MECHANICAL TIPS

The object behind this information briefing is to provide an overview of the workings of both diesel and gasoline internal combustion engines. This is not a technical workshop manual but rather a gathering together of information in simple terms to give the reader a picture in his or her mind of the working theory. This information coupled with some common sense should enable the amateur to fault diagnose, and maybe even get out of a problematic situation in the field.

The need for this knowledge, in view of the widespread use of local drivers, is still of paramount importance. This is due to the low mechanical and practical standards of some of the locally hired drivers I have encountered in the field.

I also have the feeling that if there is a basic understanding of the mechanics involved then there is far less likelihood of having the vehicles abused and so prolong their life in the field.

Disclaimer:-

The information on these pages is offered to assist those of the Humanitarian Aid community working in arduous conditions in the field where due to certain constraints posed by severe climate or rebel activity these tips could prove invaluable. I have worked in the field for many years and as a result have compiled the following list of tips after using them myself. I take no responsibility for any damage caused to either machinery or personnel by the following of these tips, which are laid down in good faith. All Safety guidelines plus the various Aid Agency Guidelines should be followed at all times.


The contents are grouped in the following order :-

Contents

Arrow Overview of the internal combustion engine.

Arrow The workings of gasoline engines.

Arrow The workings of Diesel engines.

Arrow Problem solving.

Arrow Problem solving for gasoline engines.

Arrow Problem solving for diesel engines.

Arrow Useful information.


Overview of the internal combustion engine.

To be able to carry out any form of fault diagnosis, and maybe even an emergency repair, it is of great advantage if you are first acquainted with the general principals of the internal combustion engine. You do not, on the other hand, need to know all of the technical details just to have an overview of the workings in your minds eye.

A few basic principals of the workings of a diesel engine, for example, apply to diesel cars, trucks, generators and large marine engines. Yes they are all the same but they have different components of different sizes and usually placed in slightly different positions. The working principal, though, still remains the same.

To simplify matters we are going to deal with what takes place in just one cylinder of a gasoline engine and one cylinder of diesel engines through their full running cycle. The same principals will apply regardless of how many cylinders are actually used in a particular engine.

Also we are only going to discuss the four-stroke cycle (fully explained in the later text) for diesels and gasoline engines. There is also the two stroke cycle in use, but it is only generally found in use in smaller capacity engines (such as some small generators, chain saws, outboard motors and some small motor cycles).

First of all, and probably most important, what exactly is meant by the term Internal Combustion Engine?

Simply put it means the burning of a flammable substance (fuel) inside the engine, the substance in this case being either Diesel Oil or Gasoline (petrol). This burning of the fuel is where these engines derive their power from and just how it transpires is dealt with in the following sections under the headings Gasoline Engines and Diesel Engines.

Secondly, what exactly is meant by the term FOUR-STROKE cycle ?

To derive it's power from the heat of the burning fuel the four stroke engine (whether diesel or gasoline) has to complete four separate cycles. The completion of four piston cycles takes 2 complete crankshaft revolutions. These cycles are explained in greater detail, (together with the aid of sketches), in the next two sections of this work, but briefly, look below for a brief overview.

Induction

Intake (suction) of air alone (in a diesel engine), or, air and gasoline vapour in a gasoline engine.

Compression

Compressing of the above gases.

This completes the first revolution of the crankshaft.

POWER

Igniting of the compressed gasoline vapour by a spark within a gasoline engine, or, the injection of a diesel mist through an injector, which then self ignites due to the heat, generated by compressing the air. This produces a rapid expansion and therefore power.

EXHAUST

The blowing out of the spent gases. And then the process starts all over. This completes the second revolution of the crankshaft.

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GASOLINE Engines

GASOLINE (also know as petrol, Benzene and Gasolina) evaporates very quickly giving off highly inflammable vapours. With any gasoline spillage be extremely careful of any naked flames or sparks (i.e. from the vehicles electrical system, welding equipment, cigarettes etc).

