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What is classed as a small engine? I would suggest that it is any internal combustion engine powered by hydrocarbon fuel of a size comparable or smaller than a car. By hydrocarbon I mean diesel fuel oil or petrol (gasoline). In this article we will confine ourselves to the gasoline engine.
We use small internal combustion (IC) engines for powering almost everything in our life.
This list is not exhaustive and we expect you can think of some applications of the IC engine that we have missed. It doesn’t really matter how many more we add to the list, the point is that we use IC engines probably every day. And some days they just won’t work properly! Why is that? What do we do?
The small IC engine is really made up of many individual systems that are designed to work together. If one of those separate systems stops working or decides to work less efficiently than it is meant to, then all the other systems suffer as well. If you are going to use an IC engine then you should know how they work, how to provide basic maintenance and how to repair it or find someone to do the repairs when it goes wrong.
Every IC gasoline engine needs six systems working together to work properly.
The fuel system provides the raw material to burn which produces the energy to do work. In the case of the fuel, we require liquid gasoline (or petrol in UK) which is dispersed as a spray and mixed with the oxygen in the air. The larger gasoline engines found in cars are usually four stroke engines while the smaller engines such as motorbikes, generators and the others are usually two stroke engines. To explain the difference between four and two stroke is outside the scope of this article so I will leave it up to you to find out yourself but basically four stroke engines use an air-fuel mixture while two stroke engines use a fuel-air-oil mixture. The added oil is to lubricate the internal components. The fuel is supplied to the engine from a fuel tank. The fuel is pumped from the tank along the fuel line to the carburator, where it is turned into a spray and is mixed with air which has been passed through a filter to remove dust and grit. The carburator ensures that the correct amount of air is added to provide the optimum fuel for the engine. Once you have the fuel in the correct air ratio all that is required is a spark to ignite the mixture.
The ignition is produced by a high voltage spark produced by the points, coil and the battery. The points are basically an on-off switch operated by a rotating cam. In more modern cars the points have been replaced with solid state ignitions. The coil changes the low voltage 12V from the battery into a high voltage 30 000V needed by the spark plug. The spark plug screws into the top of the engine cylinder. It is an electrode with a small gap across which the spark must jump. If the engine has more than one spark plug and cylinder, the system needs a distributor to divert the electricity to the appropriate spark plug so the correct piston moves in its proper sequence.
Combustion. This system is where the fuel-air mix undergoes a controlled explosion inside the combustion chamber. The expanding gases from the explosion push the piston, which rotates the crankshaft. In the combustion chamber there are inlet and outlet valves allowing the exhaust gases to exit and the new fuel mix to enter.
Exhaust. The exhaust gases exit the combustion chamber and travel along the exhaust pipe to the silencer (muffler in USA) where chemical reactions take place to remove as many toxic gases and heavy metals as possible before discharging to the atmosphere.
Cooling and lubrication. The combustion and friction produces unwanted heat which has to be removed before damage occurs to the engine’s components. As a general rule small IC engines such as motorcycle and smaller have heat transfer fins which are cooled by moving air whereas larger engines are cooled by circulating water. In order to reduce the friction between moving parts the engine is equipped with steel bearings and uses lubricating oils and grease. In two stroke engines the oil is added to the moving parts by adding the oil to the fuel. The circulating oil passes through an oil filter that removes any small particles of metal that may find their way into the oil.
To keep all these different systems working at their optimum, it is wise to give your IC engine a periodic service. You can either do this yourself if you have the knowledge or employ someone else to do the job for you.
Preferably the answer to this is NEVER! But don’t be afraid to buy a new one if the repair costs are higher than the cost of buying a new machine.
IC engines are expensive to buy and for the sake of a little time and relatively small amount of money, you can keep your engine working properly indefinitely.
The engine should be serviced regularly and this has many advantages compared to waiting until the engine breaks. By working out a schedule of when your engine should be serviced you will always be reassured that the engine will be ready to work properly at a moment’s notice. By doing a few related jobs at the same time (even if they haven’t worn out yet) you will only have to dismantle the component only once rather than many times thus saving time. By doing a regular service it is possible to check the entire engine for wear and fix problems before they become expensive.
