Do Diesel Cars Have Timing Belts?

Timing belts are used in almost all modern diesel engines used in cars, utes, and vans, and if the belt breaks, the engine will be severely damaged.

Do diesel engines have timing belts or chains?

This is a familiar topic, but one that deserves to be revisited. The drive mechanism that drives the camshaft, which in turn operates the inlet and exhaust valves, is an important component of any automotive engine. Because of the high compression ratio and hence the narrow combustion space in practically all diesel engines, if the timing is off for some reason, the piston can contact any of the valves and inflict very expensive engine damage if a valve is open at the top of the piston’s stroke.

As a result, any such occurrences in the systems that control the valve gear must be avoided, which means that the drive system must never allow this circumstance to occur. However, if a toothed drive belt or a chain breaks, a calamity can and does occur, despite the fact that cam belts have gotten more durable in recent years. As a result, proper cam belt (or timing belt) and timing chain maintenance is critical. In the case of cam belts, this entails replacing the belt at predetermined intervals, which are car type and engine specific rather than engine particular, meaning that a 1.6-litre HDi or 2.0-litre TDI engine may have various replacement intervals in different automobiles. A low mileage car may need to be replaced after five years, even though it has not yet hit its specified mileage of, say, 80,000 miles. Many belt failures are due to belt degeneration, potentially due to oil pollution, or more commonly, failure of the equipment that maintains belt tension, typically a system with tensioning rollers that absorb any stretch that develops over the belt’s lifetime. The bearings in the rollers of the belt tensioning system might fail very frequently, which is why the tensioning unit must be replaced when the belt is replaced. It’s also a good idea to replace the water pump at the same time, as it has a similar lifespan as the cam belt and can cause expensive engine damage if it breaks. It’s something that’s pretty expensive to replace on its own, so doing it while the belt and tensioners are being replaced is a good insurance policy that only costs the parts and a tiny amount of labor.

When it comes to cam belt, tensioner, and water pump replacement, it’s always a good idea to shop about, and you should always be aware of your car’s cam belt replacement mileage or time. Moving the car on a few thousand miles before it’s due is sometimes a good idea, especially if you’re thinking about changing your car anyhow, because the cost is normally between £400 and £700, including labor. If you want to send your car to an independent garage, Mr Clutch, a nationwide specialized organization, is experienced and offers cheap belt replacement pricing. Cam belt replacement is not a job we recommend performing yourself unless you are a very skilled technician, as the consequences of getting it wrong (such as the belt being installed a tooth or two off the correct timing) are severe.

Finally, a word about timing chains. We don’t have enough to list all of the diesel engines that use timing chains rather than belts (in a nutshell, all BMW, Mercedes-Benz, Honda, Kia, Hyundai, Subaru, Fiat/Vauxhall 1.3, and others), but keeping the chains in excellent shape is largely dependent on regular oil changes. Regular oil and filter changes can cause early chain wear, and the potential harm from failure, as well as the high expenses of replacement, should not be overlooked. A rough idle and a regular clicking or rattling noise can just alert you of timing chain difficulties if you remove your bonnet occasionally (as you should!) and listen to your engine tick over, but a cam belt on its last legs will give you no such helpful warning.

When should a diesel timing belt be changed?

It’s critical to change your timing belt at the mileage intervals recommended by your vehicle’s manufacturer. Every manufacturer is different, but it should be replaced every 60,000–100,000 miles on average. The recommended maintenance period for your vehicle can be found in the owner’s manual.

Because the timing belt is comprised of rubber, it will ultimately deteriorate and break. When it fails, the engine will either stop operating or the components will be out of sync, causing the engine to malfunction.

You risk total engine failure, damaged or bent valves, cylinder head or camshaft damage, and piston and cylinder wall damage if you don’t change the timing belt at the specified interval. It’s not the kind of circumstance where you can safely say, “If it ain’t broke, don’t fix it.” To save thousands of dollars on engine repairs or replacement, replace the timing belt according to the manufacturer’s maintenance schedule.

