Difference between timing belt and timing chain

MOTOR MART  MOTOR VEHICLES

Much as the two might sound different, they practically carry out the same purpose - linking the crankshaft and the camshaft to control the engine valves and timing.

The physical difference is in the material used. The timing belt is rubber-made while the timing chain is metallic.

Omar Ahmad, the workshop manager at Spear Motors Limited says the timing chain does not need servicing, nor change but the timing belt has to be changed depending on the manufacturer. "Some say you got to change at 80,000km while others say at 120,000km so it isn't standard," he notes.

The timing chain because of the difference in material (metal) has weight making it heavier, than the belt which is rubber.

 "The rubber can be about 200g and the chain about 2kgs. So of course the chain can do more, it is stronger and that is why most high-speed cars have them," he explains adding that most of the time, about 99%, the chain lasts as long as the engine.

 "I have never seen a broken chain yet I have been working with Daimler and in Uganda for 16 years but I have seen a broken timing belt."

Aloysius Kawooya of Cooper Motor Corporation says the timing chain is serviced whenever you do service because it is inside the engine and uses the same oil for the engine.

That partly explains why the timing chain lasts longer than the timing belt. And there are no chances that the timing chain will break. However, he adds that they have specific mileage because if they wear off completely, they can skip a teeth and vehicle fails to start.

A broken chain causes big damage to the engine because of the revolution per minute (rpm) it makes and that can be in thousands so when it breaks, it can damage the engine.

According to Ahmad, Mercedes vehicles specifically use timing chains except only one type that is not here in Uganda that used a timing belt. So, if you are driving a Mercedes, you don't have a belt to worry about.

However, he explains that the rubber used is no ordinary rubber but has been mixed with some material to make it flexible and durable so the recommendation is not only mileage but also time.

 "Some manufacturers say after six years you have to change your timing belt or after 80,000km and so they don't tell you only the mileage but also the time because it begins to lose elasticity and then crack and break," he adds.

The ideal practice is for the car owners to change the belt because if it breaks, for the case of chain, it can spoil other parts of the vehicle that can shoot up the repair bill because you will spend more fixing the engine too.

Kawooya explains that for the belt, when the time to change comes, which is at about 100,000km, you will have issues. On some vehicles, they don't warn you but just break and create damage.

According to him however, he says the timing chain does about 150,000km and if it breaks, it knocks the valves and damages the engine.

 "This is because there is a crankshaft which drives the pistons and camshafts are driven by the belt so if in case it breaks when the vehicle is in motion, there is that extra force pushing them towards each other," he explains adding that these days vehicles have chains instead of belts like all the new Ford vehicles.

Does the engine affect the belt performance?

Ahmad says it depends on how the car owners treat their vehicles, citing where the vehicle is serviced and the type of oil. He says the wrong oil damages the vehicle so the owner has to know the type of oil.

On whether miles travelled affect the effectiveness of the timing belt or chain, he says if you travel more and hit the kilometers as per the manufacturers, it is recommended you consider changing. 

But he notes that you will have to travel long distances because engines are designed to travel long distances, it needs the heat, temperature, the exhaust heat. So, you will have to travel long distances at least once in a week to save your engine, and not only the belt.

Kawooya says miles travelled does affect the timing belt or chain unless there is a problem. He explains that every time service is done, the mileage is registered on the service card and so can be monitored by the car owner on how much is left before the next service. 

Also adding that that is how you time the belt also because it might not break at 100,000km or 130,000km but disappoint you at 150,000km. The manufacturers give the about 10,000km allowance after it starts warning so you can get ready and fix it.

On one being noisier than the other, Kawooya says the beauty about the timing chain is when it is about to break it will make noise for about 10,000km unless you aren't a good driver to listen.

Ahmad says the belt is quiet compared to the chain but the fact is, a diesel car will be louder than petrol regardless of whether it is belt or chain.