THE INDUCTION STROKE (first cycle)

The figure to the left is a simplified cut-away drawing of the internals of a single cylinder engine.

The drawing represents the Piston moving down the cylinder.

The piston is attached to the Crankshaft by means of a connecting rod. As the crankshaft rotates the connecting rod draws the piston downwards.

(The crankshaft rotates clockwise in these diagrams)

Gasoline is converted into a fine mist with the outside air inside a carburetor or an injection system (Both types are not shown in the drawing).

The inlet valve is opened and thus allows the entering of the gasoline and air mixture, into the cylinder, in readiness for the next cycle. During this cycle the exhaust valve remains closed.

THE COMPRESSION STROKE (second cycle)

Both the exhaust valve and the inlet valve are now closed.

The crankshaft continues to rotate, with the aid of a flywheel, and this action forces the piston back up the cylinder bore. As a result of both valves being closed the gasoline / air mixture has nowhere to go, so compression now takes place. The ratio of compression is typically in the range of between (7 to 1) to (11 to 1) depending on the engines designed performance.

The "compression ratio" is that of the ratio of the total volume of the cylinder above the piston when it is in it's lowest position to that of the "combustion" or clearance space when it is at its highest position. (In other words, if 10 cm of air in a bicycle pump were compressed into 1 cm then you would have a "compression ratio" of "10 to 1").

This has now completed one revolution of the crankshaft.

THE POWER STROKE (third cycle)

Both the exhaust valve and the inlet valve remain closed.

Just before the piston reaches the top of its stroke a high voltage is created within the "High Tension Coil" and is fed (via the distributor) to the spark plug. This high voltage jumps the gap between the spark plug contacts and ignites the compressed gasoline / air mixture.

This results in a rapid burning (expansion) of the gasses which forces the piston back down the cylinder bore, and in the process turns the crankshaft.

This is Power.....

THE EXHAUST STROKE (forth cycle)

The inlet valve remains closed but the exhaust valve is now opened.

The crankshaft continues to turn, forcing the piston back up the cylinder bore.

Because the exhaust valve is now open the movement of the piston forces the burnt gasses out of the cylinder, through the silencer and out into the atmosphere.

This has now completed the second revolution of the crankshaft. The whole process is now ready to begin again at the induction stroke.


With this short explanation and the aid of these simple sketches I hope you can now grasp some of the important issues taking place here. The sequence (TIMING) of movement of the components is of prime importance. The valves must open and close in the correct order and the spark must arrive at just the right time to ignite the fuel / air mixture. Also the fuel / air mixture from the carburetor must not be too rich (too much fuel) or too weak (too little fuel known as lean).


VALVE TIMING

The valves are opened by the CAMSHAFT. The camshaft is in essence just a bar of metal with projections (CAMS) sticking out along its length. As the camshaft rotates these projections move the valves to an open position.

Valve closure is accomplished by the use of springs. The position of the projections on the Camshaft is set by the manufacturer but the controlling of the rotation is governed by its assembly into the engine. The camshaft rotates at half of the speed of the crankshaft and is driven from the crankshaft via gears, chains or a toothed rubber belt.

On all engines you will find "timing" marks to help you re-align the camshaft on re-assembly (i.e. The installation of a new toothed belt).

If there are no timing marks to be found, then, an approximate timing can be afforded be positioning the first piston at the top (TDC Top Dead Centre) and setting both valves to overlap (exhaust nearly closed and the intake nearly open).

IGNITION TIMING

The spark itself is produced in a transformer coil (high-tension coil). This coil converts the 12 volts from the battery into many thousands of volts and is created at just the right moment by the opening of a "contact breaker" or electronically by the use of magnets and "Hall effect transistors" (electronic ignition).

As you can imagine the spark generation also has to be at the right time. Too late and the ignition is "retarded" causing overheating due to the very small power output. Too early and the engine will probably backfire, (through the carburetor), run very roughly and sound terrible.