Knowing how to is as important as knowing when to service an engine. Even if you are passing the work on to someone else, you will still need to know the approximate scope of the job you are asking them to do. This will be useful to help you know if the tradesman is trying to con you into paying for more work than he has done. Being so suspicious of people who do work for you is regrettable but unless they are either a main dealer or someone you know personally it is always worth being suspicious.
So let’s assume you are unable to do the servicing or repair on your car or motorbike (we will talk a little about smaller engines later). Who do you ask to do the work for you?
Main dealers are usually garages who specialize in selling and repairing a specific brand of car or motorbike. They are usually large businesses and have good links with the manufacturer. They have well trained and knowledgeable employees doing the work and have special tools that may be required to do the work. Their customer service is usually very good and you can usually rely on their work to be first class. They will be able to provide an official stamp on the vehicle service book to prove the regular servicing has been done. A big disadvantage when using main dealers is that because they have large premises, support staff and invest in training, they are always the most expensive option.
Basically, a motoring organisation is a business, usually in the form of a club, to which the motorist pays a subscription in exchange for mechanical help on the roadside or providing transport for you, your passengers and your vehicle to your home in the event of a breakdown. Very useful if you intend to travel a lot in your car and need help in an emergency. The downside of using these organisations is that if the repair cannot be fixed on the side of the road, you will have your vehicle towed to the nearest repair garage. This may not be very convenient if you find yourself stranded in the middle of nowhere. The motoring organisations and vehicle insurance companies realise this and as an added extra on your policy (additional payment) you can be supplied with a rental car to complete your journey. The garage you have been towed to also may take advantage of the fact that your work is a necessity and try to overcharge or charge you for additional work. Motoring organisations are useful in an emergency but should not be relied on for general repairs and maintenance.
A good and reliable local repair garage is worth its weight in gold if you can find one. Usually they are well known in your area and can be recommended by friends and colleagues. If they are local to you then you will find that their work is usually very good and reasonably priced. They rely on local work so will always try to uphold their local reputation. Over the years they will get to know you and your car and will be very knowledgeable about the character and idiosyncrasies of your particular vehicle. They will be able to provide an official stamp on the vehicle service record to prove the required work has been done.
There is always a guy who lives in your neighbourhood who loves to tinker with cars and engines and for a small price will look after yours for you. Usually, this guy is ok to use for small maintenance jobs like changing the oil or changing the brake shoes, but because he is doing the work in his spare time, you might find that a small job takes a long time, very inconvenient! You will also find that you will not have any warrantee or guarantee on his work. This way of having your car repaired is probably the cheapest but will have the most risk. He will not be able to provide an official stamp on the service documents to prove the work has been done.
To do any work on your own vehicle you will require somewhere to work, the correct tools, suitable knowledge and the available time. If you have all these then to do the work yourself will be the cheapest option. You will not be able to provide an official stamp on the service documents but you will have the satisfaction and certainty of knowing that the work has been done according to the book. The trouble with this option is that not many people possess the time or the aptitude to do their own car and engine repair work.
To be honest there is not a lot that can go wrong with a small engine in tools like mowers or chainsaws, or in toys like model aircraft. Having said that we would not recommend that you do your own repairs unless you have the required knowledge and a workshop where you can take the engine apart. Small parts are easily lost if you are trying to repair an engine on the garden path and oily bits and pieces are not a good idea if you are working in the kitchen. Most towns will have a place where you can take mowers, chainsaws, generators and similar tools for repair. Because the engines are so simple, they usually will not cost a lot to have the work done and you have the satisfaction of knowing that you have a place to return your engine if something goes wrong again.
Anyone who works on vehicles that carry people should be qualified to do so. Each time you get into your vehicle and start up the engine, you are trusting that the person who last repaired the car knew what they were doing. Basically, your wellbeing is in their hands. If you think about it like that, then I think you will agree that you want someone who is qualified either by an apprenticeship or some other recognised training course. Even if the person who does the mechanical repairs is qualified, you also have the person who is responsible for the electrical system. How many times have you either seen or heard of a vehicle fire caused by faulty wiring? How about something as simple as tyres. Are they at the correct air pressure? Have they enough tread? Is the tyre so old that the rubber has perished and will split when you are driving at speed? You are trusting that the person who is responsible for all these things is competent and able to do the job properly.
