayed fabric, glazing on the belt’s back side or debris trapped in the ribs.

 

Starting with the 2000 models, carmakers switched from nitrile to ethylene propylene diene monomer (EPDM) belts. EPDM belts last much longer and don’t crack or lose chunks the way nitrile belts do. But they do wear, and that wear is much harder to detect. You can measure EPDM belt wear with a gauge or a smartphone app. Both products are available for free from Gates Corp. (go to gatesprograms.com/beltwear and click on either tool).

 

In most cases, you’ll want to use the plastic gauge to measure your belt, as shown above. However, if you have a smartphone and enough maneuvering room to shoot a close-up photo (engine off), let technology do the work for you. The app works by analyzing the width of the ribs compared with the width of the grooves.

 

Always buy premium belts instead of economy grade — you’ll get almost twice the mileage.

 

 

 

The right tools make it a do-it-yourself project

 

 

Examine the decal that shows the belt routing. If yours doesn’t have one, draw one before you start the job.

 

You can replace a serpentine belt with ordinary hand tools. But we don’t recommend it. The spaces are often tight and the belt-driven devices difficult to reach. Using a serpentine belt tool to loosen the tensioner and a belt placement tool to position the belt, we completed the entire job in less than 15 minutes, without breaking a sweat (or a knuckle). The serpentine belt tool comes with an assortment of sockets, making it the perfect choice for all the cars in your family. The two extension bars can be configured to reach the tensioner at the proper angle, and the extra-long handle provides maximum leverage so you can release the pressure easily. The belt placement tool allowed us to remove and properly place the new belt without reaching down into the pulley area.

 

Note: If your car requires the removal of an engine mount in order to remove the serpentine belt, or the belt’s just nearly impossible to get at, we recommend you leave the job to a professional.

 

Want to make this problem go away with one simple phone call?

 

Address:

 

Pops Auto Electric & AC 

4704 S. Orange Ave 

Orlando, FL 32806

 

Phone:

407.857.8579 

407.420.1244

 

Fax:

407.857.6535