- The task of a toothed belt in the engine
- When a timing belt change is due and what the change costs
- Toothed belt or timing chain?
- Tips for buying a used car
- Conclusion: No experiments with the toothed belt
The task of a toothed belt in the engine
Anyone who knows how a combustion engine works also understands the task of a toothed belt. Basically, in a car, the timing belt is that Link between the camshafts and the crankshaft.
Basics: This is how the petrol engine works
in one In a petrol engine, four processes, so-called cycles, take place one after the other. In the first stroke, one camshaft opens a valve so that fuel enters the cylinder. In the second stroke, the camshaft closes the valve again, the piston in the cylinder moves to top dead center and thus compresses the fuel. This is because the fuel is particularly effective when it is compressed.
In the subsequent third stroke, a spark from the spark plug ignites the air-fuel mixture in the cylinder. It then explodes, driving the piston to bottom dead center. Finally, in the fourth stroke, the other camshaft opens another valve through which the exhaust gases produced escape. These are the exhaust gases that the exhaust emits.
The toothed belt controls the cycles in the engine
The four strokes of the toothed belt drive ensure that the crankshaft rotates. It transfers the rotational energy to the gearbox, which finally gets the car rolling. The toothed belt ensures the general function and high efficiency at the same time. It determines the timing in the engine. Because the connection between the camshafts and the crankshaft via the belt means that the four strokes are also precisely matched to one another.
A transmission ensures that the camshafts move half as fast as the crankshaft. Accordingly, the camshaft sprockets, the so-called toothed belt pulleys, are larger than the crankshaft sprocket. In this way, the fuel and exhaust valves open and close at just the right time.
What happens in the engine if the timing belt breaks?
If the toothed belt snaps, the camshaft stops. In this state, one valve remains open and one remains closed. The crankshaft, on the other hand, continues to move. The timing provided by the toothed belt is missing and the piston hits the open valve in the second stroke. Most of the time it gets damaged. The collision is so serious that engine damage can result. In order to avoid this expensive damage to the drive, we recommend checking the belt regularly and observing the change intervals.
What is attached to the timing belt?
The main task of the toothed belt is to connect the toothed belt pulleys on the crankshaft and camshaft to one another. Additional rollers are necessary for smooth and quiet operation. Tension rollers and deflection rollers guide the belt to the toothed belt pulleys and keep it taut. In some cases, the water pump is also integrated into the toothed belt drive. This mechanically operated component circulates coolant throughout the system to keep the engine at operating temperature and not overheat.
When a timing belt change is due and what the change costs
Toothed belts are basically maintenance-free and durable. Therefore a Toothed belts are usually changed at specified change intervals, so as not to risk cracking during operation. The time intervals vary between 40,000 and 240,000 kilometers depending on the model and manufacturer of the car. The reason for the large range is, on the one hand, the engine variant, the type of belt and the vehicle model. On the other hand, the installation position or the gear ratio of the transmission influence the service life of a toothed belt.
But even if the mileage suggests a working belt, a change can be pending. Because after ten years at the latest, even a slightly stressed toothed belt becomes porous.
Where can you see if the timing belt needs to be changed?
After how many kilometers driven a change of the toothed belt is due, It’s in the car’s owner’s manual. The service booklet, in which the earlier toothed belt changes are noted, also provides information. Sometimes there is also a corresponding mark in the engine compartment. In order to avoid unexpected material failure, it is worthwhile for the workshop to carry out a visual inspection of the toothed belt during routine work.
How much does a timing belt change cost?
Since the toothed belt runs close to the engine, changing it is complicated. Depending on the engine and model, the costs are in the mid three-digit range. This is how they are put together:
- Toothed belt 40 – 200 euros
- Assembly 120 – 400 euros
- Optional: Additional components 100 -200 euros
Workshops charge around 60 euros per hour. Because of the time-consuming installation when changing the timing belt, car owners take the opportunity to also have neighboring parts replaced. Changing the water pump and the tensioning and deflection pulleys is just as useful as changing the V-belt.
Toothed belt or timing chain?
Instead of a toothed belt, some drives work with a timing chain. Manufacturers prefer these partly because they is more robust and thus withstands greater forces as the timing belt.
Thanks to its longevity, in theory it does not need to be replaced. However, this does not apply to Chain tensioners or guide rails, which, depending on the vehicle and engine, are worn out after a mileage of between 100,000 and 300,000 kilometers. In the course of this component change, workshops often also change the timing chain itself. The change package costs 200 to 800 euros plus installation.
Because the timing chain is expensive to purchase, time-consuming to assemble and somewhat louder in operation, the majority of cars have a toothed belt.
Tips for buying a used car
When buying a used car in particular, it is important that you transparently understand the condition of the toothed belt. Because unlike with a new car, you cannot simply rely on the information provided by the manufacturer. You should pay attention to these points before buying:
- Mileage and age of the vehicle: Whether the toothed belt is due to be changed is revealed above all by the mileage and the age of the vehicle. First and foremost, it is worth taking a look at the specified maintenance interval. But also talk to the seller about longer downtimes in order to estimate the condition of the timing belt.
- Evidence of timing belt changes: The change history of the toothed belt should be beyond all doubt. All toothed belt changes are usually noted in the service booklet, also known as the checkbook in technical jargon. Have the past changes explained to you and show you the service booklet or an invoice from the workshop.
- use room for negotiation: The toothed belt change is due shortly after the purchase? This subsequently drives up the purchase price. Use this cost item in your favor and suggest a reasonable discount. If the checkbook leaves questions unanswered, a visual inspection of the workshop is also recommended. This cost factor should also be reflected in the purchase price.
Conclusion: No experiments with the toothed belt
The toothed belt connects the crankshaft to the camshafts and transfers the kinetic energy to the transmission and finally to the road. Its function of synchronizing the processes in the engine is elementary. And that for many 10,000 kilometers. As reliable as it is: When changing the timing belt, it is forbidden to experiment. If you want to rule out engine damage, it is better to drive to the workshop sooner than later.
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