In the UK the foremost qualification is the City & Guilds qualification in Automotive Maintenance & Repair. You can take this qualification as part of an apprenticeship or simply as learning ‘on-the-job’. There are certificates and diplomas for courses designed to teach you the basics and intermediate levels and even higher levels to help you in a role involving supervision and training.
In the USA the requirement is to have a postsecondary award such as an associate’s degree or a certificate in automotive technology. Most high schools offer the required training programs which would be combined with a work placement at a car manufacturer or repair garage. Employers prefer their employees to be certified with the National Institute for Automotive Service Excellence (ASE). This certification requires coursework, examination and experience.
Recommendation. Ask around among friends and family to see who would recommend their local mechanic. Look on social media for ideas. Look out for owners of the same type of car as yours and ask them who looks after their car.
Ok, you now have a shortlist of a few likely local home engine repair contenders. Get in touch with, or look on the website of a respected motoring association in your country. They will have a list of garages and repair shops who abide by their requirements. Usually the garages will offer guarantees, warranties, and have to pass an annual inspection. There are various independent websites dedicated to providing the consumer with information about local car repair centres. Have a look and see what kinds of reviews have been given to those on your list.
Modern cars are moving more and more towards being a computer on wheels. You will have to deal with someone who has the appropriate training, qualifications and memberships to prove they are able to deal with the modern auto technology. City & Guilds and ASE qualifications are for the mechanics not for the establishments so if the technicians who fix your car have these qualifications you will be certain that they know what they are doing. These certificates won’t tell you if they are honest only if they can do the job.
repair centre belongs to the voluntary code of conduct ‘Motor Codes’ they will:
Remember when you ask for an estimate to do a job on your car that you are not only paying for parts and labour, you are also paying for the mechanic’s technical expertise, experience and professionalism. However, remember that if he is more expensive doesn’t mean he is better. Also remember that a bargain isn’t always a bargain.
As said earlier repairs done by a main dealer are usually more expensive than an independent’s work. If you have a car that is still under warranty for parts and labour then it makes sense to continue taking it to the dealer. If you decide to have it done elsewhere always find out if any work done will affect your existing warranties.
A good professional handyman will have references from satisfied customers or will be happy to provide you with a list of them so you can contact them yourself.
Get the mechanic to tell you in detail what is wrong with your car. Ask them for a written quotation. You may not know what he is talking about but you could show the quote to someone who does.
f the technician won’t answer your questions in words you can understand or tries to confuse you or won’t give a definite price range, you can always go to the next guy.
Have a look around the workshop. Is the place full of smiling faces from customers and employees? Notice how customers leave the premises after collecting their car. Are they happy and satisfied? The standard of tidiness and cleanliness in the workshop and office area can tell you a lot about the type of business you are dealing with. What type of cars are being repaired? Are they old rust heaps or vehicles that have been looked after? Just keeping your eyes and ears open will tell you a lot about whether to use the establishment.
Modern cars are computers on wheels. Make sure the mechanic has the high-tech tools as well as the traditional wrenches. Ask to see them and have their operation explained to you.
Before you hand over your precious car, ask about the warranty given on the parts and labour. Make sure you know what is covered, what are the limitations? How long do they last? And get them in writing. See if the establishment uses a national warranty programme in case you need a repair while away from home.
You have to plan this one in advance but take your car to a repair garage, knowing there is nothing wrong with your vehicle. See if the mechanic compiles a list of repairs that have to be done immediately. If you can’t manage that one then take your car for a simple maintenance task, like an oil change. See if you are satisfied with the price, professionalism and workmanship.
There is nothing wrong in asking someone else for a second opinion if you are not happy with a price or a diagnosis. Don’t accept a ‘hard sell’. Don’t be pressured into making a decision. That is the main reason to find a repair centre before you have a major break down with your car. If you are presented with a list of unexpected jobs from the mechanic, don’t feel obligated to have them done. Get a second opinion first.
Believe it or not, most car repair mechanics and technicians will not try to rip you off. They are mostly honest guys and girls just doing a job they love and wanting to be paid an honest day’s wage for an honest day’s work. There are however some crafty people around who will try to con you. It is therefore a good idea to talk about a few scams that you might come across.
First of all there are the obvious scams of trying to overcharge or trying to make unnecessary repairs (usually expensive ones).
