What is a Timing Belt or Timing Chain?

A large portion of drivers in the area of Northern Virginia have heard the words “timing belt”, but don’t have a true idea of what it is, how it works, and what it means for the engine if it ceases to function properly.

The team at Casey’s Automotive in Sterling, VA is here to drop some knowledge bombs! In the following blog, we will give you a better understanding of what a timing belt is, how a timing belt functions, and the warning signs of an impending failure.

What is a Timing Belt and or Timing Chain?

The engine goes through a 4-phase cycle in which the air and fuel that enters are compressed, fire or explodes, and finish after exiting the engine in the form of exhaust. This cycle is represented in many cars by RPM’s (Revolutions per minute). When a cycle is completed that’s one revolution. To do this, it must go through a cycle over and over again.

Think of your engine in two halves, an upper and a lower. The lower half is pistons and a rotating assembly called a crankshaft. The upper half is a set of valves and a rotating assembly called camshafts. These components need to be in sync at all times and rotate together either by a chain or by a rubber belt. 

An easy analogy is a bicycle and the chain that goes from the front crank to the rear wheel. As you spin the pedals it turns a gear pulling a chain which, in turn, turns the rear gear, therefore, turning the rear wheel. Timing chains and belts are similar.


There are two types of valves in a 4-cycle engine. Intake valves allow air to enter into the engine and exhaust valves allow combusted gasses to leave the engine. These valves act as a doorway. 

The valves open at the correct time to allow the passage of gasses, and they close at the correct time to seal off the cylinder for combustion to take place. Valves are operated by a camshaft which rotates with the movement of a timing belt or timing chain, which is operated by the rotational movement of the crankshaft.

Without a fully functioning timing belt or chain, an engine will not run. The timing belt or chain is a component that acts as a link by wrapping around a part of the camshaft and the crankshaft. Its job is to keep the camshaft and crankshaft synchronized so that the timing in the intake valve is consistently correct.

When the timing belt ceases to function properly, by becoming loose, stretched, or the teeth on the belt cease to grab and hold onto the gear, it causes the camshaft and crankshaft to fall out of sync. This can be catastrophic to the engine. If the timing in the valves goes bad, the engine valves will open at the wrong time and the pistons may come in contact with them resulting in catastrophic damage. 

Over time, a timing belt will wear down and lose efficiency, requiring maintenance. Timing chains on the other hand require less maintenance as they are lubricated by the vehicle’s oil system. Manufacturers have a recommended schedule for every vehicle, but it typically requires replacement at 100k miles. Chains eventually do wear out but typically not for hundreds of thousands of miles. 

Warning Signs of Timing Failure

Given the importance of a fully functioning timing component within the engine, pay attention to it. Here are a few warning signs you should have knowledge of so that if any of them crop up, you will be able to recognize the immediate need to contact Casey’s Automotive in Sterling, VA.

The engine is making a ticking sound. Since the timing belt works as a pulley system for the crankshaft and camshaft, if it goes off-kilter, you might hear it click while it is running.

The engine will not start. It will turn over or crank but never catch and actually run. Sure, you might hear the starter motor engage, but it will not fully start.

The engine misfires. When the belt or chain grows too worn, it can impact the engine. When the belt slips on the camshaft drive, it can cause multiple cylinders to close or open earlier than it should. That is what causes the engine to misfire.

Timing chains, since lubricated by the engine oil, may develop a leak at the timing cover. The cover over it is secured with nuts and bolts but may come loose over time causing engine oil to seep out. The other cause of leaky oil comes from a gasket between the engine block and the timing cover. It too can wear over time. Or become cracked. If oil leaks from any of these areas, it can cause damage by prematurely wearing out the timing chain.

Timing Belt Replacement in Sterling, Virginia

No matter what the symptom or cause, ensuring the timing belt or chain in your vehicle is working at its full capacity will assist the longevity of your car or truck. If your vehicle has passed 100k miles, or you suspect there is a timing issue, contact the certified team at Casey’s Automotive. When your vehicle comes into one of our locations, it is given a complimentary inspection that covers 42-points! The digital inspection is sent directly to your phone and includes photos and detailed descriptions. We have got your back!







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