When to Replace the Timing Chain on Your Vehicle

Your car’s engine contains many components, one of which is either a timing belt or a timing chain. Although the timing chain doesn’t get as much attention atims some other car parts, it is extremely important. If the timing chain fails, it can cause an array of problems—including catastrophic engine damage.

Do Timing Chains Need to Be Replaced?

You may be wondering—how long does a timing chain last? Unlike timing belts, timing chains are designed to last the life of the vehicle. Of course, that doesn’t always happen. Timing chains can break for a number of reasons, which we’ll discuss shortly.

Because of the long distance between the crankshaft and camshaft gears, there are nylon guides to prevent the timing chain from making noise; there’ll be a guide on both sides of the chain(s), and one of the guides typically has a tensioner that has a piston-style tensioner, usually driven by oil pressure, but sometimes driven by an internal gas charge. When a timing chain of this design begins to rattle and the camshaft(s) get out of time, it’s usually because one or more of the nylon guides and/or the timing chain tensioner have failed.

When to Change the Timing Chain

Timing belts require routine replacement—timing chains do not. Unless the timing chain is broken, stretched, or otherwise compromised, there’s no reason to change it. If there is something wrong with the timing chain, your car will likely exhibit one or more problems.

Symptoms of a failing timing chain include:

• Timing chain noise
• Engine misfire and poor performance
• Difficulty in starting the vehicle
• Illuminated check engine light
• Engine vibration or shaking when idling
• Engine won’t start

There’s a possibility you’ll hear a noise coming from the area of the timing chain cover. This noise is often caused by a loose timing chain that may be due to a faulty timing chain tensioner, guide or other issues.

More serious problems will start to arise if you ignore the early signs so make sure to give the timing chain a check as soon as you hear a noise coming from its mounting location.

What Causes a Timing Chain to Break

Some timing chains experience accelerated wear due to lack of vehicle maintenance (i.e. oil changes). Timing belts are not usually lubricated by engine oil (except for on some European makes), but timing chains always are. And that makes regular oil changes vital to timing chain longevity.

Should the nylon chain guides or the chain tensioner fail, or should the engine develop a loss of oil pressure so that the tensioner doesn’t work right (as on 5.4L three-valve Fords), the timing chain will be free to slap around against other components; sometimes a loose and rattling chain will rub a hole in the timing cover, necessitating the replacement of the cover.

What Happens When the Timing Chain or Belt Breaks or When the Engine Jumps Time?

Timing chains don’t usually break (timing belts do!), but chains can get far enough out of time so that the vehicle can’t be driven. If you’re driving on the highway, the engine can instantly shut down without any warning. If this happens to you, immediately and carefully pull over to the side of the road while your car still has its momentum. This can happen with any type of internal combustion engine.

Of course, a broken timing belt may have other adverse effects on your engine depending on what type it is. There are two kinds of piston engines you need to consider if you want to know what could happen when your timing chain fails.

For the first part, there is the non-interference engine, also referred to by some as a “free spinning” engine. In this type of engine, the pistons can’t contact the valves even if the engine jumps time. The only thing you need to worry about if you have a non-interference engine is stalling or a serious loss of power, but you’ll definitely need a tow truck.

An interference engine will bend or break valves because the pistons and the valves will impact each other if the engine jumps time. Timing chain equipped engines are ALWAYS interference engines. And again, timing belt engines may or may not be, depending on the manufacturer. So, a jumped chain or belt can call for belt replacement, a valve job, or a replacement engine, depending on engine design.

What is a Timing Chain?

The timing chain keeps the camshaft(s) and crankshaft in sync. For your car’s engine to run properly, the valves, which are operated by the camshaft, need to be timed with the movement of the pistons that connect to the crankshaft. Also, on some vehicles, the timing chain drives other components, such as the water pump and balance shaft.

It’s important to note that not all vehicles use a timing chain. Some cars use a timing belt, instead.

How Much Does it Cost to Get a Timing Chain Replaced?

The cost of replacing the timing chain varies depending on where you’re having it replaced and your vehicle model. Prepare to have a repair budget of around $1,000 to $2,500 for both the parts cost and labor if you’re expecting a timing chain replacement.

If, however, you are the DIY type, you may purchase a timing chain or belt and install it yourself at a price of around $80 to $250. But be aware that some timing chain kits may cost as much as $500 even from the parts store, and are very difficult to replace. A good timing chain kit will come with all the tensioners, the gears, and even a water pump in some cases.

Some timing chains drive the water pump, too, and sometimes the engine must be removed to replace a timing chain. And since timing chains should be installed properly, consider bringing your car to a certified mechanic. There are a lot of other engine parts that must be removed before you even get to the timing chain!

When getting a new car timing chain, most experts recommend soaking it in oil before installing it in the engine to make sure that it’s fully lubricated.

The timing chain is the last to get lubrication upon engine start-up, so this process can help extend the replacement timing chain’s service life.

