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What’s A Cam Belt & Why Is It Failing?

Collision damage from crashes aside, one of the most common reasons people use our service is down to engine damage caused by failure of the cambelt or timing chain. It usually means that a car requires a new engine, or at least a top-end engine rebuild and in most cases the cost to do that is more than the value of the car itself which is why many choose to sell it for scrap or salvage.

Multiethnic couple standing near breakdown car during road trip

What Is A Cambelt And What Does It Do?

The cambelt in your car is a lot more important that its rudimentary appearance gives away. While it is a fairly simple component when laid out on a garage workbench, its job is to keep the intricate parts of your vehicle’s engine moving in sync with one another so that they don’t end up smashing into each other inside your engine.

The engines in most cars are four stroke engines, and this is how they work:

  • As the pistons go up and down they suck in air and fuel and compress that mixture which ignites, causing an explosion to shove the piston back down.
  • On it’s way back up again it forces the burnt mixture out again – which, in short, means: Suck, Squeeze, Bang, Blow which you can see in action in the animation below. Although in real-life it operates much, much faster!
Engine operation animation

Image credit: Zephyris, CC BY-SA 3.0, Link

With so many parts of metal moving at such speeds, it’s vital that the valves at the top of the engine don’t come into contact with the pistons – which is why timing is crucial. The belt with the arrow on the left hand side of the above animation represents the cambelt, or timing chain. Its job is to make sure that when the piston is heading rapidly upwards the valves remain closed or are only open just enough that the piston doesn’t touch them and so when a cambelt or timing chain fails, this finely tuned system gets out of sync, or out of line which means that the moving parts within your engine are free to collide, causing catastrophic and usually terminal damage.

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How To Prevent A Cambelt Failure

Regular scheduled maintenance is key. When manufacturers design and test engines they attribute a lifespan to different components with a decent safety margin built in. If you look in the service handbook of your car it will tell you when the timing chain or cambelt should be renewed. This is generally related to mileage, but also time. Timing chains are made from metal but cambelts are typically made using rubber and so it perishes with both time, and use, which means that even if your car doesn’t do many miles the cam belt will eventually wear out.

Are Cambelts Expensive To Replace?

The cambelt itself is not particularly pricey – at least not when you look at the cost of motoring on the whole. However, the job can be very labour-intensive, so don’t be surprised if there’s a rather large fee on your invoice on top of the price you’re paying for the component. Many people wonder when to change their cam belt – often, the price forces them to do so as little as possible.

Why Do Garages Keep Quoting For Changing The Water Pump As Well?

The timing belt or chain on your engine doesn’t only control the opening and closing of the valves but they also drive the pump which moves water around the engine to prevent it from overheating. Like the belt, the pump has a limited life and since neither component is particularly expensive to replace, it is often best practice to change both at the same time to save on labour costs. Plus, the few hundred pounds to do this job now, is far better value than a few thousand for a new engine or car!

What’s The Difference Between A Cambelt & A Timing Chain?

The difference between these two components is subtle, but very obvious to those with any knowledge of how cars work. A cambelt is simply a belt. It looks similar to the kind you’d wear around your waist, except this kind is wrapped around your vehicle’s engine and revolves in the blink of an eye.

A timing chain, on the other hand, is just that – a chain. Rather than using a belt that’s malleable and susceptible to wear and tear, timing chains are sturdier. They’re also situated inside the engine, unlike belts, where the former is lubricated using your vehicle’s oil.

All in all, their jobs are essentially the same.

What Are The Signs Of A Cambelt Failure?

Car Won’t Start

If you car won’t start, it could unfortunately be down to a cambelt failure. If your belt has worn down to the point of failing, or worse, snapped altogether, then your vehicle won’t be able to get the camshaft moving.

Visible Smoke

Smoke pluming from your car is an issue that has happened to enough people that we all immediately know that something is seriously wrong. A dodgy cambelt can cause this as your engine is unable to burn fuel in the correct way.

Unusual Noises

Like smoke, uncomfortable noises are often a dead giveaway that something is up with your car or van that needs fixing, and fast. If it’s your cambelt, you can often hear a horrible squealing sound that’s sure to unsettle yourself and everyone else within earshot.

No Power

The engine could misfire if your cambelt is damaged, which in turn can result in numerous power-related problems and even a decrease in fuel efficiency.

A man stands in front of his broken down car which has the bonnet raised

Reasons For Cambelt Failure

As with any part of a car, there are a lot of things that can go wrong with your cambelt and cause problems. These include:

  • Overtightening of the belt can cause it to stretch
  • Excessively hot or cold temperatures
  • General wear & tear over time
  • Misalignment, either from poor installation or inference from debris.

What Do I Do If A Cambelt Or Timing Chain Fails Prematurely?

There isn’t much you can do to prevent this, minus changing them regularly, but that’s an incredibly uneconomic way to solve a problem which may not even occur. However, there are steps you can take to avoid being out of pocket.

  • Check If It’s Covered – It’s tempting in this kind of situation to go to an independent garage for a cheaper fix, but that’s not always the case. Even if your car is out of warranty, if it is still relatively new and you are confident that it has been serviced and maintained as scheduled make sure you return the vehicle to a main dealer as manufacturers don’t like bad publicity, and it could be something which the manufacturer will authorise the dealership to fix at their expense. This is usually the case if it is an obvious issue or you can demonstrate that it’s premature component failure. Plus there’s always the chance that if they won’t cover the full cost of the repair, they may offer a financial contribution as a gesture of goodwill in effort to retain you as a customer.
  • Be More Careful Next Time – Get the belt replaced, but next time, look and listen out for the telltale signs that something’s not right, and make sure you keep on top of that important maintenance!

If your dealership won’t play nice, or you can’t afford the repair fees you’ve been quoted, you may be better off selling your car as scrap or salvage with us here at Scrap Car Comparison. Get a quote today and we’ll put you in touch with Authorised Treatment Facilities (ATFs) that are eager to purchase your vehicle from you. They’ll even collect your car or van for free!

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