This is all controlled by the positioning of the "Distributor". The drive to most contact breaker shafts is also at half of the crankshaft speed. The distributor is employed for "distributing" the high voltage to the correct cylinder's spark plug. You will see a plastic cap with many leads ensuing. One lead you can trace back to the high-tension coil. The total number of the other leads matches that of the number of cylinders in the engine. The high voltage enters the centre of the distributor cap and is fed via the "rotor arm" to one of the other leads that go to the spark plugs in the "cylinder head". These are set to the "Firing Order" of the engine, which is usually embossed somewhere on the intake manifold. The firing order on a four-cylinder engine might be for example --1, 3, 4, 2 --.

So with this information you can replace these leads if they have become inadvertently mixed up. All you need to ascertain is the direction of rotation of the "Rotor Arm" within the distributor by turning the engine over (with the use of the ignition key or by selecting a low gear and pushing the vehicle forward). Then you replace the leads in the order given (i.e. 1, 3, 4, 2) following the direction of rotation you ascertained from above. The number 1 cylinder is usually nearest to the radiator (front of the car).

The first lead you connect is the most critical for getting the whole sequence in the correct order. The rotor arm will be pointing at one of the leads and this lead must go to the cylinder that is under compression at that time. (This is ascertained by observing which cylinder has not got a valve open at that time).

THE CARBURETOR

The carburetor controls the amount of fuel in relation to the amount of air that enters the engine. This is carried out by the deployment of a butterfly valve, which is linked in turn to the throttle pedal in the vehicle.

The ratio of Fuel to Air is determined by the size of the holes in the "JETS" within the carburetor and is set by the engine designers. But other factors do come into play. The "choke" for example restricts the airflow in the carburetor and thus more fuel, in turn, is administered to the engine (necessary to compensate for the condensation of fuel inside a cold engine). Also a blocked air filter will have the same effect of restricting the air and forcing more fuel into the engine causing fuel wastage through inefficiency and poor running of the engine. Blocked "Jets" on the other hand allow less fuel to enter the engine and weaken the mixture giving rise to overheating and also poor running.

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Diesel Engines

Diesel (also know as Gasoleo by the Spanish and Mazout by the French) has an oily texture and a pungent smell. Diesel does not evaporate very quickly and is more difficult to ignite when compared to gasoline. It is also incredibly difficult to remove from clothing so be careful when filling vehicles or bleeding fuel lines.

The main differences from the gasoline engine are :-

  1. The spark plug replaced by an injector nozzle. Which is used for delivering a fine mist of diesel into the cylinder.
  2. Because of the use of an injector, there is no need for a carburetor to supply the fuel in the right form.
  3. Because the fuel self ignites due to the heat caused by the higher compression there is no need for any of the spark generating and distributing components used in the gasoline engine.

THE INDUCTION STROKE (first cycle)

In this cycle the crankshaft rotates thus drawing the piston down the cylinder bore. This action draws pure air alone into the cylinder via the opened inlet valve. The exhaust valve is closed at this time.

THE COMPRESSION STROKE (second cycle)

Both the exhaust valve and inlet valve are now closed.

The crankshaft continues to rotate and this action forces the piston back up the cylinder bore. As a result of both valves being closed the pure air has nowhere to go, so compression of the air now takes place.

The ratio of compression is typically in the range of between (16 to 1) to (22 to 1) depending on the engines designed performance. This is much higher than that found in the gasoline engine and as a result the air temperature rises to well above 500 degrees Centigrade.

This has now completed one revolution of the crankshaft.

THE POWER STROKE (third cycle)

Both the exhaust valve and the inlet valve remain closed.

The fuel is now sprayed into the heated air just before the piston reaches the top of its stroke and as a result it ignites and burns with the oxygen in the air.

This results in a rapid burning (expansion) of the gasses which forces the piston back down the cylinder bore, and in the process turns the crankshaft.

This is Power.....

THE EXHAUST STROKE (forth cycle)

The inlet valve remains closed but the exhaust valve is now opened.

The crankshaft continues to turn, forcing the piston back up the cylinder bore.

