The timing chain is part of a vehicle's engine and its role is to synchronize the rotation of the crankshaft and camshaft at the bottom and top of the engine. This helps the intake and exhaust valves of the engine to open and close synchronously at precise intervals with every engine revolution.
In general, it acts as a link between the top of the engine (cylinder head and valves) and the bottom (pistons and crankcase). This element is similar to the chain in a bicycle and makes more sound than the timing belt.
Correct timing between the valve timing and the strokes occurring in the cylinders is a prerequisite for good engine power and overall performance as well as economical fuel consumption.
Since the crankshaft of four-stroke engines rotates twice as fast as the camshaft, a system is needed to synchronize them. This system can be of several types and include several different elements:
- Timing belt for connecting shafts;
- Gear transmission;
- Timing chain connecting the teeth of the camshaft pulleys and crankshaft.
Consider these systems: their advantages and disadvantages:
Gear transmission. There is a lot of noise in direct engagement and internal power loss occurs. This type of system prevailed in the early 20th century.
Chain drive... The timing chain makes a quieter sound than a direct drive, but makes more noise than a timing belt. The disadvantage of the timing chain is that it stretches after a certain distance. As this chain is stretched, scratching and knocking sounds can be heard, as well as a mismatch between opening and closing valves and ignition. Damage to the timing chain tensioner can lead to the fact that it generally subsides during the operation of the motor.
Belting. Timing belts, on the other hand, are common in cars with modern engines. They are quieter compared to chains and direct drives. They also have less friction, which helps to achieve less engine power loss. The service life of belts depends on the materials from which they are made.
They are made of synthetic rubber and have extra Kevlar fibers to keep the belt from stretching and also ensure proper synchronization, which allows for more mileage.
Differences between a chain and a belt
One of the main differences between a timing chain and a timing belt is that a timing chain can cause more damage if broken than a timing belt. When the timing chain breaks, it causes irreparable damage to the engine, which subsequently becomes practically unusable.
Another difference between the timing chain and the belt is that the chain tensioners are controlled by the engine oil pressure. Since good timing chain lubrication depends on the quality of the oil, it is important to change it periodically. If the level drops too much, the tensioners will lock and the timing chain will also be damaged.
The advantage of this timing system is that it does not interact with the water pump, and therefore we do not need to replace the water pump along with the timing chain.
In its function, it resembles a timing belt, but is more durable. While some manufacturers claim that the timing chain can become obsolete along with the vehicle itself, others recommend frequent replacement.
Manufacturers recommend changing the chain periodically - after about 100-200 km. More precise regulation depends on the car model and the quality of the chain used. Timely replacement of the timing chain ensures optimal engine performance. This procedure will also prevent damage to the engine (in some cars, if the chain is broken, the piston bends the valve, which leads to a major overhaul of the engine).
It is recommended to replace the chain together with rollers, tensioner and gears, as it is not recommended to put a new timing chain on already worn rollers. It is best to take all the elements in a set to avoid the possibility of incompatibility between parts.
When the timing chain breaks at low speed, it can simply slip off the pulleys and not cause serious damage. But if it breaks at high engine speeds, the chain will damage everything nearby. The consequences are difficult to describe in advance, since during a gust the chain can fly into several parts and touch various attachments. After that, the car can be repaired, but it will not be cheap at all.
Poor engine performance and knock are warning signs of damage to the timing chain. Unlike this element, the timing belt does not show any preliminary signs of damage, and its rupture occurs suddenly, after which the valves bend and the pistons collapse, which guarantees us an expensive repair.
For these reasons, correct and timely maintenance is important and prevents engine damage.
It is recommended to regularly check the condition of the drive in accordance with the manufacturer's instructions, and strictly observe the timing chain replacement intervals.
Care must be taken when replacing the timing chain as this also determines how the engine will operate. If the timing chain is installed incorrectly, the engine will also not run properly. The repair must be done exactly.
Drive elements must always be changed in accordance with the recommendations for our vehicle. Buying quality parts will certainly extend the life of your timing chain.
Replacing the timing chain: step by step
The chain replacement procedure includes the following actions:
- Disassembly of protective covers;
- Gearbox blocking;
- Chain replacement;
- Replacing dampers and chain tensioners;
- Replace the oil pump if necessary;
- Installation of protective covers.
Symptoms of a damaged timing chain
A faulty timing chain can damage the crankshaft, camshaft, pistons, and cylinder walls.
One of the signs of damage to the timing chain is knocking, which cannot be ignored, as well as loss of power, difficult ignition, idling. Loss of power is another sign of an extended timing chain.
When the timing chain is damaged, it will disrupt engine operation. Because of this, fuel consumption may increase, as well as the level of harmful substances in the exhaust.
Slackening the timing chain can damage other components in the immediate vicinity.
Excessive tension and possible breakage of the timing chain can cause some problems such as damage to the engine valves. If the timing chain is broken, the engine will not be able to start.
Also, damage to the timing chain can lead to overheating of the engine. Since the water pump is driven by the timing chain, loosening the timing chain will disrupt the operation of the water pump.
When a tooth on a gear breaks, the chain can slip, causing the valve timing to shift and the valves can come into contact with the pistons. This damages the piston crown and causes the valves to bend, leading to major engine repairs.
If during the check we notice that the timing chain is very tight, then it is better to replace it with a new one until it breaks. It is important to know that improper installation of the timing chain can also cause serious engine damage.
Since the replacement of the timing chain has many nuances (you need to correctly set the position of the crankshaft and camshaft), it is recommended to entrust this work to a professional service center.