Diesel cars are renowned for their durability, but that doesn't mean they don't need to be taken care of.
Prices for used diesel cars in the West are falling. This is due to the fact that for a long time the volume of sales of new diesel cars was very high and therefore there are now a large number of them on the used car market. New diesel cars are much more expensive than their equivalent gasoline counterparts. In addition, the time has passed when the diesel range familiar to us today was limited to just one model. Today, manufacturers are able to supply the market with diesel engines that meet the highest requirements.
Regrettable countries, if any, in which diesel fuel costs the same as gasoline or even exceeds it. But even then, you will benefit, as diesel cars tend to have a longer life, but only on the condition that you have a high annual mileage. No savings are obtained only with small annual runs. You save on spark plugs, although it is clear that when using spark plugs with a replacement interval of 60 thousand km, the savings on them will be small. At the same time, you will lose out on more frequent oil and filter changes.
What attracts diesel
Modern diesel cars are attractive due to their ability to develop a lot of traction at low speeds, which is especially good for drivers who do not like to change gears too often. Most manufacturers offer turbocharged diesels to give the owner the opportunity to experience the beauty of a high-end car for himself.
If you are thinking about switching to a diesel, but do not know how to take care of it yourself, then we will say right away that keeping a diesel in good condition is no more difficult than a gasoline engine, despite their differences. We offer you a brief guide to the purchase, operation and maintenance of a diesel engine.
The mechanisms of a gasoline and diesel engine are not much different. Both engines are based on a four-stroke combustion cycle, but they do this in completely different ways.
While gasoline engines ignite the air-fuel mixture with spark plugs, diesel fuel is ignited by very high compression.
When a gasoline engine sucks in air and gasoline on the first stroke, the diesel only sucks in air, which is compressed to such an extent that its temperature rises to 800°C. The hot air ignites diesel fuel, which is injected into the combustion chamber of the cylinder just before the piston reaches BMT on the compression stroke. Because diesel engines have twice the compression ratio of gasoline engines, the fuel must be injected at very high pressure in order for it to fly into the combustion chamber and keep the fuel jet shaped. Due to the increased requirements for injection, the diesel high pressure fuel pump is a particularly precision-manufactured unit.
On older diesel models, high-pressure in-line multi-plunger fuel pumps were usually used. Now most modern diesel engines use more complex rotary pumps with constant fuel supply, as they work better at high engine speeds. Modern diesel engines use electronic fuel metering control systems to achieve close to ideal combustion. Many diesels are even equipped with exhaust gas aftertreatment converters.
There are two types of diesels, and the difference between them is how they burn fuel. Some use direct fuel injection. The name itself indicates the direct direction of the fuel into the cavity of the combustion chamber. Although this injection method is very efficient, its disadvantages are high noise and unevenness. For this reason, direct injection has been preserved only on diesel engines used in trucks. However, advanced diesel designs have largely eliminated these shortcomings, and most car manufacturers offer high-performance direct injection diesels.
In other diesel engines that do not use direct fuel injection, a small additional chamber is created in front of the combustion chamber, into which fuel is injected. This chamber is located on the opposite side from the nozzle installation site and the direction of movement of the fuel injected by it. This constructive technique allows you to increase the engine speed, but you have to pay for this with some loss of power.
Why is diesel noisy
The well-known rumble of a diesel engine is generated by the ignition of the fuel and the subsequent sharp drop in high pressure in the combustion chamber. The most clearly specific rumble of a diesel engine is heard after starting during the engine warming up at idle.
The diesel does not have an ignition system, but there is a system for pre-heating the combustion chambers of the cylinders using starting candles. In addition, the times of prolonged cranking of the engine by the starter and tedious waiting for the preheating end indicator lamp to go out are long gone. There are already quite a few manufacturers producing quick-start diesels, which take no more than a couple of seconds to start in winter. Some cars even have "starting handle", which can be directly controlled by the high pressure fuel pump to change injection timing, accelerate warm-up and reduce smoke emission at start-up.
Diesel care
Since diesel contaminates the oil in the lubrication system faster than a gasoline engine, most car manufacturers require more frequent oil and filter changes.
Special diesel oils are widely available today and, judging by the reviews, are quite effective. However, any high-quality carbureted engine oil will also work for a diesel, as long as it is changed at regular intervals. Read the label on the can, where the manufacturer usually gives instructions for diesels. If you do not find anything on this label, then look at the label on the container in which the jars were packed.
