One of the most expensive car maintenance items is the replacement of the timing belt.
This article breaks down what makes the timing belt so important and why it is vital to change it on schedule.
What is a timing belt?
A timing belt is a rubber belt that controls the timing of internal combustion engines. The belt itself is unremarkable in appearance: it is simply a rubber belt with teeth, as pictured above. However, it performs a vital function by ensuring that the crankshaft (which controls the pistons) and the camshaft (which controls the valves) rotate in sync.
This is vital for two reasons:
1) The valves need to open and close at precisely the right moment to allow the intake of air into the engine, which in turn allows the combustion of fuel and production of energy. Incorrect timing can mean limited air intake and a compromised ability to burn fuel.
2) Without the timing belt, the pistons and valves fall out of sync and collide. This is a big problem, since the valves in your engine are very fragile and bend easily. One collision with the pistons is all it takes to cause a costly repair.
When does the timing belt need to be replaced?
Unlike your brakes or suspension, there is no warning sign that your timing belt is wearing down. Your car will simply be running smoothly one moment and fail the next.
Given this, it is imperative to observe the service guidelines in your manufacturer’s logbook and always get your timing belt replaced on time. Doing so will protect your back pocket as well as your warranty. For some cars, this can mean a timing belt replacement every 60 000km or four years. For other vehicles it is every 100 000km or five years.
I have bought a used vehicle without a logbook. How do I know if the timing belt has been replaced?
The extended interval between timing belt changes mean that you may not know when your vehicle’s timing belt was changed last – if at all. The good news is that most mechanics put a sticker in the engine next to the belt that record when the belt was last replaced.
Be aware that an aging timing belt isn’t usually picked up in a safety certificate inspection, since that certificate is purely to indicate that the car is roadworthy at the time of sale or registration. Before buying a used vehicle, it is a good idea to ask a mechanic to check the timing belt during a pre purchase inspection for signs of wear. Otherwise, you may find yourself copping a major service bill soon after purchase!
Why is a timing belt replacement so expensive?
The timing belt itself is a relatively cheap part to buy. The reason why the replacement is usually costly comes down to the location of the timing belt in your engine. To access the timing belt, your mechanic will generally need to dismantle and reassemble your engine bay – easily a few hours of work.
Although there are multiple guides online that step you through the replacement process, this is definitely a job for the professionals. One wrong move in sync rosing the shafts or incorrectly tuning the engine will cause the belt to fail and a big mechanic bill to fit a new belt and repair the damage done.
My mechanic has advised me that I should replace the entire timing belt kit – not just the timing belt itself. Is this correct?
The timing belt kit it made up of idlers, pulleys and tensioners which are each responsible for small but essential jobs. If these parts are worn when a new timing belt is installed, their reduced capacity to function can potentially cause your timing belt to fail in a very short time, without warning.
It is for this reason that many manufacturers require the replacement of the entire timing belt kit as part of their logbook servicing – not just the belt itself.
In addition to this practical consideration, the labour time involved in accessing the timing belt means that it makes good financial sense to replace the entire kit in one go. Otherwise you may find yourself doubling up on labour costs down the track!
Need to book a timing belt replacement for your vehicle?
