Symptoms Of Timing Belt Tensioner Failure

Some timing belt tensioners last a long time. Others don’t last all that long. Usually, the tensioner is replaced along with the timing belt. When a timing belt tensioner fails, it loses tension. As a result, the timing belt becomes loose, and the valve timing can be thrown off. This leads to engine performance issues.

So, if any suspicion arises that the timing belt tensioner has failed, it’s important to check the tensioner and replace it if necessary.

Causes Of Timing Belt Tensioner Failure


The most common causes of timing belt tensioner failure include:

  • Wear and tear: On a new mechanical timing belt tensioner system, the timing belt tensioner spring is wound tightly by two tension rods. Over time, the spring stretches out and loses its tension. As a result, the entire tensioner becomes too weak.
  • Dirt and dust build-up on the timing belt tensioner pulley: When this happens, the pulley will fail to support the timing belt. It may cause the timing belt to slip off.
  • Hydraulic oil leak: A hydraulic timing belt tensioner assembly works like a small shock absorber. It uses hydraulic oil to maintain the tension. If the timing belt tensioner is leaking, it will lose the tension it needs to keep the timing belt tight.

Signs Of Timing Belt Tensioner Failure

belt tensioner

There are several different ways to detect timing belt tensioner failure simply by driving the vehicle. One thing to keep in mind is that when the tensioner begins to fail, the timing belt, which has teeth, doesn’t actually slip. Instead, when the throttle is abruptly opened the tensioner can’t keep the right tension on the timing belt. The crankshaft and camshaft will come out of perfect time for a moment or two.

Look for the following signs of timing belt tensioner failure:

Acceleration Issues

Lack of perfect timing leads to acceleration issues. You may notice sluggish acceleration.

Trouble Starting The Vehicle

When there are timing belt tensioner issues, the valve timing is slightly off. This leads to hard starting It may take a while for the engine to fire up properly. Even if you manage to start the engine, expect the engine to misfire or run rough.

Strange Noises

When the timing belt isn’t tight enough, it starts making noise. Or you may hear timing belt tensioner noise. For example, the pulley may not be rotating freely. It may start squeaking as it rotates. When the engine is idling, listen for the following noises from the timing cover area:

  • Rattling noises
  • Squeaking or squealing noises
  • Knocking noises

Keep in mind that the serpentine belt also has a tensioner, and also sometimes and idler pulley. Both of these can also make the same noises as a timing belt tensioner. They are both relatively easy to inspect, and simple and inexpensive to replace. So, if you have doubts about where the noise is coming from, take steps to rule them out first. Also, if they are failing, they generally do not cause stumbling or hard starting. If they are ok, proceed to dig deeper to troubleshoot the timing belt tensioner.

We would love to hear your feedback! Contact GMB on 1300 007 132 to find your nearest stockist.