Signs That It’s Time to Replace the Timing Belt

Before a timing belt breaks, there are often no warning indicators. However, the following are some possible symptoms that it’s time to replace your belt:

We recommend replacing the water pump while your car is being serviced. When the timing belt is removed, the water pump usually has a comparable lifespan and is straightforward to reach. You will save money on labor expenditures this way.

Do diesels use timing belts?

It’s difficult to tell when something has to be replaced unless you’re a mechanic. One of the most prevalent problems in a diesel engine is the timing belt. It’s simple to tell whether you need a timing belt change if you know what to look for.

Why do diesel engines last so long?

A gas engine would have reached the end of its life 20 years ago at about 100,000 miles, but today’s engines are constantly making another trip around the odometer. However, while gasoline engines can now reach 200,000 miles and beyond, diesel engines can also reach 500,000 miles and beyond. The following are three reasons why diesel engines survive longer than gasoline engines:


We’ve all learned the hard way that larger isn’t necessarily better. Diesel engines, on the other hand, are designed to endure longer than their gasoline equivalents. Compression ratios and cylinder pressures are higher in diesel engines than in gasoline engines. Diesel engines are designed with these factors in mind. Their crankshaft and camshaft are larger, necessitating larger bearings and stronger main and rod bolts. Increased clearance from larger crankshafts and camshafts provides for greater oil flow. Better engine lubrication means reduced engine wear, which extends the engine’s life.

Other significant design features of the diesel engine contribute to its durability, including:

  • Most diesel engines feature a gear-driven construction, which means you won’t have to worry about timing belt issues. This also saves money on costly maintenance because the timing belt does not need to be replaced.
  • Piston cooling jet – Piston cooling jets spray engine oil on the bottom of your pistons in diesel engines. This engine oil spray protects pistons from premature wear by keeping them properly lubricated, which lowers friction and keeps them cool.
  • There are no spark plugs in diesel engines, so the gasoline burns more slowly. Because of the slower burn, there is less stress and more torque, which is essential for diesel engine efficiency.

Diesel Fuel

The fuel that diesel engines burn is another reason they survive longer than gasoline engines. Diesel fuel is a form of distillate fuel made primarily from crude oil, which allows diesel engines to wear their cylinders out more slowly than gasoline engines. This adds diesel fuel lubricating qualities, extending the engine’s total lifespan. On the contrary, gasoline is mostly composed of aromatic hydrocarbons, which function similarly to harsh and corrosive solvents. This lack of lubricity causes your engine’s components to wear out prematurely. Diesel engines have lower exhaust gas temperatures (EGTs), which contributes to their increased lifetime. Despite the fact that diesel fuel has 139,000 British thermal units (BTUs) compared to 115,000 BTUs for gasoline, the principles of thermodynamics dictate that the higher compression ratio diesel engine’s expansion rate actually cools the exhaust gases faster. The first flame front is cooler due to the lower auto-ignition temperature of roughly 410°F for diesel fuel compared to 495°F for gasoline. Diesel engines also have a substantially lower air-to-fuel ratio, ranging from 25:1 to 70:1, compared to 12:1 to 16:1 for gasoline engines. EGTs are cooled by a lower air-to-fuel ratio. In addition, gasoline burns more faster than diesel fuel. Because of the slower laminar speed of the flame during combustion in diesel engines, there is less shock to the rotating assembly, which adds to their durability.

Lower RPMs

The third factor that determines how long a diesel engine lasts is its operating efficiency. In comparison to a gas engine, diesel engines have lower revolutions per minute (RPMs) and produce more torque. The ability to create the same power at lower revolutions implies less wear on your pistons, rings, cylinder walls, bearings, valves, and guides, extending the life of your engine. When diesel engines are not in use for long periods of time, they are usually left running. The regular cycling of turning the engine on and off saves wear compared to a gasoline engine since a major percentage of wear occurs at starting. It also decreases heat cycles and maintains stable operational temperatures.

Expert Spotlight:

PSP Diesel in South Houston, TX, is known for their 6.0L Ford Powerstroke builds, and Stephen Peters has this to say about why diesel engines survive longer:

“Diesel users often use their engines for far more than what they were designed for. In contrast to the conventional start/stop patterns of a gasoline engine, this is typically done to generate maximum torque and run for longer periods of time during the day. They aren’t exposed to abrupt starts and stops. One of the most abrasive actions on a motor is starting it. While idling your engine is not good for its longevity, that is exactly what the majority of these trucks are doing. They run long hours and are worked very hard because they are started at the beginning of the day and shut off at the end, but that is their job.”