For engines with an overhead camshaft, the toothed belt must be replaced at the indicated intervals. Otherwise, it is possible that the piston will hit the valves when the belt suddenly breaks. Eliminating the consequences of the latter will require considerable financial costs from you. In practice, there have already been cases of belt breaks with a range of up to 48 thousand km, but this happened as a result of oil or water getting on them due to depressurization of the lubrication and cooling systems, respectively. However, if you decide to drive without changing the belt after a run of 58 thousand km, then your unwillingness to take the time to change the belt in a timely manner can turn out to be much more time and money for you in the future.
To replace the fuel filter, buy the best one available to you. Some filters may look good on the outside, but "fail to perform their duties". Don't forget to also change the O-ring on the filter housing. We also note that on a diesel engine it is equally difficult to prevent both fuel leakage and air infiltration into the fuel system, which greatly disrupt engine operation.
If air enters the fuel lines, it may be necessary to remove it from there through a special valve using a small hand pump, usually mounted for this purpose on the high pressure fuel pump. Many modern diesel engines have self-bleeding power systems. You just need to spin the engine with a starter, and the air will be removed.
It is difficult to prevent moisture from condensing in the fuel filter, so for some diesels, a warning light is provided on the instrument panel to indicate the presence of water in the fuel system.
Usually, when changing the oil, it is only necessary to check the condition of the filter. However, if the vehicle is used in difficult conditions, such as high humidity and large differences between day and night temperatures, check the condition of the filters more often.
All diesels smoke in the cold, but this should not be excessive. One of the most common reasons for this is a failure at the injection timing of the high pressure pump, which is easily corrected by re-adjusting the injection timing according to the marks on the crankshaft and pump. This work is very similar to adjusting the initial ignition timing on a gasoline engine. The operation can be done with the engine not running, but it is better to purchase for this purpose a special lamp for setting the injection timing on a diesel engine, which is fastened with a clip on the fuel supply pipe of the nozzle and flashes under the influence of fuel passing through the pipe.
Another reason is fuel leakage through injectors with a loosely closed fuel supply channel, which can lead to overflow of the cylinder with fuel and, as a result, to excessive smoking during start-up. Other than a general cleaning of the injectors and replacing worn out ones after about 110 thousand km, there is little that can be done at home to check their operation. Is it possible to remove them and give them to check on some control equipment.
New injectors are not cheap, but you can save a lot of money by going to a diesel repair shop and having your injectors calibrated for a very reasonable price. The price for the service depends on the location of the station and the availability of spare parts stores around it.
However, you can extend the life of your injectors by keeping the diesel intake air and fuel filters clean, and thereby counteract injector fouling. For these purposes, special cleaners should be periodically poured into the fuel tank in a small amount.
If you monitor the high pressure fuel pump, it will function for a long time and work properly. However, we want to warn you that replacing it is a rather expensive undertaking.
Poor starting and low throttle response of a diesel engine can be caused by many things: poor quality spark plugs, clogged fuel line channels leading to a drop in fuel supply pressure, malfunctioning fuel lines, and even improper installation of injectors. It is easy to identify poorly performing spark plugs by how long the preheat indicator light does not go out.
Talk to diesel car owners and you will see that none of them want to think about driving a gasoline car again. Perhaps your turn has come, if the diesel fully meets your needs.
