Normally when we hear someone talk about a cambelt, it is in a story linked to a lucky escape and a hefty bill. By understanding a bit more about your cambelt, what it does and how to spot signs of problems, you can save money and prevent inconvenient and potentially dangerous breakdowns.
An engine has four stages of function: intake, compression, power, and exhaust. It is essential that the intake and exhaust valves open and close at exactly the right stages to allow the air-fuel combination to enter the engine, and the exhaust gasses to leave. The crankshaft rotates as the pistons move up and down, and the camshaft controls the timing of the valves. The cambelt makes sure that the crankshaft and camshaft are in sync with each other, which allows the engine’s valves to open at the right stage of the combustion cycle.
Cambelts are made of rubber with reinforced fibres to add strength. Because rubber can perish and crack, the lifespan of a cambelt is much less than that of the engine, which is why it is important that cambelts are maintained, checked and replaced. Depending on the vehicle model, it is usually recommended that cambelts are replaced at somewhere between every 60,000 and 100,000 miles. If you are uncertain, check with your manufacturer or ask your local garage for advice.
If a cambelt breaks, the impact on the engine can be very serious, especially in engines where pistons and valves are in the same space as the engine (known as “interference” engines). In the worst case, a cambelt snapping can cause open valves and pistons to collide, bending the valves, damaging pistons with the potential to damage the engine beyond repair.
Cambelts don’t usually just snap without warning – there are usually signs which, if spotted in time, can prevent catastrophe. If your engine starts making unusual noises, particularly ticking or whining sounds, if you have difficulty starting the engine, or you notice your engine misfiring, it may be worth investigating further. A visual check may highlight the culprit; it may be easy to see cracks, fraying, or other signs of wear. However, one of the main problems with cambelts is that they can be notoriously hard to get to, so you may need to ask your mechanic to check it out.
It is important to remember that not all vehicles have cambelts; some have timing chains or wet chains. These chains work in a similar way to cambelts but they are made of metal, which means that they are more durable so likely to need changing less often, if at all. Timing chains can, however, stretch over time, so regular maintenance is still needed even if they won’t necessarily need changing.
If you are concerned about your cambelt or you have started to notice mysterious noises from your engine, take your vehicle to a trusted local garage to get it checked, before disaster strikes. For more advice, follow Trust A Garage on Facebook or X.