What is an accessory belt?
Gasoline or diesel vehicles usually contain several engine accessories that are driven (or turned) by a one or more flexible rubber belts. These accessories include the alternator; water pump; air conditioning compressor; and more. You may have heard your accessory belt referred to as a fan belt; alternator belt; or serpentine belt before. Automotive belts eventually wear out, and need to be replaced.
Your car can’t get very far without your belt-driven accessories, which means a broken or failed belt usually results in a breakdown. The good news is that a worn-out belt is easy to detect, and usually fairly inexpensive maintenance – so this is an easy breakdown to prevent.
Some vehicles also contain a timing belt, which is installed further inside the engine and not discussed in this article.
How often do belts have to be replaced?
Automotive belts are usually replaced based on two factors: their condition, and their age. Condition-related issues are usually detected by a technician during an inspection of your vehicle. (See more on this below.)
Many modern vehicles use newer EPDM belts, which do not crack and deteriorate the way older belts do. These belts last much longer, and don’t show their age as much over time. This means that sometimes, they can break without warning if they are too old. This has led to many car manufacturers now specifying a replacement interval for their accessory belts – usually between 80,000 and 160,000 km. These suggested service intervals can be found in your owner’s manual; or we can look them up for you. When no service interval is available, we recommend replacing most accessory belts every 100,000 km.
Visually inspecting an accessory belt:
Cracked accessory belts:
Many vehicles, including most older vehicles, use a neoprene serpentine belt. These belts lose flexibility over time and crack; eventually breaking. Once a belt becomes excessively cracked (3 cracks per inch is an old industry rule of thumb) then they should be replaced.
A cracked belt can be identified quickly with a brief inspection under the hood.
Worn accessory belts:
As mentioned above, newer EPDM belts don’t crack the way older belts did. Modern belts need to be measured for wear in order to tell if they’re due for replacement. We use a tool called a belt wear gauge to determine how worn the ribs of the belt are.
Once a belt is excessively worn, it starts to generate excess heat that leads to the failure/breakage of the belt. This wear on the ribs is very easy to spot when comparing this old belt (after 100,000 km of use – left side) with a new belt on the right.
Glazed or shiny accessory belts:
A serpentine belt that is shiny looking is referred to as a glazed belt. This glazing happens as the belt is polished from slipping on the pulleys; usually due to a lack of grip from belt wear, or a belt tension problem.
Once a belt glazes, it will usually never grip properly, no matter how tight it is adjusted.
If your car has a glazed belt, the belt tensioner should be examined to make sure it isn’t worn as well. A worn-out tensioner will not keep the belt tight enough, and your new belt will likely glaze again. On vehicles that use manually-adjusted belts (no automatic tensioner), the belt tension will need to be set properly on installation, and then re-checked after a couple months as the belt wears in.
Frayed accessory belts/worn on edges:
Belts that are fraying or coming apart at the edges indicate an alignment problem. This means that one or more of the pulleys are not directly in line with the others, causing the belt to rub on (or ride right off of) the edge of the pulleys. Belt alignment problems are less common on modern vehicles, and are usually caused by one of three issues:
- The serpentine belt tensioner is worn, and the tensioner arm is leaning inwards or outwards (towards or away from the engine).
- The power steering pump has been serviced before, and the pulley was not pressed on to the correct depth.
- The harmonic balancer (crankshaft pulley) is starting to fail, and wobbling as it turns.
Contaminated (fluid soaked) belts:
When your engine has a power steering; engine oil; or coolant leak, your belts can become soaked in the leaking fluid. This causes the belt to deteriorate and fail fairly quickly.
While replacing the contaminated belt will provide a temporary fix, the leaks will have to be diagnosed and repaired in order to provide a permanent solution.
What’s that squealing? Noisy accessory belts:
A serpentine belt that is slipping on the pulleys will cause a high pitched noise that can be described as a chirping or squealing. This noise might only be present immediately after starting the engine, or only when turning the steering wheel. (These are two situations where the load on your belt is higher.) A slipping belt can happen for the following reasons:
- Vehicles with automatic belt tensioners: The belt tensioner may be weak; not keeping the belt tight enough. (Replace the belt tensioner assembly.)
- Vehicles without automatic tensioners: The belts may not be adjusted tightly enough. (Re-adjust belts.)
- The serpentine belt may be aligned incorrectly, and rubbing against the side of one of the pulleys. (Diagnose and repair alignment problem.)
- The serpentine belt may be losing grip due to worn ribs; fluid contamination; or being dried out due to age. (Replace belt.)
Should you spray goop on your belts?
Some drivers looking for a solution to their squealing or noisy belt may come across “belt dressing” products that, when sprayed on a belt, claim to moisturize or condition the belt and stop the squeal. While the idea of a quick and cheap fix is appealing, these products are a bad idea.
The main reason: belt sprays almost never work. Belts only squeal because they are worn out or there is a mechanical problem, and the spray will repair neither of these issues. Even if the spray does stop the noise temporarily, the “fix” might backfire by masking an issue that is soon to cause a breakdown.
The second reason we don’t recommend belt dressing sprays is because in the long term, they actually deteriorate your belts. Plus, they make a mess under the hood and leak into your alternator or other electrical components, where they can cause further damage.
Replacing accessory belts in Airdrie:
For a great quality belt replacement in Airdrie, look no further than My Garage! We’ll do the job right, including using an OEM or premium aftermarket belt that lasts longer, and saves you money in the long run. Plus, we’ll take the time to inspect your pulleys and belt drive components to make sure there are no underlying issues that could shorten the life of your new belt. Plus, our 3 year/100,000 km workmanship warranty – the best in Airdrie – means you can be assured the repair will last.