Because the exhaust valve is now open the movement of the piston forces the burnt gasses out of the cylinder, through the silencer and out into the atmosphere.

This has now completed the second revolution of the crankshaft. The whole process is now ready to begin again at the induction stroke.

Re-Cap

The petrol "spark ignition" fuel engine, is more wasteful of fuel than the diesel engine. Fuel has a certain heat value, and heat is work. The petrol engine delivers only 22 -- 25 % of the theoretical work value of its fuel, while the diesel engine delivers 30 -- 36 %. (First advantage). Thus the diesel engine is said to have the higher thermal efficiency, which in terms of ordinary usage means that there will be a more economical consumption figure for a given load. The lower temperature, at which petrol ignites compared to diesel, limits the compression ratio within the petrol engine to a lower figure. It is known that the higher the compression the more efficient an engine becomes, so this gives the diesel engine its second advantage, because only pure air is compressed so that there is nothing to "pre-ignite". (You can hear pre-ignition in a petrol engine that has too far advanced timing of the spark. This manifests itself as a "rattle" when you are driving with wide throttle openings and occurs particularly at lower revs. This can also lead to the engine carrying on firing, and running, when the ignition key is turned off)

Just before the piston reaches the end of the compression stroke the diesel is injected into the combustion chamber through an injector nozzle mounted in the cylinder head (in much the same position as the spark plug in a petrol engine). During injection the fuel is split up into finely divided particles, and the mixture of these with the air forms an explosive charge that is ignited by the heat of the compression. Injection, of the fuel, is continued for a short period, during which the piston passes its highest position and begins to descend on the power stroke. The expansion of combustion only begins to have effect when the piston has passed the top of its stroke. When the fuel is cut off expansion of the gases still continues. The overall effect on the piston is a more sustained pressure than that associated with the petrol engine. (In other words the burning and expansion lasts much longer than in a gasoline engine).

To inject the fuel a special type of pump driven by the engine is employed and this is the distinguishing feature of the diesel engine. This pump also has to supply the fuel at just the right instant "injection timing" for the engine to work efficiently. A very important detail is that injection must cease cleanly and abruptly at the end of the delivery period without any trace of "after-dribble" of the fuel from the injector otherwise carbon deposits quickly form on the nozzle tip and excessive smoke will appear in the exhaust.

So, already you should see that the diesel engine has no high voltage electrics to go wrong and be affected by moisture as in the petrol engine (wet high voltage leads in the petrol engine will stop it from running as the high voltage will find an easier path to follow along the wet leads). Also, the diesel's higher thermal efficiency means lower running temperatures so there are less overheating problems in arduous conditions. And because of the higher compression ratios encountered, diesel engines are built far more strongly than the petrol engine thus helping its durability and reliability in the field.

The maximum speed of the diesel engine is also kept to lower revolutions per minute (RPM) than that found in the petrol engine. This is accomplished by the use of a governor. This means that speed regulation (as in power generators) is reliably controlled so that when there is no load on the engine the fuel supply is cut back. But once load is applied then the fuel supply is increased to maintain the set RPM.

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Problem Solving.

Now that you are fully armed with some insights into the workings of both types of engines, I will now endeavour to explain some of the simple essentials used in fault finding.

The most important point to remember is that your fault-finding technique should be one of a "process of elimination". Start with the electrics, then move on to fuel and finally (once these have been eliminated) look for mechanical problems.

The following information will not be a substitute for a trained mechanic armed with many workshop manuals, but rather a conglomeration of tips and hints that will hopefully enable you to get out of trouble. It is, in my mind, advisable that everyone has some basic knowledge in the field as the knowledge and abilities of the local drivers cannot always be relied upon.

Before attempting any diagnostics beware of the dangers.

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Trouble shooting Petrol Engines.