One of the most common scams today is the repair job necessary when the wrong fuel has been put in the tank, either diesel into a petrol engine tank or unleaded into a diesel engine tank. It is quite common for traders to quote high prices to simply drain the fuel tank and flush the fuel system. Quite a lot of vehicles are perfectly safe when the wrong fuel has been added. When diesel is wrongly added to the tank all that is needed is to drain the tank and flush the system. It is more serious when petrol is added to a diesel car. Sometimes this can cost thousands of dollars to make good. It should only cost about $500 to repair a misfuelled petrol car. It can sometimes even be done on the roadside by a breakdown assistance service.
Another scam is to do with warranties. Some main dealer garages con unsuspecting motorists into paying high dealership labour rates by telling them that if they use an independent garage the warranty will be invalid. The problem here is not what establishment they use; it is whether the independent garage uses the correct manufacturer’s recommended part rather than a cheaper alternative. If the cheaper part is used, then the warranty will be invalid if you return to the dealership in future.
Be aware of some garages offering free vehicle health checks. Often some garages will say that a certain part will need to be replaced when there is still a lot of life left in it. Unknowledgeable drivers can end up paying for unnecessary work.
The professionals who abide by the ‘Motor Codes’ which garages and repair shops can sign up to. Motor Codes protects motorists from dishonest mechanics and businesses. It has the approval of the government agencies tasked with looking after consumers’ rights, Office of Fair Trading, Trading Standards, Consumer Direct, DVLA which registers all motor vehicles in UK and VOSA which operates the roadworthiness MOT test.
There are certain jobs which are important to do regularly and if done will prevent the majority of serious problems with your car. The most important of these is the care, changing and refilling of fluids. The fluids we will talk about look after lubrication, cooling, washing and operation of the hydraulic system.
Engine oil should be checked once a month and before a long journey. This fluid lubricates the moving parts of the engine. It reduces friction within the engine and so helps to reduce wear and the temperature of the engine components. Oil should be changed about every 5000 miles.
Transmission fluid (or gear oil) needs to be changed every 30 000 to 60 000 miles. This fluid lubricates the gearing mechanism ensuring the power is transferred from the engine to the drive system. Changing this fluid is not easily done by the average person and should be done by a qualified auto mechanic.
Coolant. This should be checked weekly and before a long journey. This is easily done by the motorist and should be a mix of water and antifreeze. Coolant runs around pipes and conduits encasing the engine removing heat from the engine and depositing it in the radiator where the heat is dissipated by airflow when the vehicle is moving. If the vehicle is stationary the airflow is provided by a fan which turns itself on when the coolant reaches a certain temperature. In emergencies water can be used without the coolant concentrate but remember that shop bought antifreeze contains additives to prevent the build-up of rust inside the car radiator so it should be added as soon as is convenient.
Windscreen washer fluid. Although this does not affect the operation of the engine, it allows you to clean dirt from the windscreen and together with the wipers allow a safe driving experience. There is a translucent reservoir in the engine compartment that must be kept full with water. You can buy various detergent additives to combine with the water or simply add a squirt of dishwashing detergent to the reservoir to help remove the road grease from the glass.
Brake fluid. Once again this does not affect the running of the engine but provides a hydraulic medium to safely operate the brakes by transferring the movement of the brake pedal to the brake pads or shoes within the wheel hubs. The fluid level in the brake fluid reservoir must be checked regularly and topped up if necessary. In normal operation this fluid should not need to be topped up very much. If the level drops considerably then the brake system has a leak and it should be checked by a professional. Change the brake fluid every 45 000 miles.
Clutch fluid. Another hydraulic system used in manually geared vehicles to disconnect the engine from the gears. This fluid transfers the movement of a foot pedal to the clutch plate. The fluid level should be regularly checked and topped up if necessary. If there is a large drop in the level then suspect a leak in the system and get it fixed.
Power steering fluid. You will find that more modern and larger cars have power steering. It is designed to assist the driver in operating the steering mechanism. The fluid level should be checked and any major leaks found and fixed. How often the fluid needs to be changed depends on the type and make of car and users should follow the instruction found in the manufacturer’s user guide.
The tools needed to do the tasks in repair and maintenance of your engine are as follows.
These tools will do for most tasks but some manufacturers require special tools to do jobs which they consider should be done by a professional.
Not all sizes of wrench will be needed but it is impossible to say which ones are necessary until you read the user manual.
If you do not have all these tools, they can all be bought from hardware stores or tool shops. Or try your local hire shop.
