Cambelt change, repair & replacement made easy

What does a timing belt (cambelt) do?

The timing belt (or cambelt) is a toothed, strengthened rubber belt used to rotate the camshafts at the correct time with the pistons, hence “timing belt”.

How does the timing belt (cambelt) work and what are the components?

The timing belt has a specific number of teeth that are matched in perfect harmony with the cog on the crankshaft and the cogs on the camshaft(s). This is set to rotate the camshaft so the valves open at the precise time they are meant to in correlation with the rise and fall of the engine's pistons.

The timing belt is usually held in place by a tensioner and a guide roller.

On many engines, the water pump is driven by the belt as well. If this is the case, it is imperative to have it replaced at the same time. There are two reasons for this, firstly, the water pump is a pulley and bearing that forms part of the circuit the belt travels around and should it fail, then the belt will come off and that is the same as it breaking. Also, water pumps are prone to seizing, which again will break the belt.
The second reason is that should the water pump fail (and not damage the belt etc) and require replacing, then the timing belt would have to be renewed at the same time, so its best to have a new one fitted as a preventative course of maintenance.
Most mechanics will not carry out the work unless the pump is replaced in the situation as they know the consequences!

Under no circumstance should a timing belt be put back on once it has been removed, no matter how recently it was done. Any small nicks or damage to the belt during the process could be catastrophic - so no, for the cost of the belt itself its not a risk that any mechanic would take

The timing belt is hidden from view and protected by a cover in the vast majority of cases.

How do you know there is something wrong with the timing belt (cambelt)?

Sadly in 99% of cases you will only know if there is an issue with the cambelt when it breaks! This can occur at any time, at any speed and usually at the most inconvenient time and place. This is why manufacturers give recommended replacement intervals, both in terms of age and mileage. It is preventative maintenance that should never be overlooked.

How common is a timing belt (cambelt) replacement?

Every vehicle which has an engine that uses a timing belt, needs to have this done as part of the scheduled maintenance, so it's an everyday occurance for mechanics.

Whilst a cambelt is made of strengthened rubber its life span is generally between 5-8 years depending on the manufacturer. If you consider it like an elastic band, an old one is more likely to break when you use it than a new one due to it perishing over time.

If the cambelt should break, then the pistons will continue to rotate momentarily and collide with the valves in the cylinder head as they are no longer in the correct position as the camshaft will have stopped turning. The result of this collision can result in severe damage to the engine, from bent valves, to broken engine internals. It can even destroy an engine completely. Unfortunately there are very few engines where you will get away with it breaking and just require a new belt although a few manufacturers have intentionally engineered weak points in the rocker arms to reduce the damage should it occur.

If your car is fitted with a timing belt (and not a chain), then the replacement needs to be carried out at the time stipulated by the manufacturer. This could be between 5 - 7 years or 60,000 to 100,000 miles. So in reality, it is a very common jobs as all cars equipped as such need to have this done.

If your car is around this age, and you have no record of the job ever having been done, it would be wise to get the belt replaced rather than chancing it. You cannot generally check to see if a belt has been replaced recently or not as not only is access difficult, what you can see doesn’t give clear indication of its age.

How can I extend the life of my timing belt (cambelt)?

Sadly, there is nothing you can do, just make sure you do not go beyond the recommended change schedule.

What happens during a timing belt (cambelt) replacement?

• Mechanic will remove or loosen the components required to gain access to the cover. This may also involve removing a wheel as well, so do not be alarmed!
• Mechanic will then lock the camshafts and crankshaft in place with timing pins, before removing the old belt and associated guides and tensioner.
• Mechanic will also drain the cooling system and remove the water pump if it is driven by the belt
• Once a cleanup has been done, the mechanic will renew the components and finally fit the new belt.
• Any components removed will be put back in place, the cooling system replenished and the engine started and tested.
• The cooling system will then be bled of air and the vehicle road tested.

How much does a timing belt (cambelt) replacement cost?

The cost of a timing belt replacement depends on your car and what parts your car's manufacturer recommends using for the replacement. Find out what you could save by having your timing belt replaced by ClickMechanic, by selecting your car at the top of this page!