Bad Timing Chain Tensioner – Symptoms, Causes & Replacement Cost

The timing chain tensioner’s primary role is to maintain the appropriate tension on the timing chain while ensuring that the crankshaft and camshaft rotation are in sync.

Often, the tensioner may get damaged and fail due to many factors. These factors may include damaged springs, leaking oil, engine overheating, wear and tear, etc. When this happens, it comes with some obvious signs.

You may notice a change in the engine performance when the tensioner is damaged. Other signs include bad timing chain tensioner sound, engine light, oil leaks, etc.

Once you notice these symptoms, please do not ignore them, as it can develop into a more serious issue. If the tensioner problem is not checked and fixed, it could lead to engine failure, which will cost even more to fix.

What is a Timing Chain Tensioner, and how it works?

The timing chain tensioner is an engine component that controls or regulates the tension on the timing chain. If the pressure on the timing chain is inaccurate, the movement between the crankshaft and the camshaft will not be synchronized.

What is a timing chain? The timing chain is made out of metal, which links to each other to connect two components. In this case, the two components are the crankshaft and camshaft.

Furthermore, the crankshaft is an essential part of the internal combustion system. It converts the vertical motion of the piston into a rotational one, which will be used to power or drive the vehicle’s wheels to create movement.

On the other hand, the camshaft also uses rotational movement from the engine to open and close the valves. In this case, the valves are the intake and exhaust valves.

The crankshaft and camshaft in the engine must rotate in synchrony. It ensures that the valves open and close in an accurate sequence.

The timing chain ensures that the crankshaft and camshaft movement are synchrony. The timing chain is connected to the end of the camshaft and then links to the crankshaft. By this connection, the chain can transmit the movement of the crankshaft to the camshaft.

For the timing chain to properly transfer crankshaft movement to the camshaft, it needs the right tension. It is when the tensioner comes into play. The tensioner uses spring or oil pressure to ensure the chain is tight. As long as the chain maintains its tightness or tension through the help of the tensioner, it can keep the camshaft and camshaft synchronized and moving smoothly.

What are the Symptoms of a bad timing chain tensioner?

When the bad timing chain tensioner gets damaged, the chain becomes loose when the vehicle experiences loose timing chain symptoms.

Below are some of the common symptoms of a bad timing chain tensioner.

1. Engine misfire

When the timing chain tensioner is bad, it will be unable to keep the chain tight, which could cause the engine to misfire. It could happen when the chain does not properly transmit rotational power from the crankshaft to the camshaft.

Once the timing chain is bad, the camshaft and its components will be affected. The valve timing will not sync, and the spark plug will fire incorrectly, resulting in engine misfire.

2. Reduced engine performance:

A bad-timing chain tensioner will cause a drop in the engine performance once the tension in the chain is lost. Once this happens, the valve timing will become inaccurate, which could cause some engine faults, including misfiring.

Also, when the chain has lost tension, it could skip teeth or lead to improper synchronization. As a result, the pistons could collide, causing serious damage.

As all these happen, the engine cannot fire on time and cause premature combustion. It will lead to a drop in the power output of the engine.

3. Rattling or knocking noise:

A bad-timing chain tensioner will cause a rattling or knocking noise in the engine. It is because this is because the tensioner has failed to create tension on the chain. The loose chain moves freely, causing it to whip on parts of the engine as it tries to rotate.

4. Difficulty in starting the engine:

A bad-timing chain tensioner will also cause the engine to start hard because the valve timing will be off. The valve time is important for the process of internal combustion. It controls the flow of the mixture of air-fuel going into the engine and exhaust gasses that go out of the engine.

When the valve timing is incorrect due to the bad tensioner, the valve can be stuck on open or closed. If it is closed, then there is no way fuel could get to the combustion system. In this case, the engine will not start.

5. Oil leaks:

Most vehicles use a hydraulic timing belt tensioner. It means that the device uses oil pressure to maintain an accurate tension on the chain. The oil pump inside the engine supplies the tensioner with witty boil pressure.

Once the tensioner is damaged, it creates an opening for oil to leak to the ground. Once you notice oil leaking from the tensioner, you need to have the device changed immediately. 

6. Uneven timing chain wear

Also, once the tensioner is damaged, the chain will slack as it loses tension. When this happens, the chain will keep jacking upon startup, which will increase the wear and tear of the chain. This could further just on more than one tooth, which could cause it to break, causing the camshaft to be completely off and engine performance to decline.

What Causes Timing Chain Tensioner Failure Earlier?

