Timing is the process of synchronizing the camshafts with the crankshaft. This allows air to enter and exit the engine at a specific time. This also tells the ECU when to fire each spark plug for optimal combustion.
Use of modern vehiclestoothed chains instead of toothed belts. While timing belts need to be replaced every 60-80,000 miles, timing chains are usually designed to last the life of the vehicle. Timing chains will only be serviced if there is a problem or if they are removed for other engine work.
Contents
How the timing chain works
Timer chains work a bit like bicycle chains. If you've ever ridden a bike, you know that a chain connects the pedals to the rear wheel. When pressed, the torque is transferred from the pedals to the rear wheel via a chain.
AlreadyFiretakts enginewith a toothed chain, the torque of the crankshaft is transmitted through the toothed chain to the camshafts. The timing chain is also responsible for maintaining perfect synchronization of the crankshaft and camshafts.
This allows the valves to open and close at exactly the right time for each piston as the pistons move up and down.
Symptoms of a bad timing chain
1) Chain noise during startup
When you want to start the car, you should not normally hear the toothed chain. If you hear an unusual rattling or grinding noise when you start the engine, but it goes away after a while, there may be a fault in the timing chain component.
Remember that some vehicles make more engine noise than others, so you'll want to listen for new sounds that emerge. If you've had the car for years and it always makes the timing chain rattle a little, it might be okay. It never hurts to check the vehicle if you are unsure.
2) Misfiring or irregular idling
Timing chains optimize the combustion process by controlling air intake and exhaust in the combustion chamber. If you have a toothed chain that has snapped a tooth, the valves may be open or closed when they shouldn't be. it causesthe engine runs unevenly,especially when idling.
3) The engine does not start
If the timing chain broke, you willwill not be able to start the engine. Without the timing chain, there is no way to lift the intake valves to bring fresh air into the engine or remove the exhaust fumes.
What causes timing chain noise?
Timing chain noise is often caused by a loose timing chain tensioner. The toothed chain tensioner is responsible for tightening the slack on one side of the toothed chain.
Hydraulic tensioners
Many chain tensioners are hydraulically actuated. These engines have an oil passage that runs through the front of the engine to a small piston. When the oil is pressurized, the piston applies pressure to the timing chain tensioner and removes the slack from the timing chain.
Ifoil change intervals are skipped, the oil passages leading to this small piston can become clogged, preventing the piston from removing the slack from the timing chain. This increases chain noise.
Mechanical tensioners
There is another type of timing chain tensioner that is mechanical instead of hydraulic. Mechanical tensioners use a spring and pawl instead of hydraulic pressure.
The spring exerts pressure on the tensioner piston, and this piston presses on the chain guide. The pawl then locks the tensioner in place. This holds the chain guide in place with something a little more durable and reliable than spring pressure alone.
Since the distance between the teeth of the pawl is small, the tensioner piston can stop in several slightly different positions after the engine is switched off. The engine can stop when the timing chain rests vertically against the pawl, or it can stop with a slight slack in the tensioner.
If the tensioner is slightly loose, it can lead to a slight noise from the timing chain on first start for a fraction of a second.
Related:6 causes of timing chain noise
What causes the timing chain to break?
Bad timing chain tensioner
A bad timing chain tensioner leads to a loose timing chain. This puts a dynamic load on the chain when starting and stopping the engine, which increases wear if it exceeds the tolerances for which the chain is designed. Over time, this can cause the timing chain to break due to the added stress.
Damaged timing chain guide
A broken timing chain guide can cause the timing chain to move out of position. This will break the timing chain if it contacts another component or disengage from the timing sprocket if moved too far out of position.
What happens if the timing chain breaks while driving?
If the timing chain breaks while driving, the engine stops and the car stops. You will not be able to drive again until the timing chain is replaced.
Please note that some vehicles can suffer serious engine damage if the timing chain breaks. It depends on whether the engine is collision type or non-collision type.
An interference engine is an engine where the pistons and valves can come into contact if the vehicle is not properly aligned.Valve-to-valve or piston-to-valve contactwill likely destroy the engine.
When should the toothed chain be replaced?
While a timing chain typically does not stretch or wear over timelike a timing belttoothed chains may need to be replaced under certain circumstances.
If a component in the timing chain assembly has failed, such as a chain guide or tensioner, it is often recommended to replace the entire timing chain assembly. This includes the timing chain itself.
Some manufacturers may recommend replacing the toothed chain if it needs to be removed for other work, such asvalve operation, replacement of the front main seal etchead gasket replacement. If you are doing this job yourself, check your factory service manual to see if timing chain replacement is recommended.
If you take your vehicle to a repair shop, your mechanic should know how to replace the timing chain if necessary and estimate the additional labor.
Timing chain replacement
Looking for spare parts?