Table of malfunctions and methods for their elimination on a diesel engine with Bosch fuel equipment
| Malfunction | Possible Reason Codes |
| Difficult start | 1 – 9, 12, 13, 20, 22 |
| Erratic idle | 1, 2, 14, 18, 21, 22 |
| Irregular idling of a warm engine | 2, 10, 13, 17, 20, 22 |
| Interruptions in engine operation under load | 1, 2, 4, 5 – 10, 16, 22 |
| Engine power drop | 1, 4 – 7, 9, 10, 11, 13, 15, 16, 19 – 22 |
| Increased fuel consumption | 7, 9, 10, 11, 13, 14, 19, 21, 22 |
| Engine won't stop | 3, 21, 22 |
| Poor throttle response, black smoke exhaust, engine power loss | 2, 5, 9, 10, 11, 13, 19 – 22 |
| Blue exhaust at maximum load (white or blue) | 1, 2, 4, 5, 8, 9, 13, 19, 22 |
| Abnormal minimum and maximum idle speeds | 14, 15, 18, 21 |
| The engine does not accelerate | 1, 2, 4, 6, 8, 9, 10, 19, 20, 21 |
| High pressure fuel pump is overheating | 16 |
Possible malfunction | Elimination method |
Empty fuel tank or clogged tank vent valve | Fill the tank, flush the fuel lines, clean the vent valve |
Presence of air in the fuel system | Bleed the fuel system, eliminate air leaks |
Faulty diesel solenoid valve or starting fuel supply regulator | Repair or replace |
Clogged fuel filter | Replace fuel filter |
Clogged low pressure fuel lines | Restore flow sections of fuel lines |
Clogged low pressure fuel lines | Flush or replace fuel lines |
Loose connections, fuel lines leaking or broken | Tighten connections, fix leaks |
Paraffin deposits in the fuel filter | Change filter, use seasonal fuel |
Incorrect fuel injection timing | Adjust the initial fuel injection advance angle |
Faulty injector nozzles | Repair or replace |
Air filter clogged | Replace filter element |
Faulty preheating system | Replace faulty spark plugs |
The distribution of injection on the cylinders does not correspond to the order of their work | Rearrange the high pressure fuel lines in the required order |
Abnormal idle speed | Adjust idle speed screw |
Abnormal maximum idle speed | Adjust the screw to the maximum engine speed |
Clogged or faulty bypass valve | Clean calibrated port or replace valve |
Discharge valve leaking (on a four-cylinder diesel) or two valves (on a six-cylinder) | Replace valve (s) |
The force of the buffer spring of the diesel speed controller is not adjusted | Adjust buffer spring force |
Faulty fuel advance clutch | Repair or replace clutch |
low compression | Restore compression |
Faulty or out of adjustment engine speed control | Adjust or replace regulator |
High pressure fuel pump defective or out of adjustment | Remove the pump and send it in for repair |
Buying a used engine
Be careful when buying a used diesel. Diesels last a long time, but that doesn't mean you shouldn't inspect all the traditional wear spots. On some engines, it is very easy to mask both life and wear. When assessing the condition of such an engine, there is a danger "burst", if you don't know much about diesels.
Like gasoline engines, diesel exhaust must be smokeless. In addition, no smoke should come out of the open neck of the oil filler pipe when the engine is warm. Since a diesel engine is noisier than a gasoline engine, you must distinguish between running noise and the sound of worn pistons, connecting rods, camshafts, etc. If you have any doubts about the condition of the engine, then seek the help of professionals.
Turbodiesels are very popular because turbocharging fits well with diesel performance. Turbochargers operate at low boost pressure and at low engine speeds, giving them a longer service life than gasoline engines. Turbodiesels are excellent for tractors and multi-ton trucks.
However, it is difficult for diesel automatics to meet the demands of an automatic transmission due to the flat torque curve. Only a few manufacturers are concerned about this problem. Among them are Citroen, Mercedes, Peugeot and the recently joined Opel, but even then they use automatic transmissions only on middle-class cars.
Thanks to their growing popularity, diesels are no longer looked upon as poor relatives, and in terms of their level of finish, they are fully consistent with their gasoline counterparts.
When buying, pay attention to the residual value of the diesel. At one time, diesel cars gave a boost to car sales in Germany, but sales peaked four years ago and are still in gradual decline, so make sure you don't overpay for the honor of owning a diesel car.
Check mileage. Diesel cars are snapping up for their potentially high reliability and possibly high mileage. Especially when they are bought new. But this does not mean at all that you should not pay attention to the odometer. Indeed, many dealers do not like to deal with cars whose mileage has exceeded 80 thousand km and, accordingly, adjust the price for them. Or, without further ado, they simply reset the mileage on the counter. A mileage of 160,000 is quite natural for a well-maintained diesel, but think twice if the meter shows 320,000 km or, especially, if it is a used taxi with such mileage.
With the exception of the engine, most diesel cars are identical in design to their gasoline counterparts, the same applies to suspensions, brakes, but consider the prices of spare parts. For example, exhaust systems last a long time, but differ from similar gasoline engines. And if you are used to buying parts from salvage car dealers, then keep in mind that gasoline engine parts may look similar and fit in size, however, the diesel engine block is different from the similar gasoline engine block and in most cases cannot be selected as a replacement. Gear ratios of gearboxes and clutches also differ.
Be healthy diesel
The motor sneezed once, twice, and then died down... Everyone who has been in such a situation probably knows what a swarm of questions flash through their heads during unsuccessful attempts to restart "heart" "iron horse". Owners of cars with diesel engines are no different from everyone else, but the causes of trouble with diesel engines and how to fix them are largely specific to this type of engine. In order not to complicate your life, it is better to listen to the advice of professionals who have solid practice in this area.