The engine will not turn over :-

If the engine does not turn over then the obvious place to start is the battery's state of charge and the condition of the terminals and leads emanating from it. Ensure that the terminal joints are clean and shiny. Both the copper (bright red metal) and the lead (soft grey metal) terminals can be cleaned with a penknife. Ensure all connections are tight. If this is all in order then turn on the headlights to check on the state of charge within the battery. If the battery and the fuses (Fuses melt in the event of an electrical overload and are found within the vehicles fuse box) for the ignition and starter solenoid are good then suspect the starter solenoid itself. (The starter solenoid is a component used to enable the small wire from the ignition switch to electrically close the contacts within the solenoid and thus allow it to pass the many hundreds of Amps that the starter motor requires to rotate the engine). To by-pass the starter solenoid connect one of your jump leads (from the tool kit) to the positive terminal of the battery and to the heavy cable on the starter itself (the one coming from the solenoid). Be very careful to avoid sparks and ensure the vehicle is out of gear. If all is good then suspect the starter motor brushes or windings.

The engine turn over slowly and the battery is good :-

Check for heat in the leads and terminals going to the starter. Heat means a resistance to the current and can be caused by frayed wires or corroded terminals. If the heat is generated within the starter motor (it will feel very hot to the touch) then suspect the windings.

The engine turns over but will not fire :-

First check to see if there is a spark at the sparking plugs. Connect a spare spark plug to one of the spark plug leads and then "ground" this plug to the engine block (by placing the threaded portion of the spark plug onto the engine block). If there is no spark then suspect the fuses that are in line with the wires to the coil and distributor. If there is voltage reaching here (you can find this with a voltmeter or the "light bulb tracer" found on page 15) then suspect the contact breakers within the distributor cap and ensure they have the right gap. (The contact breakers, within the distributor cap, regularly suffer from "pitting" of the contact surfaces and subsequent closure. This affects the ignition timing and can eventually lead to the engine not starting at all).

Some vehicles are fitted with electronic ignition which can be mostly discounted in the field as this system is far more reliable. Also inspect the cap inside and out for electrical "tracking". This will show up as crooked lines in the dirt of the cap. Any moisture will also lead the spark to follow the path of least resistance. Dry the components or expel the moisture using WD40 or another water repellant.

You can, in an emergency, by-pass the ignition switch by connecting a wire from the positive terminal of the battery directly to the high tension coil's "CB terminal". If the spark is visible on the spare plug it also could be that the plugs within the engine are fouled or have broken down. A weak plug will not spark under the load of compression as the voltage will find some other path to follow.

The engine has a good spark but will not fire :-

Suspect the fuel flow and quality of the fuel first. Check the tank, pipes from the tank, fuel filter and fuel pump. Lastly inspect the carburetor and air filter. With the air filter removed you will see fuel spray within the carburetor when the throttle is opened. Be careful here in case of a backfire and a flash back.

The engine turns over very quickly and smells of gasoline at the exhaust :-

In this case the engine is flooded with fuel. Remove the spark plugs and turn the engine over to expel the surplus fuel from within the cylinders. Then add a small amount of engine oil through the spark plug holes. This will boost the compression, which has been reduced by the petrol washing it away from the cylinder bores and piston rings.

All of the above are correct but the engine will still not fire :-

Check the ignition timing in case it has been altered and also the state of the toothed cam belt. If the toothed cam belt has too much free play it can slip a notch and thus displace the valve timing. Timing belts should always be replaced at the manufacturers specified intervals. More frequently if the vehicle is used in dusty or sandy conditions. Check that the compression is also within manufacturers limits by using a compression gauge in the place of a removed spark plug.

If a cylinder is not working :-

Pull off the spark plug leads in turn and listen to the engine tone.Be very careful as you could get a very high voltage shock. When a spark plug lead is removed from a bad cylinder the engine will not slow down and there will not be a change in the sound of the engine.

