Timing Chain
A timing chain is a chain of metal links that helps keep the timing of the camshaft and crankshaft in sync. It’s connected to the end gears of both the crank and camshaft(s). Once the crankshaft rotates, the chains transfer that rotational force to the camshaft gears, thus turning the camshaft(s). Since the rotational force comes from the crankshaft and is transferred to the cams, you can see that both rotations can be lined up and consistent because they are connected and synced by the timing chain.
The basic performance of your engine relies on how well air and fuel can be processed through it. The more air and fuel your engine uses for combustion, the more mechanical power it makes. The timing chain is a key factor in how air and fuel are processed through the engine.
Air and fuel enter and exhaust exit the combustion chamber of an engine through the intake and exhaust valves. The timing of when these valves open and close for the entrance, compression, and exit is one of the main factors in making engine power, and the timing chain is in charge of opening and closing these valves in unison with the crankshaft. The crankshaft works the pistons for that same compression mentioned earlier. It’s a full circle/cycle.
What you will learn:
Timing Chain vs. Timing Belt: Key Differences
A timing chain is just one of the methods used to keep timing in sync between the crankshaft and the camshaft. The timing chain uses metal links hooked onto the teeth of the end gears from the crank and camshaft. Once the crank turns, everything else the chain is hooked onto turns as well. Another method, a timing belt, uses the same philosophy, but executes it differently.
Instead of chains and gears, it uses a belt and a series of grooved/riveted pulleys connected to the crank and camshaft. A timing chain is made of small metal links that accommodate the gear teeth, whereas a timing belt is made of an assortment of natural and synthetic rubbers, such as “Neoprene & Nitrile”, and certain plastics, such as “PVC & Urethane”.
Timing chains are housed within the engine block unit and require quality, clean oil for operation. This setup makes the lifespan of a timing chain much longer than a timing belt. Timing chains can last the lifespan of an engine with proper maintenance, although manufacturers make them to last up to 150,000 – 300,000 miles.
Timing belts sit outside of the engine block, so no oil is needed for lubrication. However, although durable, timing belts do not last as long as timing chains and need to be replaced more often as they wear. Due to materials advancements, timing belts can last 60,000 – 100,000 miles, depending on vehicle make and model. Although the lifespan is lower compared to timing chains, it is also very durable.
Early on in the history of combustion engines, cars used timing chains. The industry transitioned into using timing belts as they realized they were quieter than timing chains. Not only are timing belts quieter, but they are also lighter, which brings more benefits to high-revving engines.
Common Symptoms of a Failing Timing Chain
A timing chain’s main purpose is to keep the timing of the engine’s crankshaft and camshafts in sync. So for a failure of this component will affect the engine timing negatively, essentially making the engine run very rough and inefficient. In certain cases, this failure can lead to severe engine damage.
Here are some common symptoms of a failing timing chain :
- Engine rattling, especially during startup or acceleration.
- Engine misfires, rough idle, engine stalling, or reduced power.
- Metal debris in engine oil indicates excessive wear.
The check engine light is also a symptom of timing issues. The code derived from a check engine light can point you in the right direction of what issues with engine timing are present. A couple of Check engine light codes related to timing chain issues are P0016 & P0017.
When and Why Does a Timing Chain Get Damaged?
For a timing chain to run efficiently and live a happy, long life, it needs a couple of things. One of those main things is engine oil. The timing chain operates with metal-to-metal contact, and things can get hot quickly. Engine oil is used to lubricate the areas of the timing chain that need it to reduce friction. If too much friction builds, things will get hot quickly and can lead to serious engine damage. For engines with timing chains being on top of frequent oil changes are crucial to the good health and efficiency of the engine, especially the timing chain.
The other thing a timing chain needs is good tension. Most timing chain engines come with a hydraulic tensioner. These are guides at specific points in the timing chain that add pressure to keep the chain tight. A loose chain can bring serious issues, which is why there is a need for tension. Loose chains rattle, skipping the teeth on the gears, causing misalignment between the crank and camshafts, which can cause catastrophic failure of your engine. Timing chains also stretch over time due to high mileage and wear. At this point, the chain needs to be replaced before further damage occurs.
NOTE: Conditions that accelerate timing chain wear in when the engine overheats. A very hot environment can cause the metal to expand, maybe even snap. This is why it is important to be on top of your engine oil intervals, even more so for engines with timing chains.
Maintenance & Replacement Intervals for a Timing Chain
Manufacturers usually make timing chains to last the life of an engine; the time to replace a timing chain is when the chain is too loose or damaged. The number one maintenance necessary for a timing chain is quality clean engine oil. Being on top of your recommended oil chain oil change/service intervals, and sometimes quicker than recommended, will keep your timing chain in good condition for the life of the engine. Service intervals with allow the professional mechanic to see if there are any issues upcoming or apparent for the timing chain and its components.
Timing Chain Replacement Cost and Considerations
The average cost for a timing chain replacement can range from $2,000 to $2700, depending on the vehicle make and model. Timing chain OEM parts can cost $300 – $1500, while the labor for installation can be $500 – $1,500. The importance of service intervals and oil changes is to catch any early detection of timing chain issues before repairs become too costly.
FAQ
- What is the purpose of a timing chain in an engine?
The purpose of a timing chain in an engine is to keep the timing/rotation of the camshaft(s) in sync with the rotation of the crankshaft. This ensures the opening and closing of the intake and exhaust valves operate with a specific time that’s connected to the engine’s cylinders for proper engine combustion.
- How often should a timing chain be replaced?
Timing chains are meant to last the life of the engine, but they may require a replacement between 80,000 – 120,000 miles, depending on the vehicle make, model, and driving conditions. Another time to replace a timing chain is when it is either damaged or stretched.
- What are the signs of a failing timing chain?
Signs of a failing timing chain include:
- Engine misfire
- Engine rattling noises (especially on start-up)
- Metal shavings in the engine oil
- Check engine light (Codes: P0016 & P0017)
- What causes a timing chain to fail?
Factors for a failing timing chain are poor maintenance, lack of lubrication, engine overheating, and natural wear and tear of operation.
- Is it worth replacing a timing chain?
Yes, if you plan on keeping your car longer, a proper timing chain is crucial to prevent engine failure.
