Nothing lasts forever, especially car parts, but just how long can an automotive component be expected to work efficiently before you should have it replaced? MIKE MONK discusses some of the more common items with the RMI’s Hedley Judd.
Regular servicing of a vehicle is a necessary factor of motoring life, and while we all expect the usual bill for ‘plugs, oil and filters’, it is when other, longer lasting – and generally expensive – items have reached or passed their limit of effectiveness that the motoring budget gets an unwelcome shock. But because they are not routine service items, are generally ‘out of sight’ and can last months, if not years, without requiring replacement, they can be taken for granted. And that is the danger, especially if they are ‘life and death’ items. It is important to realise that anything that can be categorised as a service item implies that it has a calculated life expectancy.
In order to ensure that a vehicle is maintained to the best possible standard at all times, manufacturers set out a time or distance-related service interval based upon a variety of factors relating to all the component parts that make up the vehicle. Apart from the general plugs, oil and filters, these include such items as brake linings and shock absorbers. It is interesting to review these critical parts as an indication of just how much ‘wear and tear’ takes place and, hopefully, raises our appreciation of how much not only these particular parts perform but other significant components too and, consequently, lessen our dismay when they have to be replaced.
“With a conventional four-stroke engine, spark plugs need to fire on every fourth piston stroke, so a four-cylinder engine running at 4 000 r/min means requires that each plug must fire a spark 2 000 times a minute – or 33,3 times a second,” explains aftermarket parts expert Hedley Judd. “Each time a spark occurs a tiny piece of metal is eroded from the plug’s casing, which consequently causes a reduction in efficiency of a spark plug over time. As a result, the stress on the ignition system is increased in order to provide a spark across a larger gap, and the timing of the spark can be slightly off, leading to reduced power and increased fuel consumption.”
When it comes to lubrication, oil is being circulated under high pressure and temperature the entire time an engine is running, and the filter has to remove any impurities at the same pace. If the filter is left to continue forever it will become increasingly clogged and ineffective, therefore must be replaced to ensure the free flow of oil. The same principle applies to the air filter, which captures dust and particles before they can enter the engine, thus preventing excessive wear and tear.
“Both spark plugs and the filtration system should effectively be replaced along with new fluids at the 200 hours of engine operation mark,” says Judd. “Translated into kilometres, if one assumes an average urban/suburban driving cycle at approximately 75 km/h (allowing for 50:50 town vs freeway), then the interval works out at roughly 15 000 km. If the driving cycle is biased towards varies the urban cycle, and thus a far lower average speed, the hours of operation reduce the kilometre interval accordingly.”
Probably one of the biggest component concerns are brakes – one of a vehicle’s critical safety functions. “The lifespan of discs, drum and linings depends heavily on the driver’s driving style, the regular terrain of operation, if the vehicle is used for towing or has been modified. Each of these scenarios can have a negative influence,” Judd continues. “However, the single biggest impact on the lifespan of the brakes is related to the manner in which the system is maintained.”
For peace of mind motoring, to help keep your vehicle’s braking system operating at its optimum level:
• Always replace friction material on both sides of the vehicle, whether front or rear.
• Always either skim (if within tolerance) or replace the discs or drums when worn or scored.
• Always flush and replace the brake fluid at least every 24 months anyway.
Shock absorbers are also safety critical items, as without them working effectively the vehicle’s operation is seriously affected: the braking distance is dramatically increased, directional control, and cornering capability are diminished, and tyre life can be reduced by more than 50%. As Judd explains, “A shock absorber is essentially a piston in a sleeve that goes up and down rapidly according the undulations and bumps in the road, its movement restricted by either hydraulics or gas or both combined. It is this resistance that needs to be maintained for effective operation. A shock absorber could move as much as 2 000 times per kilometre on a tar road, so imagine the movement on a dirt road. As a rule of thumb, based on the volume of oscillations per kilometre, the lifespan of a quality brand shock absorber would not typically exceed the 80 000 km mark.
“Naturally, the progression assumes that the better the quality of the part the better the capability of the part to perform its role in the service interval. In some cases it is expected that a part that costs more should last longer. This is true in some of the wear items in the vehicle parts mix, but is not always the case,” concludes Judd. Check out the component’s warranty/guarantee conditions before buying – and you always try Google…
We have only touched on a few components here, but the principle applies to many more components that make up today’s sophisticated and, in some cases, complex vehicles that form such a key role in day-to-day living.
Hedley Judd has extensive knowledge and experience in the motor industry retail aftermarket trade. He is a director of the Retail Motor Industry organisation (RMI) and three of its associations, the Motor Industry Manufacturers Association (MIMA), the Motor Parts & Equipment Association (MPEA) and the Tyre Dealers & Fitment Centre Association (TDAFA).