Once you have established which is the malfunctioning cylinder, increase the gap between the plug lead and the spark plug. You will here a clicking of the spark jumping the increased gap. This also boosts the spark voltage and can clean a fouled plug (fouled with carbon or oil) in some cases. If this fails then check the plug itself. Oily deposits on the plug indicates a failed plug or worn piston rings or worn valve guides. Black spark plugs are indicative of over fuelling "too rich a fuel / air mixture". White spark plug tips are indicative of over heating and too "weak" a fuel mixture. The correct colour is light brown to grey. It is worth mentioning here that the spark plugs must be of the specified type. All plugs are graduated in a heat range, also some plugs are or the "long reach" type whilst some are "short reach" and should never be mixed up.

If the engine is running unevenly and you have eliminated the spark :-

This could be the fuel flow through carburetor. One technique for clearing blocked carburetor jets is to rev. the engine up and close your hand over the carburetor briefly. This will draw an excess of fuel through the jets and often clear them. Be careful if you carry out this trick in case you get a flash back (flame back through the carburetor). If this does not clear the fault then a carburetor overhaul and clean is required.

Lack of compression :-

This is mainly due to a worn out or burnt valves (usually the exhaust). This is one of the reasons why it is of paramount importance to service the vehicle regularly and not forget to adjust the valve clearances at the same time. The other reason for lack of compression is that of worn piston rings or worn cylinder bores.

Inspection of the engine oil :-

If the engine oil is grey to white in colour then it has been contaminated with water (which has formed an emulsion with the oil). This is most probably due to a failure of the "cylinder head gasket" or the cylinder head itself being cracked. The "cylinder head gasket" is the seal between the engine block (main body of the engine) and the cylinder head (the smaller block on top of the main block that contains the spark plugs, valves etc.). The cylinder head gasket has to seal in the engine compression (and power stroke), plus seal in the cooling water and lubricating oil around the engine, so it is under a great strain and sometimes fails. Lesser amounts of water can build up in the oil due to repeated short distance running and the subsequent condensation. Water in the oil can also be ascertained by lighting the oil at the end of the dip-stick. If water is present then you will hear a crackling sound (e.g. bacon spitting in the pan).

Inspection of the exhaust :-

If the exhaust is black then this is a sign or over fuelling. If the exhaust is blue then it is a sign of lubrication oil being burnt with the fuel, (coming from worn piston rings, worn cylinder bores or worn valve guides). If the exhaust is very white and steamy then this is a sign of water passing through the engine (probably from the cylinder head gasket). If everything is in correct running order then the exhaust pipe metal itself will be white (for leaded fuel, this is the lead) or brown (for unleaded fuel).

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Trouble shooting Diesel Engines.

Trouble shooting diesel Engines

The previously discussed points for checking the battery, battery leads, solenoid and starter motor for the petrol engine apply here as well, although with the diesel engine there is no spark required to ignite the fuel so there are no spark plugs, HT coils, rotor arms, contact breakers etc.

If the above is good but the engine will not run :-

Check the fuel, fuel lines and fuel filters first. Check the diesel fuel itself for water, and when pumping from barrels, always check that the first fuel from the bottom is free of water (after the barrel has been standing for some time). Water is heavier so it will go to the bottom. In dusty conditions always pour the fuel through a clean rag so it can act as a filter. If the fuel is good then the chances are you may have an air lock in the system. This means you have to slacken off the bleed points from the injector pump to the injector and force the air out by bleeding the system (this is done by manually pumping the fuel at the fuel pump).

With diesels you also have "heater plugs" to aid in cold starting by raising the temperature inside the cylinder. If these are faulty they have to be replaced but if it is only the wiring from the "timer" (the timer controls how long the heaters are on for) then you can by-pass this by bringing a heavy gauge copper lead directly from the batteries positive terminal (+). These heaters take a lot of current so use a substantial cable, and do not leave it connected for more then about 15 seconds or you will destroy the heaters.

If you find water in the fuel :-

With water in the fuel you have to drain the tank, replace the filters and re-bleed the system using clean fuel throughout.