Timing Chain Installation

The timing chain and gears can be installed after the crankshaft and camshaft are in place, especially in cam-in-block (OHV) engines.

The timing marks must align with cylinder 1 at the top dead center (TDC).

Types of Timing Chains

There are generally two types of timing chains: silent chain and roller chain.

Silent Chain

A silent chain operates quietly but has the tendency to stretch after some time. Also known as a flat-link or Morse type, this chain has metal links that appear to be stretching because the pin bushings at each joint wear out.

An overstretched timing chain will result in a retarded valve timing and might even create an oil leak.

Roller Chain

A roller chain produces less friction and stretch than a silent chain. It turns into a double roller chain if two chains are used side by side.

Timing Chain vs Timing Belt

Timing belts and timing chains both serve the same purpose—and that’s to keep the camshaft(s) and crankshaft in sync. But there are differences. For one, timing belts need to be replaced periodically in accordance with the vehicle manufacturer’s maintenance schedule.

Timing chains do not require routine replacement and should last the life of the vehicle.

There are also differences in design. A timing belt is a large black rubber band that loops around the pulleys and a series of tensioners. It features teeth that hug the grooves around the outer side of the pulley. The belt has either a smooth or patterned outer surface.

Timing chains, on the other hand, are like bicycle chains, only thicker and denser. These are relatively heavier than timing belts as the chain links are made of steel.

Why do some cars have timing belts instead of chains?

Over the past thirty five years, overhead camshafts have become more prevalent; engine designers began to favor timing belts over chains because timing belts need no lubrication and are much easier to replace when replacement is needed. Timing belts typically snake around idler pulleys and a special tensioner, and on most timing belt engines, the timing belt will drive the water pump, and on some, the belt even spins the oil pump (see 2.2L Toyota engines).

The vehicle maintenance schedule calls for timing belt replacement at a specific mileage, so find out what that mileage is if your engine has a timing belt, and realize that you need to be the one to decide when the timing belt is replaced rather than letting the timing belt decide. The timing belt doesn’t generally choose a convenient moment to fail.

The vehicle maintenance schedule calls for timing belt replacement at a specific mileage, so find out what that mileage is if your engine has a timing belt, and realize that you need to be the one to decide when the timing belt is replaced rather than letting the timing belt decide.

–Richard McCuistian, ASE Certified Master Automobile Technician

Engines with timing belts may or may not be damaged if the timing belt strips its teeth. Fords and Toyotas with timing belts don’t usually suffer engine damage when the belt fails, but Mitsubishi and Kia engines typically DO suffer engine damage. Some Kia four cylinders will quite literally destroy themselves if they jump time because they tend to snap the heads off valves. Mitsubishi timing belted engines will usually just bend valves.

One way or another, always follow the OEM recommendations for timing belt replacement. If the OEM calls for 60,000 miles, do it BEFORE that mileage. If it’s 104,000 miles, do it early. It’s the best policy. Whether you do it or hire it done, it needs to be done exactly right – a timing belt that is too loose will cause slapping sounds, and a belt that is too tight can make an odd whirring noise, believe it or not, so the timing belt tension has to be just right.

An In-Depth Look at Valve Timing

Each bank of cylinders on an Internal Combustion Engine (ICE) has a camshaft that has spin in time with the power-producing crankshaft, which is driven by the pistons. The engine is basically a metal machine that breathes in air and fuel, uses it to produce power, and then sends the processed gasses out the tailpipe as CO2 and water vapor, and the valves that are operated by the camshaft must operate in the right sequence and in the right way.

There is always some mechanism connecting the crankshaft to the camshaft. For years there were engines that had the two shafts directly geared to each other, and there were timing marks on the cam and crank gears that had to be properly aligned during engine assembly. On those engines, the cam gear would typically be some kind of composite material to prevent the gears from making noise, which cam-driving gears are prone to do in a big way.

Older V8 and V6 engines (with almost no exceptions) have a single camshaft in the engine block just above the crankshaft. The crankshaft drives the camshaft via gears and a chain.

The crankshaft on those engines is always fitted with a steel gear and keyed to the crankshaft boss to keep it one with the crank, and the camshaft typically has an aluminum gear with a similar arrangement and the camshaft gear teeth is heavily coated in plastic. The diameter of the camshaft gear is twice that of the crankshaft gear because the camshaft only spins at half the speed of the crankshaft by design. This is true even on modern engines.

The timing chain on these older V style engines is of the laminated variety, somewhat prone to stretching, but very quiet in its operation. After about 100,000 miles, those laminated chains tend to develop enough stretch so that they sometimes strip the plastic-coated teeth off the cam gear and jump time.

But even if they don’t jump, they can stretch enough to allow the camshaft to be spinning just a little bit behind the crankshaft, putting the camshaft slightly out of time. This affects valve timing and causes a loss of engine vacuum, as well as, a loss of engine power.,

If the timing chain jumps enough teeth on the older V engines, some of the valves can be opening far enough out of time that they can be bent by rising piston crowns.

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