Many drivers are aware of the timing belt in their engine and how is responsible for maintaining the precise synchronization between the camshaft and the crankshaft in the engine to ensure that your engine performs all of its necessary functions exactly on time. As a part of that whole system, a timing belt tensioner is a critical component to ensure that your timing belt is able to do the job it is supposed to do. If your timing belt tensioner fails, your timing belt will also fail and that can cause some serious damage to your engine over the long-term and potentially in the short-term as well.
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What is a Timing Belt Tensioner?
As the name suggests, your timing belt tensioner is there to ensure that the timing belt stays tightly in place as it rotates between the camshaft and the crankshaft in your engine. Because the timing belt is usually made of rubber reinforced with nylon threads to make it durable it is susceptible to wearing out over time including getting stretched out. The tensioner is there two ensure that it stays tightly in place for as long as possible. When the timing belt fails it can cause catastrophic engine damage.
A timing belt tensioner is made of four parts and includes the base, a spring, a pulley, and the tensioner arm. Everything is mounted on the base in the spring is what is used to keep things pulled tightly in place. The pulley allows the belts to move as necessary in the system and the tensioner arm is a counterbalance to the spring allowing the timing belts to move and adjust as necessary. Without the tensioner arm you wouldn't be able to pull the bell tree to replace it with a new one.
Usually we hear of the timing belt itself going bad and needing to be replaced, it's possible that the timing belt tensioner is the problem when your engine and it can be replaced separately from the timing belt if it's not doing his job properly. Of course, if that's the case you need to be mindful of the signs and symptoms that you're experiencing to let you know that it's not necessarily the timing belt that's failing but the timing belt tensioner.
How Long Does a Timing Belt Tensioner Last?
Generally, a timing belt tensioner is replaced alongside the timing belt itself. Timing belts have life spans that can vary greatly from one model of vehicle to another. It's always best to check your owner's manual to find out exactly how long your particular timing belt's last but it's worth noting that in general they are expected to last between 60,000 miles and 100,000 miles.
A timing belt tensioner doesn't specifically have a lifespan that you can look up in your owner's manual or online. They are replaced when they wear out, but there is no suggested scheduled maintenance for a tensioner and it's not the sort of thing that has a specific lifespan.
Theoretically the timing belt tensioner should last the life of your engine. That said, a timing belt tensioner can fail and wear out in time just like anything else does so replacing it as part of a timing belt kit along with the belt itself and the water pump in your vehicle
What Are the Symptoms of a Bad Belt Tensioner?
There are a handful of symptoms you can be on the lookout for to let you know that your timing belt tensioner is failing as opposed to something else in your engine. If you experience one of these it could be potentially something else but if you're experiencing two or more of these symptoms and it's a good sign that your timing belt tensioner is the source of the problem and you should have a mechanic take a look at it as soon as possible.
Knocking Sound
When your timing belt gets loose between gears that it connects to on the camshaft to the crankshaft it can begin to knock between the parts as well as hit the timing belt cover that keeps it secure in place. This sound can either be a steady tapping noise or even a slapping sound. In either case it will be distinct from the normal sounds that are produced in your engine.
The tensioner or the tensioner pulley has failed; it may also cause the pulleys to start making a high-pitched sort of chirping sound. The noise can degrade into a squealing sound if the bearings have completely failed.
Engine Misfires
There are a number of causes of engine misfires in your car however a bad timing belt tensioner can definitely lead to this problem as well. An engine misfire occurs when the valve opens or closes at the wrong time compared to when the Pistons are rising and falling the cylinders and the fuel-air mixture is being injected for the spark to ignite it. If the timing belt is not rotating the camshaft along with the crankshaft at the right time, then your combustion reaction will not be able to occur in that results in a misfire in that particular cylinder at that moment. Not only can this cause a lot of damage over time it will greatly reduce the performance of your engine as well. You can expect poor gas mileage, poor acceleration, and reduced performance overall as a result.
Grinding Noises
If the pulleys aren't being firmly gripped by your timing belt, then the pulley may begin to grind and rattle as a result. If the bearings have gone bad and then you'll definitely hear a sustained and repetitive grinding sound coming from them to let you know that there is a problem.
