Your cambelt (or timing belt) is a vital part of your engine. It is responsible for keeping some of the critical moving parts such as the camshaft, crankshaft and pistons, operating in sequence. If the timing belt fails, there is a potential for severe damage to your engine, which is why manufacturers recommend that it is replaced at a certain mileage. Luckily the AutoMend network is on hand to put you in touch with your local vehicle maintenance and repair experts. We’ve got the UK covered, so there will always be someone available locally whether you live in England, or in Scotland, Wales or Ireland. Whether you are looking for a routine cambelt replacement, or in need of a repair following a timing belt failure, our members can help.
A break in a timing belt most often happens when starting up or switching off your engine. The reason is that these are the two phases of engine use when the tension on the belt is at its highest.
For a non-interference engine, this does not usually cause any real damage. The end result will usually be a requirement for a cambelt or timing belt change by a competent mechanic.
For an interference engine, there will almost certainly be damage caused. A belt breaking at start-up or shutdown, may cause bent valve stems or damaged valve guides. A belt breaking while the car is running at speed can cause a great deal of damage. The valves may break away into the cylinders, bending connecting rods and destroying the piston. Further damage to the cylinder head and the engine block is also possible – you may end up needing a replacement engine.
Belt tension is critical. A badly adjusted belt can slip or whip if it is too loose. If it is too tight, it can put excessive strain on the bearings of the cogs it connects with. This can strip teeth, cause excessive wear a shortening of the belt life, and can make the engine noisier. The belt is held at the correct tension by tensioners, which themselves can fail, allowing a derailment of the belt.
The material that a typical timing belt is made from contains polyester, fibreglass, Kevlar cables and steel wire. A belt can fray with use, and small pieces of the material can run around inside the engine compartment, risking damage to other components. Additionally, even if your vehicle does not do many miles per year, you still need your timing belt replacing because corrosion can be going on undetected.
If you have a timing chain, and it is loose, you may hear a rattling noise coming from the front of the engine. This can be an indicator that it may need tightening or changing.
A broken chain at low speed may not cause any real damage. However, a break at high speed and therefore high RPM is a different matter. The metal chain will basically whip around your engine and cause damage wherever it lands. The result can be very expensive indeed, you may end up with a written-off engine.
The majority of petrol or diesel car engines are what is known as ‘four-stroke combustion’ engines. The name ‘combustion’ is used because when the engine is operating, it burns the fuel. The ‘four-stroke’ part of the name is because the process of burning the fuel in the engine is accomplished in four strokes. These are: intake, compression, power and exhaust strokes. During one cycle of the four-stroke process, the camshaft rotates one whole turn, and the crankshaft rotates two whole turns. The turns of the camshaft and the crankshaft operate the valves and pistons inside the engine’s cylinders, and the movements of all these parts need to be precisely co-ordinated for the engine to function. In simple terms, the cambelt or timing belt ensures that the rotation of the camshaft and the crankshaft in your engine operate in time with each other. This timing, known as synchronisation, ensures that the engine valves open and close at the appropriate time as the pistons in the cylinders perform their intake and exhaust strokes. If your car has what is called an ‘interference engine’ the cambelt has another critical task. This is to make sure the pistons, which share the same operating space as the valves, do not come into contact and collide.
This is a type of engine where the valves, when fully open, extend into the space within the cylinder that the pistons also use. They don’t do this at the same time – the timing belt is there to prevent them coming into contact. This type of engine is highly efficient, but maintenance is critical to prevent issues such as a broken or slack timing belt. If the belt isn’t operating properly, a collision within a cylinder can damage your engine beyond repair.
It can be confusing when there are several names for what appears to be the same thing, so let’s look at the similarities and differences between a cambelt, a timing belt and a timing chain.
A cambelt and a timing belt are both toothed belts. They have teeth on the inner surface, and are usually made of a composite material, similar to that used in tyre manufacture. A timing chain is just that – a roller chain, similar to a bike chain, and is made of metal. Belts are lighter, cheaper, and tend to run more quietly than chains, because they are made of softer material. However, chains do not wear out as quickly as belts.
In very simple terms, a timing belt and a timing chain do exactly the same job but are made of different materials. The cambelt, does a similar job to the timing belt, but operates in a slightly different way.
The cambelt or timing belt is a wear component. It is not expected to last for the life of the engine and will need replacing at some point. Most motor manufacturers estimate timing belt life to be around 60,000 to 120,000 miles. You will find the exact figure for your vehicle in the manufacturer’s handbook. If you plan to embark on a long car journey, as part of your preparations check that timing belt replacement will not fall within the planned mileage. Get the belt replaced before you go, and it will be one less thing to worry about.
When you have your timing belt or cambelt changed, the belt tensioners (which wear at a similar rate) will also be changed as a preventative measure.
It is best practice for a water pump to be replaced at the same time as a cambelt or timing belt. This is recommended for several reasons. Water pumps are wear components that are expected to be replaced during the life of the engine. Assuming your water pump is the same age as your timing belt, it will be wearing out by the time the belt needs changing. It also makes economic sense to replace the pump at the same time as the engine is being dismantled to replace the timing belt.
If you have purchased a second-hand car, it’s a good idea to be certain if the cambelt or timing belt has been replaced to schedule. If you are lucky enough to get a full set of maintenance records with the vehicle, check back to see what was done and when. If there are no reliable maintenance records available, it can be really hard to know what has been done, and you can’t afford to continue to drive the vehicle beyond the safe age of the belt. As a precaution, book a maintenance check with your local AutoMend garage or mobile mechanic to give you total peace of mind.
When you make use of the AutoMend network, you immediately gain access to the skills and experience of more than 9,000 garages and mobile mechanics across the UK. Some of these people specialise in one or more aspects of vehicle repair, maintenance and testing, but the vast majority can handle practically any issue on any make of vehicle.
When you need your timing belt or cambelt changing, simply get yourself some quotes for the work from your local service providers. Type in your postcode / location, and you will see all the mechanics and garages in your local area, plus contact details. Pick your favourite and either contact them directly or ask for a free no-obligation online quote online.
There’s no need to do an online search and then go through page after page of results to get the best deal. AutoMend gives you instant hassle-free access to multiple industry-approved garages and mechanics all in one place. Get as many quotes as you like for your cambelt / timing belt repair, then sit back and compare the results – we are certain you will be getting the best possible value for money.