What parts require replacement and why

After a new vehicle is conceived there are a host of automotive engineers that work on the aesthetics, chassis, and engine components prior to putting the vehicle on the production line, and then rolling them into car showrooms. They put individual components through rigorous tests. They also test that all the parts and fluids work well together, ensuring they create a reliable, efficient, and safe machine.

But as well as all these things are tested, they operate under stress, and have a finite life. Hence your car needs to be regularly serviced.

When it comes to car servicing, items are serviced because they:

  • Conform to the list of recommended scheduled service tasks at recommended intervals by the manufacturer to prevent possible component failure.
  • Serviceable items like fluids and parts are inspected or replaced to ensure that your vehicle runs at its best and meets any warranty requirements, based on test results for efficiency of the product.
  • Parts are replaced due to wear and tear — cars, parts, driving conditions, and servicing history vary.

Your car is operating in the real world, rather than the conditions the manufacturers test in.

In such cases components might fail quicker than manufacturer recommendations.

So, what are you being charged for as part of a car service, and why does it need to be done?

Air Filter

The air filter does just that — it filters the air that combines with fuel to create a combustible mixture, and the filter removes any foreign bodies from entering your engine.

All these foreign bodies end up in your air filter, so it will eventually get dirty, and clog up.

If you continue to drive with a dirty/clogged up air filter you run the risk of reducing the air flow into your engine, which could change the air fuel mixture within the engine combustion chamber.

This could create engine wear and contamination and effect overall vehicle performance as the air fuel mixture will not be optimal for your engine.

A majority of vehicles generally us a flat panel filter construction consisting of folded paper or foam, situated within the air intake box at the front of your engine bay.

However, there are many different types of filters on the market to suit specific vehicles and requirements.


As you can imagine an internal combustion engine will get hot, due to the power created by the engine.

But there is a limit on how hot an engine can run, and cooling is necessary to have the engine run optimally and safely.

The engine temperature is regulated by a system using air to cool water/coolant.

Without this system, your engine will overheat, lose performance, create excessive wear, or, at worst, the engine will seize, and you’re up for a new engine.

Modern cars have moved away from using water alone to cool the engine, and instead use a mix of water and coolant additive, as it provides higher engine temperature tolerance, and anti-corrosion properties.

The coolant is fed into your radiator, which is commonly situated at the front of your engine bay, in a position where air can flow through it.

From there, once your engine has reached a certain temperature the coolant will flow through a thermostat, and then through chambers within the radiator, making its way back to the engine.

The type and mixture of coolant used will vary depending on your vehicle and engine cooling needs.

The life of the coolant will also vary depending on the application. All of this is covered in your vehicle’s handbook.

Cabin Filter

The cabin/pollen filter performs the function of filtering the air that enters the cabin of your vehicle.

It is usually situated under the dash, behind glove box or possibly in the engine bay.

Its job is to remove contaminants from entering the cabin, such as mould, environmental pollutants, dust particles, airborne material, and pollen, which can make the journey more pleasant especially if you suffer from respiratory problems or allergies.

Over time the cabin filter will get dirty and clogged, and requires replacement at certain intervals.

Brake Fluid Flush

Your brakes work by a hydraulic system of pipes and cylinders filled with brake fluid. When you push the brake pedal down hydraulic pressure goes to the calipers in turn applying pressure to the rotor stopping the car.

If the brake fluid contains sediment, appears cloudy or discoloured, then it is time to flush your brake fluid. If your brake fluid levels drop it could indicate an issue with your brakes, such as leakage, brake pad wear.

Brake fluid needs to be changed at certain intervals due to moisture contamination, that will result in spongy brakes, corrosion,

This is preventative maintenance – it is crucial in making sure your brakes work at all times.

Engine Oil and Filter

Different makes and models of vehicles will have various service schedule intervals.

When it comes to changing the oil and oil filter this will occur usually every service, however in some cases maybe every second service.

It will generally be done between every 10,000 to 20,000 km, however if you have an older engine you may want to check your oil level and condition more frequently.

The engine oil and the type of oil used is vital. Your engine has many moving parts and these parts create friction and heat when they move.

The oil used will absorb heat and lubricate the engine, without it your engine would wear prematurely, and possibly seize.

If your oil gets dirty the oil filter will eventually clog up, and not perform properly, allowing dirty oil to circulate through the engine, and not lubricating and cool the engine efficiently.

Fuel Filter

The fuel filter is usually a paper cartridge, removing large foreign particles such as rust and dirt from your fuel system.

If you don’t replace the fuel filter at regular intervals it will eventually clog, and restrict fuel flow, resulting in a drop-in performance.

On some diesel engines water may collect at the base of the filter, which needs to be emptied at certain levels.

If not maintained, and water gets mixed in with the fuel this will cause corrosion and wear on moving parts.

The fuel filter is situated along the fuel lines, either within the engine bay, near the fuel tank or inside the fuel tank.

