Timing belts and timing chains have been present since the early days of the internal combustion engine. There are very important parts of the engine and are responsible for the good operation of the engine. Every car has one type of timing.
There are differences between a timing belt and a timing chain, but for start, they both do the same thing.
What are the timing belt and the timing chain?
The timing belt and the timing chain are engine parts responsible to synchronize the crankshaft with the camshaft.
As I said above timing belt and timing chain have been present since the internal combustion engine first appeared, especially the timing chain. Back then, the newly internal combustion engine was equipped with a timing chain, ever since 1890.
This was until 1940 when the Americans from Pontiac released a 6-cylinder engine fitted with a rubber strap instead of the classic chain.
This was followed by an explosion of engines equipped with timing belts, the big manufacturers started using the new invention for several reasons.
But why are both types present today, instead of just one and good?
Advantages of a timing belt
- Let’s start with why the belt is good. First of all, the timing belt, because of its material, is much cheaper to produce and to buy made of rubber and not a stainless steel material like the timing chain.
- Another advantage is that engines that have timing belts are much quieter, getting rid of that metal with metal contact which was obvious in older car models with timing chains.
- The belt is slightly rotated on roller bearings. This is how high-powered, 8- or 12-cylinder engines appeared, achieving the performance of having no vibration at idle.
- The timing belt has no need for lubrication, an aspect that is critical for the timing chain, it can run clean.
- Weight advantage. A timing belt kit is much lighter than a timing chain kit
- There is no stretching due to wear
- a wide speed range
- Resistant to chemicals
- Resistant to rust
- No slippage problems
- Up to 98% high mechanical efficiency
- Transmissions efficiency is not lost
Disadvantages of a timing belt
- Requires more attention from the driver
- In some engines, it depends on the water pump
- Requires to change more often
Advantages of timing chain
The timing chain has had its ups and downs, being the first to equip the internal combustion engine, and then had a huge decrease when the timing belt appeared. Timing chains were present mostly on cars with bigger engines.
But immediately after 1990 timing chains began to have a huge comeback, the fact that they last much longer than a timing belt was, maybe, what brought it back into close attention.
Car manufacturers like BMW, Volkswagen, and Mercedes-Benz began to put timing chains on more and more models, even on smaller cylinder engines.
There were also some models that had problems with the timing chains like the n47 engine from BMW and 1.2 TSI from Volkswagen that was replaced with a timing belt later on.
As for advantages:
The timing chain lasts a long time
Because it’s made of metal some car manufacturers say that it does not have to be changed at all, and I think that is partially true, if you take good care of the engine, especially if you put the proper oil in it. But there are also exceptions.
Others say that you should change the timing chain around 250,000 – 300,000 kilometers (155.000 -200.000 miles). Here the timing chain has an advantage over the timing belt, which requires change between 60k kilometers (35k miles) and 100k kilometers (60k miles)
Before it fails, it gives you a lot of symptoms
Another advantage is that when it needs to be changed, the timing chain has some symptoms like loud and weird noises coming from the engine. To better understand, this video below is a good example of these symptoms.
When you change the chain, you don’t need to change the water pump
This is also another advantage that the timing chain has over the timing belt. When changing the belt the water pump will need to be changed also in the majority of motors that have belts.
Even if it is made of many links, a chain does not work and does not change its length depending on the temperature. What does this mean? It means that a much smaller tensioner is needed for the chain, but also that the risk of breaking is lower.
The chain does not slip
Unlike the belt that could jump from the spot, the chain does not slip. It could happen that oil flows on the belt and slips off the pulley. This will lead the belt to jump from the spot followed by malfunctioning the engine.
It could even lead to its total failure if we drive for a long time with the car that makes strange sounds from the engine. The chain stays fixed and does not slip, hence the ability to cope with higher powers.
Disadvantages of timing chain
A disadvantage of the timing chain is the one you could clearly hear. A timing chain makes noise, unlike a timing belt, because it’s obvious that metallic parts come into contact.
However, modern engines that are equipped with timing chains are not that noisy anymore thanks to advanced technology.
Even if the timing chain lasts more than a timing belt, when it needs to be changed, a timing chain kit costs more than a timing belt kit. This includes both the price of the timing kit itself and the labor because chains are more difficult to change than belts.
Timing chains need lubrication
To have a long-lasting operation, the timing chain needs to be lubricated, so if you have a motor equipped with a timing chain, you need to be very careful with the type of oil you put in your engine.
The better the oil, the more the engine will last and the timing chain as well. This guide can help you choose the best type of oil for your engine.
The chain’s tensioner is based on hydraulic pressure
The timing chain’s tensioner works based on hydraulic pressure and this can be a problem, unlike the belt that has mechanical tensioners, tensioned using a spring or a buffer.
The problem with the hydraulic chain tensioner is that if it did not receive immediate pressure, the chain will widen and it will vibrate until it will become very noisy.
Thus driving with old oil in the motor or if it does not have good pressure, the tensioner will not work properly and that will be problematic.
What happens when a timing belt or a timing chain fails?
To answer this question, first of all, we will need to find out what type of engine the car has. Whether the engine is an interference engine or a non-interference engine type.
What is an interference engine?
An interference engine is a type of engine in which, the maximum position of the piston exceeds the maximum opening level of the valve. The valves are synchronized with the position through the belt and do not hit the piston because of a gap, but if the belt or chain fails, the piston and valves will spin independently and will definitely hit.
What is a non-interference engine?
A non-interference engine is a type of engine that does not suffer any damage even if the timing belt or timing chain breaks. Because the valves, even at the lowest position, never reach a position in which the pistons rise.
So even if the piston and valve move chaotic, they are not likely to touch each other because of that gap.
If a timing belt or timing chain fails and you have a non-interference engine, you will likely need to replace only the timing belt or chain kit and you are good to go.
However, if the belt or chain fails in an interference engine, the damage caused may be much greater. A belt, being made out of reinforced rubber can do less damage compared to a failing chain.
It does not have the power to break even the protective housing.
However, you will have to replace the pistons and valves, which will hit each other. This means expensive labor and expensive parts, besides the new timing kit.
A failing timing chain in an interference engine does greater damage. The chain is a heavy metal piece, which, if it breaks, can damage the engine block, the cylinder head, and even bend the crankshaft.
Usually, if the chain breaks, you will likely need a completely new engine.
Here you can see an animation of interference and a non-interference engine
Timing belts and timing chains have their advantages and disadvantages. To summarize, belts are quieter and cheaper than timing chains. They do not need lubrication but last less than a timing chain.
Chains on the other hand are noisier, but more expensive in terms of costs and labor when they need a change. And are also more durable if you take good care of your engine. It’s up to you to decide what suits you well.