If all the electrics are dead and you still want to move:-

The diesel engine is compression ignition so the battery is not required for running the engine. To run the engine without a battery you first have to remove a "plunger" (situated in a component on the injector pump with a small electrical cable going to it) from the fuel supply line. This is used for cutting the fuel off and thus turning the engine off. If there is enough power left in the battery you can take a cable from the positive terminal of the battery directly to this component input lead terminal. You should then here it "click" as it opens the fuel way. Then you can push start the engine. To stop the motor, stall it by selecting a high gear and with the brakes on, release the clutch slowly.

In very cold climates :-

In very cold climates the diesel fuel can "wax" if it has not been supplied with the correct anti-freezing agents. This will cause the fuel filters to clog up. If you cannot get the right fuel or the additive to prevent this then you have to warm up the fuel to make it run free again (In an emergency, summer diesel can be turned into winter diesel by the addition of small amounts of kerosene or petrol but this is very bad practice).

If the engine runs unevenly and with black smoke from the exhaust :-

Suspect the condition of the injectors themselves. If they do not close off quickly enough then they will "dribble fuel", causing a carbon build-up to take place. Most modern injectors have a pre-set pressure cut-off set from the manufacturer and are not adjustable. With these you can take them apart, clean the components and then re-assemble. With the adjustable type you need an injector pressure gauge (crack off) to re-set the correct pressures, given in the manufacturers manual. Alternatively if you are really stuck, you can connect the injector to the injector pipe and observe the spray formation.

Be very careful of the high pressures involved here and do not get sprayed with fuel.

If the engine does not run on all cylinders :-

If a cylinder is inoperative then slacken off the injector pipes (at the injector) in turn and listen to the engine tone. No change in engine tone means you have found the faulty cylinder. The first component to suspect here is the injector itself, there after you have to check the compression. The compression is checked by removing an injector and fitting a special compression tester gauge where the injector came from. If the compression is low then it is probably due firstly to either worn valves, or, secondly it may be due to worn piston rings and cylinder wall.

Inspection of the exhaust :-

If the exhaust is black then it is a sign of over fuelling and can probably be caused by simply a dirty air filter or more seriously by faulty fuel injectors.

If the exhaust is blue then it is a sign of lubrication oil, coming from worn piston rings, worn cylinder bores or worn valve guides and being burnt with the fuel.

If the exhaust is very white and steamy then this is a sign of water passing through the engine (probably from the cylinder head gasket).

Miscellaneous information about diesels :-

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Useful Information.

Daily checks to be carried out.

Fuel

Cleanliness, quantity and a the state of the fuel filter.

Water

Quantity and condition of all the hoses, the radiator and the radiator cap .

Tyres

Including spare wheel, jack and repair outfit. Check the tyre pressures and also include the spare wheel. Look for thorns in the tyres in desert areas.

Oil

Quantity and colour. Also look for oil leaks around the engine.

Brakes

Check for operation, fluid level and fluid leaks, especially around the wheels.

Shock absorbers and suspension

Visually check the suspension and then bounce the corners of the vehicle to ascertain the condition of the shock absorbers. If the shock absorbers are faulty then the vehicle will carry on bouncing. Check the tightness of all wheel nuts.

Fan & alternator belts

Check for wear and slackness.

Cam belt (if fitted)

Check for wear and slackness.

Battery connections

Check the charge, water level and condition of the battery. Also check all of the supply leads from the battery.

Air filter

Check for both integrity and cleanliness (especially in dusty conditions).

Engine mounts

Check for wear especially in rough conditions. Rock the engine to ascertain how much wear there actually is in the engine mounts.

Grease points

A daily greasing is recommended if the vehicle has had to wade deep water.

Extras to carry and for the tool kit, in addition to the ones usually supplied :-

Most importantly. Do not forget, it is of little importance carrying such things as fan belts if you have not already checked that you have the required spanners with you. It is always a good policy to buy the highest quality tools available as there may be nobody around to borrow from in remote areas in the event of a breakage. Plus, a breaking tool can cause you injury.

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Richard Seremak
definitions20@gmail.com

Copyright © 2003, Richard Seremak, Last Updated 24/08/2011 14:57:58