We recommendDele freakat the best prices and selection.
The cost of replacing the timing chain will vary depending on the year, make and model of the vehicle. Expect to pay about $1,000 to $1,600 for this maintenance at an independent shop.
Do you have to replace the timing chain yourself?
Because timing chains do not require regular servicing, they are often more difficult to replace than a conventional timing belt. Do not attempt to replace the toothed chain yourself unless you are qualified to do so.
This work is best left to a professional with some experience. This is especially important if the vehicle is equipped with a collision engine.
- Author
- Latest Posts
Sean
Sean is an avid car enthusiast who maintains his own fleet of vehicles and wants to help others do the same. He has completed many hours of professional training in driving licences, he is a memberSCCAand takes the art of driving seriously. Thoughtful and skillful driving can save many lives. Sean can often be found on the racetrack, autocross course or during mountain competitions.
Sean's latest post(it's different)
- Over 140 different car parts (glossary and guide)- 1. august 2023
- How to replace a car thermostat (in 15 easy steps)- July 12, 2023
- Check if the VSA light is on (5 reasons and what it means)- 28. June 2023
FAQs
3 Signs of a Bad Timing Chain (and Cost to Replace in 2023)? ›
The average cost for a Timing Chain Replacement is between $1,648 and $1,908. Labor costs are estimated between $950 and $1,198 while parts are priced between $697 and $709.
How much will it cost to replace the timing chain in 2023? ›The average cost for a Timing Chain Replacement is between $1,648 and $1,908. Labor costs are estimated between $950 and $1,198 while parts are priced between $697 and $709.
Is there a warning before a timing chain breaks? ›Check Engine Light
Often, this diagnosis is the first step in replacing the timing chain outside of regularly scheduled maintenance. For many people, the check engine light is the only warning sign that there is something wrong before the chain snaps.
Timing chains are tricky components to come by on the car market. According to theway.com, the average replacement cost for a timing chain averages $1,600 - $1,800 if the job is completed by a professional. If you decide to do the replacement, it will cost $600 - $800. It's not a cheap repair by any means.
What happens if I don't replace my timing chain? ›Metal debris from a damaged timing chain can break and fall into the oil. If the timing chain starts to wear out, small pieces of metal can break off the chain and get into the oil pan. These small shavings of metal are observed when changing the oil and oil filter, which can lead to premature engine failure.
How long can you drive on a bad timing chain? ›How long you can drive with a bad timing chain depends on the severity of the problem. But, if your bad timing chain is on the verge of failing, you might only be able to drive a few more minutes. Once your bad timing chain fails, you'll immediately lose the ability to operate the vehicle.
What does it feel like when your timing chain is going out? ›Misfiring Engine
Since the timing chain times the opening and closing of engine valves, any damage can unbalance the air-fuel ratio and result in a lack of power. It appears as a jerking motion and loss of acceleration.
A stretched timing chain contributes to poor engine performance and increased emissions, triggering the check engine light and the storing of a diagnostic trouble code. A mechanic will need to inspect the code and prescribe the necessary repairs.
Will check engine light come on for timing chain? ›a stretched timing chain will hurt engine performance and increase emissions. if this happens, the computer will turn on the check engine light and store a diagnostic trouble code. 2.
What does a noisy timing chain sound like? ›There is a rattling sound. A lax timing chain, or worse, a broken timing chain with loose parts within the engine, will produce a rattling sound when your car is idling. This rattling sound is typically most prominent while the engine heats up and disappears after some time.
How many hours does it take to replace a timing chain? ›
During the combustion process inside the cylinders, camshafts open and close the intake and exhaust valves at just the right time. Overall, it should take a qualified mechanic between 5 and 8 hours to replace the timing chain and all of the parts that go with it.
How many years does a timing chain last? ›A: As a general rule, if an engine has a timing chain and the oil was changed on a regular basis, the timing chain should last the lifetime of the engine.
At what mileage should a timing chain be replaced? ›The timing chain normally needs to be replaced between 80,000 and 120,000 miles unless there is a specific problem. Issues with the chain are common in higher mileage vehicles.
Can a timing chain last for 200000 miles? ›The metal links in the chain move on the tooth sprockets on the end of the crankshaft and crankshaft so that they rotate together. The timing chain normally needs to be replaced between 40,000 and 100,000 miles unless there is a problem.
Will a broken timing chain destroy my engine? ›A broken timing chain will cause an engine to not start or fail while driving. If the belt is already broken, the engine won't have enough compression to start. If it breaks or jumps while driving, the pistons will be damaged from contact with the valves. The valves themselves will bend and potentially ruin the engine.
How much does it cost to replace a timing chain on a 2008 Chevy Colorado? ›Labor costs are estimated between $1,609 and $2,029 while parts are priced between $550 and $559.