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Adam James

How To Replace Your Serpentine Belt ("S" Belt)

Published in: Automobile, Maintenance and Repair

How to Replace Your Serpentine Belt ("S" Belt)

Before the mid-to-late '80s, most vehicles had a multiple-V-belt accessory-drive configuration, sometimes with as many as five individual belts, which often had to be manually adjusted, separately and in sequence. This system was not only time consuming to manufacture, assemble and service, but also required more room under the hood to accommodate the "staggered formation" required for the accessory mounting locations.

The serpentine (single) belt, also known as the "S-belt," eliminated most if not all of those drawbacks. It's cheaper to produce and easier to service, and also provides packaging advantages at the front of the engine. This system still needs servicing, however. We'll cover when and how to change the belt and its tensioner, as well as other points of inspection associated with this procedure.

When to change the belt depends on a few things but, generally speaking, for optimal performance the S-belt will have to be changed more often than its "V" predecessors. In terms of time and mileage, this would translate to between 30,000 and 60,000 miles, or four years. Under-hood heat, accessory load, the quantity of accessories, and exposure to road debris all affect the longevity of the belt. If the manufacturer specifies a replacement interval, go with that recommendation unless the belt fails inspection at any maintenance interval before then.

When inspecting the belt, if it appears to be glazed (shiny), show cuts, cracks or other deterioration on either side or on the edges, has chunks missing from it, or is merely noisy-it has to be changed. It's helpful if you can determine the cause of a particular problem-from normal wear to damage-so you can be assured that the replacement belt will last the full duration of its service life. We'll touch on related component inspection (necessary especially if the belt failed prematurely) after covering removal of the belt.

Before taking off the belt, check your service manual for any helpful tips that apply to your specific vehicle. One caution: as belt tensioners are sprung very tightly (some tighter than others), any "slips" involving the wrench used to loosen belt tension can cause serious personal injury, as well as damage to the surrounding area under the hood.

Ideally you should use the special service tool designed for belt-tension removal (via the tensioner). Be aware of where the tool will be positioned when tension is removed and make sure the tensioner is resting on its internal "stop." Obviously, if the tool contacts another component before the tensioner stop is contacted, tension is not completely released and the tool will "jam" if left to rest in that position. The possibility of the tool slipping off of the tensioner is high, and injury will likely result.

Once tension is properly released, it's time to remove the belt. Start removal from the most easily accessed and largest pulley having the least amount of belt contact, if possible (sometimes this is the tensioner, sometimes not). Usually, it's just a matter of pulling the belt clear of the other pulleys and right out of the engine bay. However, sometimes engine mounts or other components such as splash shields first need to be removed.

Once the belt is out, here are a few other components to inspect:

  1. Coolant pump for leakage (will cause belt noise if coolant gets on belt) or bad bearing.
  2. Fan Clutch (if equipped) for fluid leakage.
  3. Fan for damage (especially a problem with plastic fans).
  4. Tensioner unit for noisy pulley bearing or wear on tensioner mechanism.
  5. Idler pulley(s) for noisy bearing or irregularly worn belt contact area (especially a problem on plastic pulleys).
  6. Any under hood component that is making contact with or is close to the belt, tensioner, or any pulleys.
  7. Any other source of fluid leakage onto the belt.

With all of that correct, the belt can now be installed. Since all replacement belts are not created equal, get the best quality belt possible. The same cautions highlighted earlier should be observed on reinstallation. Be patient. Route the belt in reverse order of removal, keeping especially vigilant about making sure that the belt ribs are set correctly in the pulley grooves, and the back of the belt is squarely contacting the tensioner and idler pulley(s), before starting the engine.

If applicable, note the tensioner position "scale" (its arrow should be somewhere between the two lines on the other half of the tensioner, preferably on the "tight" side). If it's way off, the belt may be incorrect.

Keep the old belt as a spare in case of emergencies. The only disadvantage of the S-belt is that, if you lose it, all of your accessories are affected. On the whole, however, the S-belt is a definite notch above the old V-type.

Written By
Published: Thu, 19 Sep 2013
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