Many factors could cause the timing chain tensioner to fail, including the following.

Engine overheating:

When the engine becomes overheated, the metal components of the timing chain tensioner will begin to expand, causing it to fail instantly. Also, during engine overheating, the timing chain is affected as the metal parts of the chain will also expand, causing it to become too loose and misaligned.

In most cases, engine overheating is caused by issues with the cooling system or low engine oil. You must check these components periodically to avoid problems with the timing chain and tensioner.

Wear and tear:

The timing chain tensioner is also prone to wear and tear, which could damage the device earlier than expected. Many factors could cause the tensioner to wear faster, including the following.

Loss of spring compression

The spring compression ensures the chain is always in the right position, preventing it from slipping. Once the spring is worn out and does not hold compression, the chain can jump off position, causing issues with the tensioner and other engine system parts.

Oil leaks:

Yes, oil leaking is both symptom and cause. Once there is an oil leak in the oil line or pump, it could affect the timing chain tensioner. In some cases, the leaks are not significant and may not affect the condition of the tensioner as long as the right oil pressure gets to the device. However, if the leak is left unattended, it becomes more significant, which could then affect the tensioner.

An oil leak would cause the tensioner to lose oil pressure, not allowing the device to give the timing chain the right pressure. It will cause the chain to get loose, causing engine issues.

But you must not confuse oil leak from the drain plug with that of the oil line. They differ in causes and aftermaths.

Wrong oil type

The timing chain tensioner requires oil pressure, but people do not know that not all types of oil work for the tensioner and the engine in general. This is why the vehicle manufacturer recommends a specific engine oil type.

Using the wrong engine oil will damage major parts of the engine, including the timing chain and the tensioner. 

Extreme mileage

The more you use your vehicle, the faster engine components will wear. The same thing happens to both the timing chain and the tensioner. How you use your vehicle will determine how long these parts will last.

If you are a regular driver and carry out extreme work with your vehicle, you need to have a good maintenance strategy for your vehicle’s engine.

How to Replace Bad Timing Chain Tensioner

If you notice the signs of a bad timing chain tensioner, and you can confirm that the tensioner is damaged, then there is a need for a replacement.

Below is how to check the timing chain tensioner and make appropriate fixes.

What happens if you don’t change the bad-timing chain tensioner?

A bad-timing chain tensioner will cause the change to lose tension, which could lead to all sorts of engine issues. If the problem is fixed without checking for the said issues, the combined engine issues will lead to engine failure, which may require a part-full engine replacement, which will cost more.

When the tensioner is damaged, the timing chain is the first component that would be affected. The timing chain requires a good measure of tension to transfer the rotational movement from the crankshaft to the camshaft and synchronize their rotation. 

Once the timing chain is affected, the camshaft and crankshaft will no longer be synchronized, leading to several issues. Some problems may include engine misfiring, loss of engine power, engine oil leaks, and more.

If the issue remains unchecked, the engine will eventually stop functioning. It means you will no longer be able to drive the vehicle.

How much does it cost to replace the timing chain tensioner?

The average cost of replacing a timing chain tensioner is $300 to $1500, including labor. The cost of replacing the tension depends on what type of vehicle you drive and the mechanic handling the replacement. Luxury vehicles like Mercedes, BMW, and more will cost more to replace. This is because their parts cost more, and specialized labor for these vehicles charges more.

According to repairpal.com, you can find a chart displaying the timing chain tensioner cost of different brands and models of cars.

How Often Should I Replace My Timing Chain Tensioner?

The timing chain tensioner is expected to last between 80,000 and 120,000 miles. However, there is no recommended time frame to change the tensioner. The device is expected to run long and should be checked regularly.

Although the tensioner is expected to work for a long time, there are instances that it gets damaged or fails prematurely. When the tensioner is poorly maintained, it is expected to wear faster.

Also, the condition the tensioner is used in would determine how long it will last. If you are a regular driver and use the tensioner under extreme driving conditions, it might not last as long as you would expect.

You are expected to check the timing chain tensioner anytime the vehicle is taken for servicing.

Important Tips to Avoid Early Timing Chain Tensioner Failure

Below are important tips for a long-lasting timing chain tensioner.

Final words

When you notice the symptoms of a bad timing chain tensioner, it is important that before changing the tensioner, you figure out what could be the cause of the damaged part. Doing this can prevent the same damage from occurring again due to the same cause. Also, having a professional handle the diagnosis and the vehicle would be better. It ensures that there is no further damage done to the car caused by the bad timing chain tensioner.