‘The timing belt? What’s that?’.
That’s a question we hear all too often. You might not think about it, and perhaps have never even heard about it, before it starts making noise. Or worse, snaps.
But this unassuming little piece of rubber (or chain) is a critical component in your engine. Without it, you’re going nowhere.
Here’s why replacing your timing belt at the recommended intervals saves you from costly repairs and unexpected breakdowns.
What does a timing belt actually do?
Here’s what the timing belt or chain actually does in a petrol-powered car with a manual gearbox.
When your engine runs, it drives pistons up and down. These connect via con rods to the crankshaft, a big, long shaft that runs along the bottom of your car’s chassis. The crankshaft spins because it’s connected to those pistons moving up and down. The crankshaft is what then connects to a flywheel, then a clutch, then a gearbox, and then the wheels. That’s what makes your car move forward.
However, your engine depends on an intricate cycle to continue working, colloquially known as ‘suck-squeeze-bang-blow’. First, a valve has to open to ‘suck’ air in to mix with fuel. Then, that air-fuel mixture has to be ‘squeezed’. Next, the spark plug ignites the compressed mixture with a ‘bang’. This drives the piston downwards again in the power stroke, making that crankshaft spin. Finally, the exhaust valve opens to ‘blow’ all the waste gases out of your exhaust pipe. This happens over and over again, thousands of times per minute in every cylinder.
The ‘suck’ and ‘blow’ parts rely on valves opening at just the right moment. But how do they know when? That’s where the timing belt comes in. It links the crankshaft to the camshaft. The camshaft has a row of raised sections called cams, or lobes. As it turns, it pushes lifters that open and close the valves at precisely the right time. Without this, the engine’s cycle would fall out of sync – and your car wouldn’t run.
Timing belt vs timing chain: what’s the difference?
Let’s address another common question: what’s the difference between a timing belt and a timing chain? Well, both of these serve the same purpose. Manufacturers choose to use one or the other.
Since the 2000s, there’s been a bit of a shift in thinking. For a while, most manufacturers used a reinforced rubber timing belt because it’s lighter, cheaper and easier to replace. The timing belt became popular in the 60s, phasing out the traditional timing chain.
However, in recent times, timing chains are experiencing a comeback. Timing chains should last as long as the engine, but we change them at regular (extended) intervals, just to be safe. Sometimes they stretch over time, but they need replacing less often than belts. Changing a timing chain is more expensive and takes longer, but because they last longer, you won’t have to worry about them as much.
These days, you’ll probably find timing belts on older VW models and those with smaller engines. Anything newer or bigger will likely have a timing chain. To be certain, check your owner’s manual.
When should you replace your timing belt?
Your service manual tells you exactly when your timing belt needs replacing. Look it up for, by far, the most accurate answer you’ll get.
Generally, most Volkswagen Group cars (including VW, Audi, Seat and Skoda) require a timing belt replacement every 60,000 to 100,000 miles. We appreciate that this might not be the specific answer you’re looking for. Unfortunately, it’s impossible to give a more accurate answer without a closer look at your particular car.
Always refer to your vehicle’s manual for the manufacturer’s specific recommendations. If you’re unsure or can’t find the information, it’s wise to consult a professional mechanic. Make sure you work with someone you trust so they don’t sell you work you don’t yet need.
However, just because your VW hasn’t yet reached the recommended service interval doesn’t mean you should ignore your timing belt.
Signs your timing belt needs attention
A worn or failing timing belt can lead to severe engine damage. Be on the lookout for these warning signs:
- Engine misfires or runs rough – if your engine is misfiring or running unevenly all the time, it could be due to a worn timing belt.
- Unusual engine noises – a problem with a timing chain or belt could sound like an unusual ticking or clicking noise from the engine while it’s running.
- Oil leaks – many things can cause oil leaks. If you notice it leaking from the front of the engine, it could be a worn timing belt seal.
- Check engine light – these always come on for a reason. It could mean almost anything, including a faulty timing belt.
If you notice any of these symptoms, have your vehicle inspected by a professional mechanic as soon as possible.
Your technician will check that everything’s working as it should during a regular service. But they won’t take the engine apart just to look at the timing belt – it’s hidden deep inside, and if there’s no sign of a problem, there’s no need to go digging.
Your service schedule might say the timing belt doesn’t need replacing until 100,000 miles. So what happens if you notice issues at 90,000 miles? Well, don’t ignore it. Go straight to your service centre and have them take a closer look. It’s much cheaper to fix the timing belt on your own terms than wait for it to snap.
The consequences of a timing belt failure
The thing is, just waiting for your timing belt to snap could have pretty severe consequences.
On the surface level, any breakdown is inconvenient. And expensive. You’ll need to get your car towed to a garage and, if you need it back urgently, may have to pay extra to get the part delivered and fitted quickly. In the meantime, you’re potentially losing working hours and creating a backlog of things to do with your day.
When the timing belt snaps and flies off, the belt itself is unlikely to do much damage (even though it’s spinning very quickly under tension). That said, sometimes bits of rubber clog up inside pulley gears or covers, so sometimes need cleaning from the surrounding mechanical systems before fitting a new timing belt.
That doesn’t apply if you have a timing chain, though. If the chain snaps and comes off, it’ll shred through your engine and could do a significant amount of additional damage under the bonnet.
And then there’s the big one. Interference.
In interference engines, pistons and valves move in the same space inside the engine, but never at the same time. The timing belt keeps them working together without crashing.
If the timing belt breaks, the valves can hit the pistons. That causes serious damage. You may need to replace not only the belt but also the valves and cam cover or even rebuild the entire engine.
Many Volkswagen Group engines are interference types, like diesel TDIs and petrol 16-valve TSI, VR6 and 2.0T models. That’s why it’s vital to replace the timing belt on time and fix any warning signs straight away.
How Sunset VW can help
At Sunset VW in Derby, we specialise in servicing and repairing Volkswagen Group vehicles, including VW, Audi, Skoda and SEAT. Our experienced technicians are here to inspect your timing belt and replace it if necessary. And if something does go wrong out there, we’re fully equipped to get you back on the road as quickly and cost-effectively as possible.
If you’re unsure about your timing belt’s condition or replacement schedule, don’t hesitate to contact us. As Derby’s family-friendly Volkswagen garage, we’re here to give you expert advice, welcoming service, and to keep you safely on the road.