Engine and timing chain - when to change a worn car part? Causes and consequences of damage

The timing drive is a key element of the unit, since it is responsible for the interaction of many nodes. Therefore, it must be reliable and operate at a strictly defined voltage so that the engine does not fail. There are two types of drive currently in use on the market:

• chain,
• striped.

There is also an interesting solution that has recently entered the market and is called Free valve. This name hides a system without a camshaft, which means that there are no classic solutions associated with the presence of a timing chain or belt. The valves are actuated by a pneumatic compressor and do not require cam control. However, it's more of a curiosity than a design you can look forward to in everyday cars in the near future.

Why is the timing chain no longer so strong?

Maybe you still remember the old Mercedes cars? First of all, we are talking about cars marked W123. These cars also used a timing chain and engine displacement often exceeded 2 liters. But why did this solution run even half a million kilometers without fail? For example, the 3.0 D unit had 80 hp. Under the current conditions, this can be considered a bad result. Mainly due to the low effort, these units were so armored.

Of course, power isn't everything. The old engines were not very economical, and the above car could burn more than 9 liters of diesel fuel per 100 km. Solutions to reduce exhaust emissions have made engines more complex. Therefore, the timing chain (although in fact it is a thick and powerful chain) must now work under heavy loads, drive more nodes, use sliders and tensioners. Previously, it was put in two gears and that's it.

The complexity of the system can be seen in the Audi 3.0 TDI with a V6 engine. It is equipped with 3 timing chains, the location of which is not very intuitive. The complexity of the whole solution affects not only the cost of repairs, but also the prices of spare parts. According to the market, the timing chain replacement kit in this car costs more than PLN 2. And that's just the parts.

Replacing the timing chain - what you need to know?

The significant overloads to which the timing drive is subjected means that, depending on the brand, the condition of the timing chain should be checked from time to time. It is subject to wear and tear, which can be caused by various factors.

Why can a timing chain wear out?

You already know the first reason - the huge forces and complexity of the drive units. In addition, the timing chain may wear out due to:

• design defects and the use of unsuitable materials. The tensioner eliminates small differences, but it will not be able to adjust the excessive play. The result of this phenomenon will be a decrease in the power of the unit. The opening and closing times of the valves change, which in a critical case can lead to their collision with the pistons;
• using the wrong engine oil. Unlike a belt, a timing chain is oil lubricated and does not run dry. This is due to the peculiarities of its work, which is based on metal-to-metal contact. Weak oil causes abrasion of the material and faster wear;
• defective gear. Often they are the reason for replacing the timing chain. Therefore, during service work, new wheels are installed. And this, unfortunately, affects the sum of the entire operation.

What is timing chain replacement?

The whole process depends on the design of the unit. First, smaller in-line engines also have fewer timing chains. In many cases, one is sufficient for the entire drive. This reduces repair costs. Secondly, the location of the timing belt. If he is "in front" of the unit, then the matter is not so difficult. The process looks somewhat different when the manufacturer decided to place the timing drive “rear”, from the side of the gearbox. How then to replace it? The engine will need to be disassembled. This means that the price of the entire operation can sometimes exceed 5 PLN.

Timing Chain Replacement and Component Inspection

Of course, the timing chain alone is not everything. The complete also includes checking other components and replacing them. Tensioners, sliders, gears included. Gaskets and seals also need to be replaced. And since the chain runs in oil, you should also get new lube. Replacing individual components individually can only increase the cost of the entire operation, because installing a new timing chain without other parts will not improve the operation of the entire system. You will probably have to perform this expensive operation again soon.

When is timing chain replacement necessary?

As a user of a vehicle with a timing chain, it may be difficult for you to determine the replacement interval. It doesn’t make things any easier that many manufacturers do not indicate in detail when to change the timing chain. Therefore, in certain situations, you are on your own. The key is to watch the drive and listen for anomalies. 

How to recognize a damaged timing chain?

Timing chain malfunctions can be recognized by several signs. First of all, it will be uneven idling of the unit. RPM fluctuations can also be caused by a malfunction in the ignition or intake system. In addition, the difficult start of the unit should also alert you. If you hear a distinct knock on a cold engine that disappears soon, you may suspect a worn tensioner. Another thing is the knock from the timing, which appears in proportion to the engine speed.

Of course, simply finding the above symptoms will not tell you when to replace the timing chain. They don't always mean it's defective. Therefore, first of all, take care of the regular replacement of engine oil. Also use quality parts. This will allow you to avoid unpleasant adventures caused by engine malfunctions.

The timing chain used to be a permanent solution. Now it is not always a symbol of solidity. To check if you have a timing belt or chain, you can look up the vehicle's VIN number and contact your dealer. Another solution is to refer to the manufacturer's specifications. It is also assumed that the timing belt has a plastic case that is easier to remove and the chain is metal. If your car has it, take care of the right oil and change it regularly.