The Identifying a Failing Timing Chain. Timing chains are an important part of engine timing. The opening of the intake valve is the first “stroke” in a typical four-stroke engine. As the piston descends, the intake valve opens, allowing air and fuel into the cylinder. The piston returns to its starting position, compressing the air and fuel, and the intake valve closes. The spark plugs then ignite, causing combustion and sending the piston back downwards, where the exhaust valve opens, allowing air to exit the cylinder.
Engines must function properly if the timing of the intake valve opening/closing, combustion, and exhaust valve opening/closing is precise. The timing chain is in charge of ensuring that the valves open and close at the proper times.
Timing chains are an item that must be maintained. They deteriorate and stretch over time, causing a variety of performance issues and even catastrophic engine damage. This article will go over timing chain function and how to tell if your timing chain is failing.
What exactly is a timing chain?
A timing chain controls the opening and closing of an engine’s intake and exhaust valves. A set of gears, usually located on the front of the engine block, connects the timing chain to the camshaft and crankshaft.
The camshaft rotates once every two crankshaft turns. As the camshaft rotates, small lobes known as cams push up against the valves, causing them to open.
Here’s an example of a timing chain system, complete with chain, guides, tensioners, sprockets, and so on.
Additional Timing Chain Details
Because the timing chain is made of metal and turns on metal gears or sprockets, it requires oil lubrication. As a result, the timing chain is protected from road dirt and debris by a timing chain cover, which bolts to the block and lubricates it with engine oil.
The timing chain also has timing chain guides to keep it on track and prevent it from slipping off the sprockets.
A tensioner is the final component of timing chains. The timing chain tensioner ensures that the chain is not slack. The majority of tensioners are spring-based and hydraulically actuated, which means they rely on oil pressure to keep the chain tight.
What causes timing chains to fail?
Timing chain stretch is the most common cause of timing chain failure. Because the timing chain is so close to the engine, it gets a lot of heat. The heat gradually causes the metal chain to stretch over time. As the chain stretches, it becomes loose on the gears, causing it to “jump teeth” or even fall off the sprockets.
In addition, low oil levels can cause timing chain stretch. When the metal chain is not properly lubricated, it generates heat and friction because it runs on metal gears. When oil levels fall too low, the chain can be deprived of lubrication, causing it to stretch.
Failure of the Timing Chain Guide
Timing chain guides are also prone to failure. Because the guides are typically made of plastic, they are prone to breaking over time due to heat, engine vibration, and other factors.
When the guides fail, the chain becomes disoriented and can jump teeth or fall off completely.
Related : The Symptoms of Ignition Coil Failure
Chains vs. Belts in Timing
Timing chains, at their most basic, are made of metal and turn on gears or sprockets. Timing belts are made of rubber and do not come into contact with sprockets. Furthermore, chains are housed within a timing chain cover, whereas belts are typically exposed in the engine bay.
Timing chains last longer than belts, but they also have more failure points. Timing chain covers can leak, tensioners and guides can fail, and so on.
Low oil levels and engine overheating are two of the most common causes of timing chain failure. Both of these scenarios will increase the heat and stress on the timing chain, causing it to stretch.
Keeping the Timing Chain from Breaking
- Inspect your timing chain cover for leaks on a regular basis.
- Maintain adequate engine oil levels.
- Do not allow the engine to overheat; if it does, stop driving.
Can I drive with a broken timing chain?
As previously stated, the timing chain spans time. You can drive on an old timing chain, but we recommend replacing it as soon as you notice noticeable stretch and failure symptoms.
If you drive on a bad chain for too long and it continues to stretch, it can jump a lot of teeth or completely fail, causing catastrophic internal engine damage.
Costs of Timing Chain Replacement
Most timing chain components will cost between $100 and $200. Labor is the most variable component. Labor costs typically range from $250 to $1,000, but it can be much higher in some cases.
For example, the timing chain on Audi’s 4.2 V8 is located at the back of the engine, necessitating the removal of the entire engine to be replaced. As a result, this is a $5k+ replacement job.
While this is an extreme example, the point is that the cost of replacement is primarily determined by the difficulty of replacement rather than the cost of the item itself.
