Article > Tech

Belts Drive More Accessories Than Ever


It used to be that two or three belts drove a few vehicle accessories.

Not anymore. A single belt is now used to run more accessories than ever. And these days, both sides of a belt are being used to drive accessories and that means belts are working harder than ever. It also means they’re important than ever. With this in mind, if a single belt fails, it can be catastrophic.

“Belt noise is like a ‘check engine’ light that something is wrong within the drive system,” said Robert Christy, director of marketing, Dayco Products. “Diagnosing drive noise has become more complicated than ever before because of the complexity of today‘s drive systems and the number of accessories a belt is asked to drive. Many times the belt is the symptom not the cause.”

Accessory drive belts transmit engine torque to an assortment of pulley-driven accessories including the water pump, alternator, power steering, air conditioning and air injection pump. In addition to the effects of high underhood temperatures and atmospheric air pollution, frequent use of the air conditioner compressor, power steering pump or alternator tend to accelerate wear on the drive belts.

Serpentine belts of the past were made with Neoprene and lasted between 50,000 to 80,000 miles. In the past, serpentine belts, which are critical to running all these accessories, were to be replaced when an inspection showed at least four cracks per inch. Other belt issues that required replacement included chunking, rib glazing, and backside wear or splitting.

These days, belts are made with EPDM, or ethylene propylene diene Monomer (M-class) rubber. EPDM belts are extremely resistant to heat, ozone and weather, and as such, can last up to 100,000 miles. But like any belt, they eventually must be replaced.

EPDM belt wear can be more difficult to assess. New EPDM belts will exhibit the typical “V” profile in its ribs. In one that is worn however, the “V” profile will look more like a “U.” This is due to material lost from the rib. Once this happens, there is less material to come in contact with the pulleys, which can lead to slippage. This affects the performance of accessories and causes the tell-tale noise that motorists complain of.

Noise is often the first thing motorists notice about belts when something’s awry. But it’s not always the belt’s fault.
The noise generated from an accessory drive isn’t always caused by the belt itself. It’s a common perception that merely changing a belt will remedy any belt problem. Not so. Belt noise can actually be caused by a number of problems.
If misalignment and tensioning aren’t remedied or the drive isn’t inspected to find the real problem, you’ll often find a customer returning to say the belt is at fault.

There are basically two types of belt noise: chirp and squeal. Both noises mean different things. “Chirp” is generally understood to be a sound that is sharp and intermittent. Chirp can be recognized because as the belt speed increases, the pitch and volume of the chirp remain the same. One cause of chirp is often misalignment between the pulleys on a drive.

There can also be other causes of chirp, such as worn pulley bearings, improper installation and worn ribs. Leaking fluid from other components also can contaminate the belt and lead to the chirping noise.

Squeal, the most commonly heard belt noise, is high-pitched in nature, and can last several seconds. Like chirp, squeal’s pitch does not change, but unlike chirp, its volume can differ. Squeal be both continuous or intermittent. It also can change when the vehicle accelerates or another accessory is turned on (A/C, for example.)
  Previous Comments
avatar   nic   star   6/6/2010   7:12 PM

i go to that thar true value ta get ma belts and they got da best belts eva fer ma car you shold try using dablack ones there more stylish

avatar   Bobby Jay   star   5/30/2010   3:46 PM

I just go to that thar clothing store and get my belts...good will i think is the name...they got the best fashions i've evar saw

avatar   Joe Bob   star   5/30/2010   3:42 PM

I just go to the mens department at the local retail store to buy my belts anyway, the rope ones just aren't very stylish anymore.

avatar   Chris   star   5/27/2010   8:12 AM

Long time no see!

Anyway, I'm probably beating a dead horse here, but I have always preferred the older v-belt system for one reason. If you break a belt, you will lose one accessory. You may not even lose that much if you have a two-belt pulley on said accessory. This will leave you plenty of time to get to a parts house and buy a new belt. If a serpentine belt breaks in the middle of nowhere, you're pretty much screwed unless you've got roadside service.

avatar   tj   star   5/15/2010   1:45 PM

Not always is it the belts or the engines fault. Its sometimes the manufacturer who makes the cars. Like I have a 1993 Dodge dynasty and that is what their mai n problem was was the back of the belt is going across the water pump pulley which is smooth. Well my mechanic thinks he has found a solution which will entail doing a whole new rerouting of the belt by replacing the smooth pully with a grooved pulley and taking the belt underneath. We have placed an email into data and awaiting a reply.

avatar   john c   star   5/13/2010   8:31 PM

Actually newer cars are getting away from many of the belt driven accessories like for instance the 2011 Mustang V6. The only thing the belt drives on that is the alternator and A/C. The water pump is driven off the timing chain and the power steering is an electric motor.

avatar   Billy Bob   star   5/10/2010   12:06 PM

No No No Joe Bob... You gotta use them thar plastic zip ties. That'll get ya done.

avatar   Joe Bob   star   5/8/2010   8:00 PM

Can i use duct tape instead of a belt?

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