They were also contacted this time, having learned a lot of useful information and rather easy-to-implement practical advice.
The biggest surprise is that the engine that did not cause trouble yesterday suddenly completely refuses "come alive" right at the moment when you rush to work in the morning. If this happened for the first time, and even accompanied by a white exhaust, then with almost complete certainty we can say that the glow plugs are guilty. By the way, the indicator on the instrument panel may well be wrong, arguing that with candles everything "OK". To test, one end of the wire is brought to "plus" battery, and the second supplies voltage directly to the candles. If a good spark jumps at the same time (it is not difficult to distinguish it from a bright flash of a short circuit), the wire starts to warm up, and after that the engine starts, then the candles have nothing to do with it. The problem should be sought in the electrical circuits that supply voltage to them. This way you can also check the fuel supply valve.
And finally, blame only yourself if you tried to start the car on the move before. At the same time, the timing belt could easily slip through several teeth. It is not possible to start the engine and, perhaps, it is necessary to prepare for a complex and expensive engine repair.
As experience shows, another situation is also very common - the engine is idling, and when you try to add speed, it immediately stalls or stops after a little work. Most likely air has entered the fuel system. It is again worth paying attention to the exhaust. In this case, it is usually white with a characteristic smell of diesel fuel. A vacuum in the fuel stream can be caused by a blockage in, say, a fuel intake or fuel filter. Most often, it is the fuel filter that is clogged, and such troubles occur mostly in winter.
Company specialists "Technodiesel" advise everyone to adhere to the rule that has no exceptions: never repair fuel filters. Diverse "flushing", "blowing", and other supposedly restorative procedures, at best, simply will not give an effect, and at worst, they will further aggravate the situation. Fuel passing through such "restored" the filter, not only does not receive the prescribed cleaning, but also washes away all the dirt accumulated in it before. This can quickly disable the precision injection pump mechanism.
Another pseudo help to the motor that they like to provide "knowing" mechanics, - installation of several fuel filters. From the point of view of achieving unprecedented purity of diesel fuel entering the engine, there is no point in this multi-stage filtration. Diesel car manufacturers make accurate filter performance calculations that are backed up by a series of tests, so they should be trusted. Additional filters are not just useless, but harmful. They create excessive resistance, due to which the high-pressure fuel pump works with overload and fails faster. Increased resistance in the piping can also cause air to be sucked in.
You should not be led by another fairly common misconception that additional filters help separate water from the fuel. In fact, filters do not retain water; for this, there are special settling tanks-separators. The presence of such a separator is indicated by a small plug from below under the filter. The accumulated moisture should be drained approximately every 3000 km. It is necessary to drain the liquid until almost clean diesel fuel flows.
The presence of water in the fuel also causes white exhaust clouds. Some modern diesel vehicles have an indicator on the instrument panel that will tell you if there is water in the fuel. If the indicator lights up, it is better, without delay, to stop, turn off the engine and drain the liquid from the separator. If necessary, you can repeat the procedure. If after that the indicator does not want to go out, then the problem is probably in the electrical circuits of the system for indicating the presence of water in the fuel. Trying to fix something to the bottom in haste is not worth it, it is better to contact a car service.
It also happens that a regularly buzzing engine suddenly stops for no reason. The most trivial advice, which, oddly enough, helps in many "heavy" cases - make sure that there is still diesel fuel in the tank. If things are worse, and something really happened, it is worth remembering if there was any sharp sound before the engine stopped. This sound is accompanied by a broken timing belt. If so, then it is better not to try to scroll the motor - the consequences can be devastating.
Another reason for the sudden stop of the engine may be the same air in the fuel system. You can try to directly connect the fuel pump to any container with diesel fuel. If the engine starts running, then the cause has been found. For any problems with the fuel pump, it is best to contact specialists, not trusting repair to dubious mechanics.
When the injection pump is excluded from the likely culprits of the trouble, you can try to loosen the fittings on the nozzles. If, during attempts to start the engine, diesel fuel begins to flow out from under them in a pulsating stream, this means that faulty nozzles do not provide a normal supply of fuel to the combustion chambers. You may notice that black exhaust smoke is pouring out - this is one of the signs of a stuck needle in the nozzle. Fuel begins to flow uncontrollably into the cylinder, and the black exhaust is due to its incomplete combustion.
Attention! And one more thing - no need to famously ride through deep puddles. Masters often have to see the engines of diesel cars crippled after such a bath. Water from the puddle enters the combustion chamber, and the strongest hydrodynamic shock bends even the strongest connecting rods!