If your fuel filter is an in-tank filter this can take extra time to replace as the mechanic will need to access the top of the fuel tank, this may involve removing your rear passenger seats to access the tank through the floor of your vehicle.

Some mechanics / vehicle manufacturers will suggest replacing your fuel filter every 12 months, however every vehicle, and the type of filter fitted are different, so check your log book for replacement intervals.

Timing Belt/Chain

The timing belt or chain synchronises the crankshaft rotation with the camshaft (The difference between timing belt and timing chain).

It is either a toothed belt or a roller chain. A chain is more durable, and in recent times manufacturers are starting to revert to using chains, after belts had been the dominant choice for the past couple of decades.

Every engine is different and the service interval for a timing belt can differ from every 40,000 to 150,000 km, while a timing chain can be up to every 200,000 km.

If you don’t replace the timing belt/chain when required you could do extensive damage to your engine.

Over time a belt / chain may stretch, wear or break. If this happens it can do a lot of damage to your engine.

This service can be expensive and can take a lengthy period of time to do. Generally, your vehicle will be off the road for a least a day while this is being done, but well worth the peace of mind.

Spark Plugs/Glow Plugs

As an internal combustion engine requires combustion of fuel to operate, there is a need to create a spark to ignite the air/fuel mixture.

In petrol engines this is done via the spark plugs; in diesel engines glow plugs are used, kicking in and helping when the engine is running cold.

A spark plug consists of a shell, insulator and conductor, situated within a threaded hole through the wall of the combustion chamber.

Spark plugs come in all shapes and sizes and vary due to different requirements for each engine type.

At specific times determined by the ignition system a current is directed through to each spark plug.

When the current jumps across from the electrode it creates a spark, igniting the compressed air / fuel mixture within the combustion chamber, creating the energy for the engine to operate.

Each type of spark plug has a different life expectancy depending on brand, design, construction material, application, and most importantly the environment it operates in.

If you don’t change your spark plugs when advised you run the risk of engine damage, difficulty starting, and misfiring. There is often one spark plug per cylinder, however some vehicles have multiple plugs per cylinder.

A glow plug is a heating devise used to assist a diesel engine when it is cold. Diesel engines will usually self-combust under high pressure; however, it may need help to reach temperature on cold start. The end of the glow plug heats up and glows, when the fuel hits the tip of the glow plug it will ignite the air fuel mixture.

Valve Clearance

At certain service intervals a mechanic may need to check and or adjust your valve clearance. This is the gap between the top of the valve stem and the valve gear.

This inspection can also be referred to as checking or adjusting the tappets.

In some circumstances if the valve clearance is excessive then you may hear a rattling noise from the engine.

It’s important to note that modern engines — and we’re talking since the late 1980s — mostly have self-adjusting systems.

If you do have an older car, then it is a good idea to get these checked at the specified intervals.

Again, if your car is on the old side, some mechanics prefer to check the valve clearance when your engine is cold. So be prepared as the mechanic may need to work on this when the engine is cold.

Power Steering Fluid

Power steering allows you to easily turn the heavy wheels of your vehicle at low speeds. An essential part of your power steering is the power steering fluid.

This fluid should be checked regularly and replaced when required.

Your power steering fluid levels should not vary greatly over time, so if you notice the levels dropping then you should get it checked straight away.

The power steering reservoir is situated within your engine bay and the cap will have a picture of the steering wheel on it.

Over time your power steering fluid will pick up debris and dirt, and should be flushed at select intervals.

You can experience issues with the power steering system if fluid is not flushed when required. If you hear a strange noise when turning then you should have it checked out.

Drive Belt/Fan Belt/Serpentine Belt

These belts winds their way across the front of your engine — it can be a single belt, or multiple.

It powers your air conditioner, power steering, alternator, and possibly your water pump. With all these components relying on this belt it is essential that it is in good working order and tensioned correctly.

There are generally two types of drive belts — V-type and serpentine. The groove construction of the belt determines the difference between the two types. To eliminate slipping the grooves increase the surface area to hold the belt in place.

These belts should be checked at every service and replaced if there are any signs of wear or damage.

The tension of these belts should also be checked to make sure they are operating under correct conditions. If you experience a squealing noise on start up or acceleration this could be because your drive belt is slipping.

Clutch Fluid

Clutch fluid is actually brake fluid that is kept within the clutch master cylinder.

The clutch master cylinder moves fluid into the slave cylinder thus engaging the clutch when you depress the clutch pedal, ensuring you’re able to change gears.

The clutch fluid reservoir in most cars is situated at the rear of the engine bay, next to the brake master cylinder.

The brake fluid is an important part of the clutch operation, and it’s important that it is checked and replaced when required as part of service schedule.

Dirty and contaminated brake fluid can cause damage to your master cylinder and slave cylinder. If your clutch master cylinder develops a leak you more than likely won’t be able to change gears.