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All about the timing belt

nicad 29/07/2021 654

All about the timing belt

SummaryWhat is timing? What is the timing belt for? Timing belt and timing chain: what's the difference? Why change your timing belt? When to change it? Changing a belt, how much does it cost? Can we change it ourselves?

What is the distribution?

An engine is a mechanism that is both fine and powerful. Fine because all the cogs must fit together correctly (sometimes to the nearest millimeter) and powerful because the physical forces at play inside an engine are extremely violent: the pressure and temperature are extremely high.

To put it simply, here are the elements involved in the operation of a distribution:

The camshaft: it is the organ which manages the opening of the valves The valves: these are the elements that manage the injection of air and fuel into the pistons The pistons: these are the elements that allow both the fuel and the air to burn in the engine (therefore what keeps the car moving) , as well as the exhaust, that is to say the gas outlet. The piston is inserted into the cylinder. The crankshaft: it is the shaft which coordinates the pistons.

The following video shows how the engine works with the different organs mentioned:

What is the timing belt?

For an engine to work, all the mechanical elements presented above must be properly coordinated! Otherwise, a piston will, for example, strike against a valve, and break it! The "distri", which includes the timing belt, allows the coordination of these elements continuously, as follows:

The timing belt takes its rotational force from the engine block: when the engine is running , the crankshaft turns. A pinion is installed at the crankshaft, at the output of the engine block, which will allow the belt to be driven.

The rotation of the belt will therefore drive other pinions (also called toothed wheels) which will drive the camshafts (which drive the valves).

It is this transfer of mechanical energy that makes it possible to distribute energy and coordinate the moving parts of the engine continuously, hence the name of the "timing" belt.

The belt distributes both of energy to other components, such as the fuel injection pump, water pump and camshafts (and sometimes the accessory belt), and it allows the proper combustion and functioning of the moving parts to the inside the engine block. It is therefore an essential element in the operation of an engine.

Timing belt and timing chain: what's the difference?

Some manufacturers choose to replace some of their engines with the toothed rubber belt by a timing chain. Basically nothing changes, the timing function is just as well provided by a chain.

That said, chains are much more robust, and rightly so: metal is less subject to wear and tear. than rubber! However, watch the hydraulic chain tensioners on some models. A tensioner problem is manifested by a metallic noise. In this case, it is better to call your mechanic before it is too late!

Below you can see two examples of distribution systems:


Example of a distribution chain

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Why change your timing belt? < / h2>

The belt is mostly rubber, but it is very strong. Its wear is very slow so it should only be changed infrequently. However, it is a component that wears out over time and as it rolls over. At any given time, there may therefore be a risk of wear and breakage! Manufacturers therefore recommend replacing it as a preventive measure, depending on the age and mileage of the car.

When to change it?

Changing a timing belt Usually occurs every 5 to 7 years after the car has been put into service, or every 80,000 km to 150,000 km. Each manufacturer will have different change intervals, so the intervals can vary greatly.

Check with the manufacturer of your car or the one you want to know its recommendations. You may also be able to find information in your maintenance log or in a technical magazine. At CapCar, thanks to our inspection report, you will know for each used car presented on our site what to expect and when.

If your car has not been driven for a long time or that you want to buy a car that has been idle for a while, be careful: the rubber of the belt can dry out, thereby increasing the risk of breakage. It is therefore necessary to change the timing belt as soon as possible.

Changing a belt, how much does it cost?

The price of parts is moderate because a single belt is worth around 80 € and a complete kit including the tensioner roller and the water pump will be around € 220 (at Oscaro or Mister Auto for example). On the other hand, it is the cost of labor that is high when changing the timing belt, because it takes time: from 3 hours to 6 hours on average. The labor hour is around 60 to 80 € per hour depending on the garages and brands (Feuvert, Midas, Norauto, Manufacturer's network, local garage, etc.).

This cost and this duration are justified by the fact that the belt is a part which is not very accessible and which requires dismantling several elements before being able to access it. So it's not so much the parts that are going to be expensive, but the intervention itself. The cost of a replacement is therefore generally between 500 and 800 €, and will depend on your car (cheaper on simple and widespread cars such as city cars, more expensive on a sedan or an SUV).

When you replace the timing belt, you will almost always change the "timing kit". This kit generally includes a new belt, new timing rollers, an accessory belt, and a new water pump. Changing the water pump will drain the circuit containing the coolant. Take advantage of this type of intervention heavy enough to do a good overhaul to your car with an oil change (engine oil, oil filter, etc.)

Can you change it yourself?

If you have a good knowledge of mechanics and you have the necessary tools (setting rods and belt tensioning device), this is a perfectly feasible operation. But often, it's the lack of space and tools that is a problem! Be careful, however, if you undertake to change your belt yourself, as this is a sensitive adjustment element, and any assembly error will be fatal to the engine! Seek advice from a mechanic or from people who have already changed it themselves, or check out tutorials on the subject.

If you have little or no mechanical skills, and you you have little time to devote to the maintenance of your car, you can also choose practicality, and have your distribution kit changed at work, or at home, with an expert available for you.

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