Peters continues, “Diesel engines are simply intended to be more durable. For example, the blocks are larger, the walls are thicker, and the pistons are larger. And, even with the extra weight, let alone the tight tolerances in the rings to avoid blow-by, the design was created with lubrication in mind, reducing friction and damage to the rubbing parts.”

What cars dont have timing belts?

The timing chain is found in the engine of a car and synchronizes the various components of the engine so that they can function together. It’s constructed of metal links like a chain and conveys the crankshaft’s movements to the camshaft. This enables it to grasp the various gears and wheels.

Depending on the model of your car, the timing chain can be single, double, or triple. The presence of a hydraulic tensioner keeps it tight.

Timing chain vs timing belt

The timing chain, as previously stated, is utilized to synchronize the movement of certain engine elements. This reminds me of the timing belt! On some car models, the timing belt can drive the water pump, which may be the only difference. Aside from that, they’re essentially responsible for synchronizing the crankshaft, camshaft, pistons, and valves.

Timing belt or chain: Which is better?

  • The timing chain’s greatest strength is its longevity. Because of its high strength, it should not need to be replaced in most cases, and it should survive the whole life of the vehicle.
  • With the exception of a check after 125,000 miles, a timing chain does not require any maintenance.
  • The metal in the timing chain, unlike the rubber in the timing belt, is resistant to temperature variations.
  • Because a timing chain is heavier than a belt, it consumes more gasoline (and hence produces more pollution), lowering your fuel efficiency in the long term. Its weight also has an impact on engine output.
  • Because the timing chain is made up of metal links, it must be maintained with engine oil on a regular basis.

What cars have timing chains instead of belts?

A timing chain is becoming more common in automobiles. Timing chains are standard on Mercedes and BMW vehicles.

The following is a partial list of vehicles that can be equipped with a timing chain:

You may check whether your automobile has a timing belt or chain by asking your mechanic, consulting your owner’s manual, or visually inspecting it by removing a cover at the engine’s end. The timing chain is immediately identifiable by its metal links when the cover is removed with the proper tool, whereas the belt is comprised of rubber and is much more flexible.

If you’re still not sure, ask your mechanic: “How do I know if my automobile has a timing belt or a timing chain?”

In most cases, you won’t need to replace your car’s timing chain. Poor lubrication has most likely destroyed a chain that has to be replaced.

If the timing chain is damaged, it is critical that you get a reputable technician to repair it. In rare cases, the mechanic will have to completely remove the engine to get to the timing chain. If the timing chain breaks, it may cause damage to other engine components such as the valves, making the repair more difficult and costly.

Does timing belt give warning?

Because the timing belt might fail without causing any symptoms, if you’re within the mileage range, you should have it replaced. However, your automobile may occasionally give you a heads-up that the belt is worn out. If you see any of the following, you should take your car to a qualified auto repair shop:

How much does it cost to replace timing belt?

The cost of replacing a timing belt is determined by the number of labor hours required to complete the task. After all, some cars make it much more difficult to access components such as the timing belt.

Because economical cars with small engines are easier to deconstruct, labor should be less expensive. However, if you drive an SUV or a truck, you will spend more because the engines are larger.

The cost of replacing a timing belt might range from $300 to $500 in total (more for larger cars, trucks, and SUVs). The timing belt itself is usually less than $50, but labor accounts for the majority of the expense of a timing belt replacement.

The labor will cost anything between $250 and $450 or more. Taxes and fees will almost certainly be added to these rates.

NOTE: Because the water pump is in the same area, it’s often advisable to replace it at the same time. A new water pump may cost a little extra, but you’ll save a lot of money on labor charges if you do it now rather than later.

What happens if timing belt breaks while driving?

In an interference engine, if the timing belt breaks while driving, the camshaft stops moving, leaving some of the engine valves open. This could cause serious engine damage, such as broken or bent valves, damaged pistons, and possibly a wrecked cylinder head and block.