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Sep 2, 2019
Timing Belt: What is it and how often should it be changed?

You’ll have heard of timing belts and timing chains being a part of your car’s engine, but what does timing mean? Has your car got a belt or a chain? What are the possible problems with a belt?

What is a timing belt?

We are focusing on the timing belt in this feature. In brief, timing is how the valves (inlet and exhaust) open on your engine in precise accordance with the movement of the pistons – this is all a matter of very precise timing, you see, and hence the phrase ‘timing belt’ for the item which controls this combustion ballet. The belt is attached to a series of sprockets and pulleys in your engine, which determines exactly when the valves open to optimise your engine’s performance through the most efficient burning of the air/fuel mixture. Some diesel engines also have fuel pumps that are driven and ‘timed’ by the same belt.

Over time, a belt will wear. It may show signs of cracking, it may stretch and cause the engine to lose power or run poorly, or it may snap altogether. In the last instance, this could be disastrous for your car; if the timing belt snaps and the timing goes off while the engine is running, then valves could hit pistons and be bent/damaged beyond all repair. In this instance, you will need a very, very expensive top-end repair job to be done to make your engine work again, so it’s best to replace the belt before or at its scheduled maintenance point.

Oh, and belt versus chain? The belt is obviously cheaper, in terms of both its component cost and replacement charges, but chains tend to be a bit stronger and longer lasting. However, even chains can wear out and snap, so it’s not a fool proof mechanism for engine timing.

Will my car have a belt or a chain?

This is a huge question and one we simply don’t have the space here to answer in full – the best way of solving this would be to list every car that has a belt, and every car that has a chain. However, there are plenty of good online resources that will list cars with belts and cars with chains, which will come up with a simple ‘does my car have a timing belt or timing chain’ Google search (other internet search engines are available). If you can see a plastic cover affixed to the side of your engine, then you most likely have got a belt; if not, it’s probably a chain. However, the advent of full-engine plastic covers that sit on top of the whole unit tend to make this sort of identification hit and miss.

How often should I replace my belt and how much will it cost?

Typically, belts last between 100,000- and 160,000km before needing to be replaced (it varies considerably from engine to engine so don’t take this as an absolute guideline – always check what it should be for your car). They’re not the simplest jobs to do and, unless you’re mechanically savvy and know what ‘top dead centre’ means, it’s best to take your car into a garage to have the work done. It will typically cost you a few hundred Euro to have a belt replaced, but while that’s hardly inexpensive, it’s as nothing to the cost of repairs if you fail to have the belt replaced and it snaps further down the line.

What are the symptoms of a wearing timing belt?

The most obvious signs of a belt on its last legs are a loss of power when accelerating, slippage (normally identified by a high-pitched, intermittent screeching sound from the engine), slow pick-up at lower revs and even a rattling noise from the engine (although this is more commonly associated with worn, stretched timing chains). Get it seen to as soon as possible.

Author: Carzone

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