6 Symptoms of a Faulty Timing Belt Tensioner
If you hear a squealing or whining noise under the hood when you start your engine, it could indicate a faulty timing belt tensioner. This small but important engine component keeps the timing belt tight so that the camshaft and crankshaft are properly synchronized.
In this article, we’ll explain the most common symptoms of a faulty tensioner that indicate it needs replacing, and how much it will cost to replace it.
What is a timing belt tensioner? Simply put, a timing belt tensioner is a device that maintains the proper tension on the timing belt to ensure precise synchronization of the camshaft and crankshaft. Its main functions are:
– Compensates for timing belt play and tightens the belt as components heat up and cool down. A loose belt can cause the engine to run improperly or even stall.
– Compensates for the normal wear and stretching that occurs on timing belts over time. Proper tension is important to maintain correct valve timing.
– Absorbs shocks and isolates the timing belt from other components in the system. This helps prevent belt damage and extends the life of the belt.
The timing belt tensioner works by using a spring-loaded arm or hydraulic pressure to push the timing belt against any looseness or slack. This keeps the belt at constant tension and synchronizes the opening and closing of the intake and exhaust valves with the movement of the pistons.
If the tensioner is not working properly, it can cause valve timing issues, which can be potentially damaging.
The 6 Most Common Symptoms of a Defective Timing Belt Tensioner
Here are the 5 most common signs that your timing belt tensioner is broken and needs replacing. If you notice any combination of these noises, it may be time to replace your belt tensioner.
1) Screeching noises
Creeching or chirping noises coming from the timing belt area may indicate a problem with the timing belt tensioner.
When the timing belt tensioner wears out and loses its ability to properly maintain tension on the timing belt, the belt may hit or rub against other components in the system, causing noises. This is because the tensioner can no longer compensate for its natural play and absorb the shock of the belt.
The noise of a bad tensioner may be louder or more frequent when starting the vehicle from a cold state. This is because engine components take longer to reach normal operating temperatures and expand. Colder temperatures cause greater voltage fluctuations that a worn tensioner cannot adequately compensate for.
Squeaking or whining may also occur intermittently or only at certain loads or speeds, as belt tension fluctuates more without proper damping. Removing the timing belt cover may help determine if the abnormal noise is also coming directly from the tensioner pulley area.
Squeaking or whining alone does not necessarily mean that the tensioner needs to be replaced, but it is certainly a warning sign that control system components should be checked to avoid potential engine damage, especially if other problems arise.
2) Check Engine Light
When the timing belt is loose due to a failed tensioner, the valve timing will be thrown off. This means there is a problem with the engine and the check engine light on the dashboard will be on. The check engine light alone can mean a variety of things, so you can use your car scanner to look for trouble codes and confirm the problem.
3) Knocking Noise
When the timing belt is loose, it will start to move around and hit the timing cover or internal parts. If it doesn’t sound like a knock exactly, it could be a clapping sound. Do not confuse this noise with connecting rod knock.
4) Motor does not turn
When the timing belt becomes loose due to a failed tensioner, the camshaft and crankshaft cannot be synchronized. Because of this, the mixture in the chamber cannot be ignited. You may hear the engine when you turn the key in the ignition, but you cannot turn the engine.
5) Grinding noise
If the timing belt and pulley have poor adhesion, the pulley itself will rub, rattle, and make strange noises. This is bound to happen if the pulley bearing breaks.
6) Engine misfire
Opening and closing the cylinder valves too early can cause the engine to misfire. This happens when the timing belt cannot rotate the camshaft and crankshaft at the same time.
How long does a timing belt tensioner last? Unlike the timing belt itself, tensioners do not necessarily have a manufacturer-recommended replacement interval. In most cases, the timing belt tensioner should be replaced at the same time as the timing belt, typically after 120,000 to 100,000 miles.
The tensioner’s actual lifespan is much longer than that of the timing belt, but because it’s usually difficult to access, replacing the tensioner (and water pump) as part of a timing belt replacement can save you a lot of money in the future.