The first thing to do after diagnosing a bad belt tensioner is to buy a replacement part. You have two options:
- Buy an OEM belt tensioner
- Buy an aftermarket belt tensioner
With OEM belt tensioners, you know exactly what you’re getting. You’re getting an exact replica of the stock belt tensioner in your engine. The question here is: would you get a better deal with an aftermarket belt tensioner?
The clear answer is no. Aftermarket belt tensioners may seem attractive because they don’t cost a lot of money. But the thing is, you’re getting what you’re paid for. Aftermarket belt tensioners aren’t always reliable, and that’s a big deal.
Why Your Belt Tensioner Must Be Reliable At All Times
Image Credit: Nomaallin
The serpentine belt serves a very important purpose. It powers a variety of parts, including the:
- Power steering pump
- Cooling system water pump
- Air conditioning system
The belt tensioner keeps the serpentine belt tight enough to spin the pulleys that power these parts. If your belt tensioner fails, it can’t keep the serpentine belt tight enough. This means a variety of parts will lose power. For example, the alternator will no longer be able to fully charge the battery.
That’s a good reason to never, ever cheap out on a belt tensioner. A good way to ensure that you’re getting a quality replacement belt tensioner is to only buy OEM.
Aftermarket belt tensioners are a hit-or-miss when it comes to quality and reliability. Let’s talk about the main reasons why OEM belt tensioners are better than aftermarket ones:
1. OEM Belt Tensioners Always Have The Correct Dimensions
Like pretty much every other car part (like spark plugs), dimensions matter a whole lot.
A belt tensioner has several different components. Each component needs to be the correct size for the belt tensioner to work with the serpentine belt and other pulleys. For example, the pulley needs to be the right size. If you use a tensioner pulley that’s too big or too small, the serpentine belt won’t be consistently tight. This will lead to some performance issues with the parts powered by the belt.
OEM belt tensioners are exact replicas of the stock belt tensioner in your engine. As long as you get the right OEM belt tensioner for your Mazda engine, you don’t have to worry about any dimension issues. It’s easy to find the right part number for your Mazda engine. All you need to do is look up your Mazda model here.
Aftermarket manufacturers rarely design their belt tensioners to OE specs. If you find one that does, there’s no guarantee that the dimensions are even accurate. Many aftermarket belt tensioners are built with universal dimensions. That’s something you want to avoid while shopping for a replacement belt tensioner.
2. Mazda Uses High Quality Materials To Build Its Belt Tensioners
As long as the engine is on, the belt tensioner is working nonstop. The pulley is spinning, the tensioner spring is keeping the belt tight, and so on. Not to mention, the belt tensioner has to withstand the heat of the engine. That's why it's important to use a belt tensioner that's built with high quality materials.
Mazda always uses high quality materials to build its parts, including belt tensioners. OEM belt tensioners last a long time for that reason.
You can't say the same about aftermarket belt tensioners. A big reason why aftermarket belt tensioners are so cheap is because they're made with low quality materials. If you look on Amazon, you'll find many negative reviews by Mazda owners about aftermarket belt tensioners. We rounded up a few:
- "This [aftermarket] tensioner was on my car for roughly 10 months. I was removing the belt and the tensioner broke right where you put a wrench on it to relive tension. I was holding the wrench in one hand and trying to remove the belt with the other when the tensioner snapped. Luckily my fingers weren't pinched between the belt and a pulley!"
- "[This aftermarket tensioner] was made with cheap aluminum. It broke."
- "I installed [this aftermarket tensioner] and drove about 300 miles. Then it started to rattle."
- [This aftermarket tensioner] is junk. The threads stripped out when I tried to put the belt on. What a waste of money."
3. Mazda Offers A Good Parts And Accessories Warranty
When shopping for a replacement car part, always find one that comes with a warranty. Mazda offers a good parts and accessories warranty on most of its parts. That includes belt tensioners. It's good for 12 months or 12,000 miles, whichever occurs first. You need to buy a tensioner from an authorized dealer (like us) to be able to take advantage of the warranty.
Aftermarket manufacturers rarely warranty their parts. That's another reason why aftermarket belt tensioners are cheap. If you use an aftermarket belt tensioner and it breaks, you'll have no choice but to buy a new one.