Engine Won't Start
The crankshaft and camshaft cannot begin to rotate and allow your engine to function properly without a properly tensioned timing belt cycling between them. If your tensioner has failed and then the timing belt is too loose to grip the two gears the result will be neither your camshaft nor your crankshaft is able to rotate at all. That means the valves are unable to open and close, the pistons are not able to rise and your engine will simply not function at all. The starter motor will engage, and you'll be able to hear that, but there will be no starting of the car beyond that. In this particular situation you're going to need it to be towed to a mechanic to get it fixed otherwise you won't be driving anywhere.
Check Engine Light
Because your engine isn't working the way it's supposed to with a loose timing belt and the valves are opening and closing, the pistons aren't rising and such the check engine light will go wash to let you know that there's a problem. Unfortunately, the check engine light can go off for literally hundreds of different reasons so if this is the only symptom that you're experiencing that won't be very helpful in diagnosing the problem for you at all. A check engine light is only an indicator that something needs to be checked out, but it won't really narrow down the potential list of suspects very far.
If the check engine light goes off on your dashboard and you're looking for a little more insight into what the nature of the problem is then your best bet is to use an OBD2 scanner to figure it out. Mechanics use on board diagnostics tools to diagnose a check engine light when it comes on because it will give you a code that greatly Narrows down because of the check engine light in the first place. In this case, if you have a problem with your timing belt, you're going to get a code that should direct you to the timing belt or the tensioner as the source of the problem.
How Much Does It Cost to Replace a Timing Belt Tensioner?
The cost of replacing a timing belt tensioner has a bit of variance to it. You can expect to pay between $350 and $500 to replace a faulty tensioner, but it's also worth remembering that this is usually done alongside the timing belt replacement as well. Getting your timing belt replaced is often a much more expensive job. That can typically run you between $500 to as much as $2,000 depending on the make, model, and year of the car that you're driving.
The reason a timing belt replacement costs so much is that it's a fairly involved and advanced repair job. You have to get deep into the car's engine to access the timing belt and as a result it takes a lot of time and effort to do so. Also, because it's so difficult to reach your timing belt the tensioner will often be replaced at the same time as well as the water pump since they're located all in the same area and it just makes sense to do as much work as possible while you're there. That's part of the reason why the actual cost of this kind of repair can be much more than the projected cost of just getting a timing belt tensioner repaired.
The other thing to remember is that where you get your car repair is just as likely to have an effect on the price as the kind of car that's getting repaired. When you go to a dealership to get this kind of repair job done it's going to cost significantly more than your neighbourhood mechanic will charge. Likewise, if you chose to do it yourself to save on the labour charges then you'd only be paying $50 to $150 on a site like AutoZone for a new tensioner.
Can You Replace Your Own Timing Belt Tensioner?
Doing a timing belt tensioner replacement on your own is not impossible by any means. If you're comfortable doing DIY car repairs that you may be up to the task of doing this job on your own. You need to remember though that getting into your timing belt and the tensioner is definitely an advanced repair job. It takes some considerable skill and effort to do this so if you are new to home car repair you may not want to even attempt this job on your own.
If you do feel confident you can get it done, there are videos that you can find online that show you how to replace the timing belt, the timing tensioners, and the timing pulleys in order to help guide you through this whole process. For the most part, as we said, the timing belt tensioner is usually replaced alongside the timing belt itself. Regardless of whether you're replacing everything or just the tensioner you'll still need to get into the same area so the whole process will take as much effort to get done.
The Bottom Line
The way your timing belt works in your engine is much more complicated than it seems at first glance considering it appears to just be a simple rubber belt. However, every part of your engine including the timing belt needs to be exactly in the right place at the right time for your car to operate. Without the timing belt tensioner then your engine would potentially be completely inoperable and useless since the timing belt can't maintain the synchronized operation of the camshaft to the crankshaft. As simple as the tensioner is, it's clearly an integral part of your engine and without it your car will be completely unable to operate. That reason it's worth respecting this little part and ensuring that it stays in good working order.
If your timing belt fails, the damage to your engine could be severe and end up costing you between $2,000 and $4,000 in repairs, sometimes even more. For that reason, if you ever experienced any of the symptoms of a bad timing belt tensioner that we've mentioned you definitely want to make sure you get in to a mechanic as soon as you can to get the problem inspected and repaired as soon as possible.