The most important tools needed to work on an engine are the user manual and your own self confidence. Most jobs are not that difficult as long as you can follow simple instructions.
If you have the time, resources and the inclination to start a new hobby then there is no reason why you cannot do most jobs on your vehicle engine. However if you are like the majority of car owners, and do not have the time, then there is no reason why you cannot use the services of a qualified auto mechanic or technician. The main advantage of using a professional is that you will always have the reassurance of knowing that the work is guaranteed and there is a warranty on all replacement parts. If you insist on doing the work yourself then you will only have to pay for purchase of spare parts.
The costs of repair and maintenance of a vehicle engine vary with the age, how many miles driven and make of car. The cheaper car makes tend to have lower maintenance costs while the high performance luxury cars cost more to maintain. The vehicle itself has many items to check, maintain and replace but the scope of this article is the engine itself so costings will reflect this.
|Task (Parts only)||Price range||average|
|Oil change||$25 to $50||$46|
|Oil filter change||$10|
|Air filter change||Parts $10 to $15|
Labour $18 to $25
|Engine coolant change||$100 to $150||$120|
|Timing belt replacement||Part $25 to $50|
Labour $200 to $900
|Spark plug replacement||Parts $70 to $110|
Labour $115 to $150
The details discussed so far are almost without exception to do with car engines. We will now touch on smaller engines found in motorcycles, tools and toys.
Motor cycle engines are smaller, have less component parts and are easier to work on, both professionally and DIY. Generally all that can go wrong with an average motorcycle engine is limited to air intake, fuel mixture and sparkplug ignition. The components are easier to access and if necessary the bike can be lifted onto a workbench.
In this category we include motor mowers, hedge trimmers, rotavators, chain saws, generators and similar tools. Almost certainly there will be a shop near to where you live where you can buy these sorts of tools. Usually there is also a workshop where you can have the tools serviced, repaired and maintained. Prices vary with make and model of machinery, so it is better to ask for a quotation before having the work done.
If you want to do the work yourself, you will be able to do most, if not all the tasks required to get your equipment in good working order. These engines are easily lifted onto a workbench and are very easily dismantled. You have the added advantage that you will not be using these tools every day so it won’t matter if the engine is dismantled on your bench for a week or two. Probably you will be using them for a week or two once or twice a year so it is possible to work on them at your own pace. Instruction manuals are easily found for your model on the manufacturer’s website.
In this category we will include model aircraft, radio controlled cars, model boats and similar items.
Because of the small scale of these engines, the fuel is usually not gasoline but a fuel called ‘glow fuel’. Glow fuel is a mixture of mainly methanol with additives of nitromethane and two stroke oil. There is no independent lubricating system in these engines so like motor cycles the oil is included with the fuel. Similar to motorcycles the engines are very simple and have few parts needing replacement. Generally model enthusiasts incorporate the building and maintenance of their models into their hobby so working on the engines is not usually a problem. If there is some maintenance work that you would rather not attempt, then the manufacturer or retailer will be able to advise on a reputable repair centre.
Small internal combustion engines all work on a similar system; the controlled burning of a mixture of fuel and air in a chamber. When the burning takes place, gases are produced that expand and drive a piston. The linear motion of the piston is then transferred into a rotary motion suitable for doing work.
Most tasks needed for repair and maintenance are simple and straightforward enough for anyone with some practical knowledge, tools and an instruction manual to complete with little difficulty providing they have time and a place to work.
If the owner of the engine chooses not to do the work personally, there are many professional tradesmen willing to do the work on your vehicle. If the maintenance is needed for a motorcycle, tool or toy, there will be fewer places available to do the work but they will still do a good job.
Before handing over your precious machine, always ensure the technician has the appropriate training, knowledge and tools to do the task. If you ask they will be only too pleased to provide references and certificates for your inspection. Don’t forget to ask for a quotation for the work to be done and find out about any warranties.
It is very important to make sure your vehicle, tool or toy are kept at their optimum efficiency. If you forget to get the service or maintenance done, there may be a very large repair bill waiting when the engine finally stops working.
Last but not least, it is important to realise when to stop having your engine repaired and instead buy a newer model. Usually it is when the repair and maintenance bills arrive more frequently and become higher and higher. When this happens, sell it for spares and buy a new one. Simple!