Today, we’re going to answer a few questions that regularly come up when discussing the performance of a timing chain. A timing chain is a hard-working yet sturdy component of your engine’s performance, ensuring that the pistons and valves open and close in perfect synchronisation and a range of other essential actions.

What is a timing chain?

A timing chain controls the pistons and valves in your engine cylinders, making sure they fire at precisely the right time without crashing into each other. For a full rundown of how your timing chain works, check out our article, What does a timing chain do?

All manufacturers fitted timing chains in their cars back in the good old days, yet with the introduction of new materials, most were replaced with rubber timing belts in the 60s and 70s. The new rubber options were easy to manufacture, much quieter, and easier to access and replace. However, timing chains made a partial comeback in the 90s, in specific models and marques, due to their advantages, and are once again a vital car part in the motor industry.

When should the timing chain be replaced?

Despite the suggested mileage for each marque’s timing chain replacement, most chains are expected to last the life of the vehicle. Therefore, the ‘recommendation’ for their change generally considers the expected wear and tear over those miles and the effect it can take on those chains.

At its serviceable mileage

The general rule of thumb is somewhere between 80–120,000 miles, but as you know, it’s essential to check what each manufacturer recommends in your vehicle handbook. With such a vast difference in possible ranges, it’s vital you know which is correct for your car.

When it’s wearing out, damaged, or dying

Chains stretch over time; it’s just how it is. So, if a chain elongates, even slightly, that little bit of additional slack can deliver a few tell-tale signs that it might finally be time to replace it.

If it snaps

It’s not a common problem, by any stretch, but if associated parts fail, it can lead to a timing chain snapping completely. As you can imagine, it’s a pretty serious problem, as the knock-on effect it can have on your engine can be disastrous and even fatal.

Symptoms of a failing timing chain

Engine misfires and starting problems

If the chain isn’t operating at the correct tension, there’ll be a knock-on effect on the engine performance. This can manifest in misfires, problems starting the car, its performance could feel sluggish or run low on power.

Rattling sounds

A worn chain or tensioner and a loose timing chain can cause noises from rattling and whirring to clunks and whines.

Some noises and poor performance issues will lessen as the engine warms up. This is because warming the car and engine gives the oil a chance to hit its correct working temperature and the tensioner a little time to remove some of the materialised slack. Eventually, however, the chain may suffer more stretch than the tensioner can accommodate, leading to more significant, severe issues.

What causes timing chain wear?

Lack of lubrication

The timing chain operates within the engine casing, lubricated by the engine oil. If oil levels are low, there won’t be the correct level of lubrication to keep the chain at its healthiest. Likewise, using the wrong grade or low-quality oil or oil filters can have the same effect.

If you skip services here and there—failing to change the oil and oil filter—more of the dirt and debris that accumulates under regular use will build, again, working into your timing chain and preventing its optimum operation. That gunky old oil can speed up chain wear, infiltrating the chain links, causing the damage you’d expect to avoid with regular maintenance.

Failing tensioners, guides, and silencers

Your engine uses a selection of tensioners and guides to keep your timing chain operating under ideal conditions. Some are manual and some hydraulic, but either way, if they wear out or aren’t properly maintained or operated, they can have the same effect on your timing chain, causing it to stretch or suffer over time.

Should I replace the sprockets at the same time?

If you’re going to all that effort to access the timing chain, it’s an ideal opportunity to change the complete set of sprockets, chains, and associated components. A worn or stretched chain will often impact the rest of the system, where a snug fit and precise operation are paramount.

As well as the sockets, other parts would also benef