You might be comparing certain specs of cars before deciding which one to buy. What is the engine’s displacement? What kind of brakes does it have? What type of transmission does it use? Does it come with long range AEB? There are a lot of things you could compare between every car before deciding on your purchase. Today, we’ll be talking about timing belts and timing chains.
The timing belt connects the crankshaft sprocket and the camshaft sprocket. Photo source
Timing chains or timing belts are used to synchronize the camshaft rotation and the crankshaft rotation. Most engines of today utilise an Overhead Cam (OHC) configuration so a belt or a chain is required to connect the crankshaft and the camshaft. Engines that use a push rod configuration also need a timing belt or a timing chain (although shorter in length).
A push rod engine. Push rods still use a camshaft and a timing belt/chain/gear. Photo source
Some argue that timing chains are better because they last longer. Some argue that timing belts are better because they are cheaper to replace and are quieter. The thing is, you can’t choose whether to have a timing belt or a timing chain in a car you are about to purchase. You’d have to get a different car if you preferred one timing system over the other.
Take for example, a Perodua Myvi and a Proton Iriz. A Myvi comes with a timing chain while an Iriz comes with a timing belt. Does it make one car superior to the other? Is one cheaper to maintain than the other?
Let’s go through a few questions and find out.
Q: What is a timing belt?
A: A rubber belt that is driven by the crankshaft and drives the camshaft.
Timing belt
Q: What is a timing chain?
A: A chain that is driven by the crankshaft and drives the camshaft.
Q: Which is better? Timing chains or timing belts?
A: Timing chains are stronger than timing belts. Timing chains also last longer. Timing belts are quieter than timing chains and are cheaper and easier to replace.
Q: Are timing chains more expensive than timing belts?
A: Yes. Usually not by much. Changing the timing chain also requires changing some gears since the gear teeth are worn out too. However, timing chains do not need to be changed as frequently as timing belts.
Q: Do timing chains last longer than timing belts?
Q: Are timing chains harder to replace than timing belts?
A: Yes. Timing chains need to be lubricated by the engine oil. Hence, they are in a more enclosed housing. This means extra work just to get to the timing chain. Timing belts are usually only protected by a plastic cover and are more accessible for maintenance work.
More parts need to be disassembled to access the timing chain. Photo source: Borneo Auto
Timing belts can be accessed by removing the plastic cover. Timing belts do not need lubrication.
Q: Does using a timing chain or a timing belt affect fuel consumption?
A: No.
Q: Does using a timing chain equal better performance?
A: No.
Q: Do timing chains wear out?
A: Yes. The gear teeth and sprockets mesh. The gear teeth eventually wear out and the chain eventually stretch becomes looser and longer. You eventually have to replace them. However, there is no specified interval for a timing chain replacement.
Timing chains become stretched over time and could jump gear teeths. Photo source: Road Race Engineering
Usually the engine warning light will light up when the timing chain stretch could potentially damage the engine. Stop the engine if that happens. Chain stretch could cause the chain to jump a gear tooth and disturb the synchronization between the pistons and valves and cause some rough idling.
Q: Do timing belts wear out?
A: Yes. That’s why they need replacing every 100,000 km or so. Unmaintained timing belts can snap and cause catastrophic damage to the engine (especially interference engines). Timing belts could also slip due to worn out teeth.
This is the case with interference engines that are more efficient and compact in design. Timing belts have a higher tendency to snap, but usually if you keep it replaced on time, such a problem should not happen.
When out of sync, valves and pistons may collide. Photo source
Q: Do high performance cars use timing chains or timing belts?
A: It’s a mix. An older RB26DETT uses a timing belt. A newer VR38DETT uses a timing chain.
Timing chain in a Nissan GTR
Some cars like the Ferrari Enzo don’t even use timing belts or timing chains. Instead, they use a bunch of timing gears to synchronize the valves with the engine rotation. Timing gears are noisier than timing chains.
Timing gears in a Ferrari Enzo
In summary:
Timing chains last longer than timing belts, but they are a bit more expensive.
There are no performance gains or fuel efficiency gains if you use one over the other.
Cheaper cost was the main reason for the use of timing belts in cars. They work just as fine.
Timing chains can stretch over time and cause "jumping" of gear teeth
Timing belt teeth can wear out and slip. Timing belts also have higher risk of snapping.
Failure of timing belt or timing chain can be catastrophic to the engine.
An added benefit of timing belts is the quieter operation noise.
Whatever timing system your car is using, perform regular servicing to monitor the health of your timing belt or timing chain.
Previously an engineer in an automotive manufacturing company and a highway concessionaire. A part-time research student on biofuels and diesel engines. Obsessed with vehicle electrification and the future of transportation.
