Diesel does not start well or does not start when cold, reasons why it smokes white or black

Are you looking for why a cold or hot diesel car has trouble starting in winter or summer? Why doesn't the diesel engine start in the morning and why does it smoke white, blue or black? In this article, you will learn why a diesel engine has trouble starting or starting when hot or cold and why white, blue or black smoke comes out of the exhaust pipe.

Almost all owners of diesel cars are faced with the problem of the inability to start the engine in winter, or the engine does not start well - it often stalls. What are the reasons and what to do to make the car run smoothly?

Reasons why a diesel engine does not start or starts poorly?

In cold weather it is difficult to start the engine. This is especially true for diesel engines.

There are many reasons why an engine starts poorly or does not start at all:

• Low compression in cylinders
• Fuel lines and fuel in them are frozen
• The engine oil has thickened.
• Low battery, faulty starter
• Wrong glow plugs
• Air pressure in the fuel system is too low
• Water in the filter
• If the engine is not young enough, severe burns may result.

Low compression in cylinders

If the engine is no longer young, starting in cold weather may be difficult due to the low compression ratio in the cylinders.

The problem with a worn out, old engine will appear after a long period of inactivity and it will be difficult to start a warm engine. After starting, such an engine will show incorrect speed, moreover. In neutral, a diesel engine can vibrate and even limp.

The reason for such inefficient engine operation lies in poorly worn parts of the cylinder head: gaps form between them, the tightness of the cylinders decreases, and compression decreases. As a result, the fuel-air mixture is not compressed enough and heats up.

And after the diesel engine warms up to operating temperature, the gaps between the cylinder head elements decrease under the influence of heat, the tightness increases and the engine begins to operate more stably.

Fuel is frozen

This is the most common and common reason why we do not start the car in winter. After a night in the cold, diesel fuel thickens to the consistency of a gel, especially if the car owner has not switched to winter diesel or did not use antifreeze additives.

When wax crystals form in diesel fuel, they clog the fuel filter. Therefore, it is very important that all diesel car owners replace the fuel filter annually before winter.

To avoid trouble, use the right fuel additives, and it's best to fill up with good quality fuel before the cold weather sets in.

In advanced cases, you will have to flush and often repair the diesel fuel system.

Another reason why the fuel is not being pumped is that water has entered the fuel and has frozen in the filter.

Depending on the version, the fuel filter does not require maintenance (i.e. it needs to be changed every 30,000 km) or has a water drain. The amount of water that accumulates in the filter depends on the quality of the fuel, ambient temperature, number of engine starting cycles, etc. If you don't empty the fuel filter from time to time, extreme cold can cause ice blockage to form. to completely shut off the diesel fuel supply to the engine. Worth checking: If your car's filter has a drain plug, it's a good idea to use it from time to time. Also, don't hesitate to replace the fuel filter.

To prevent this from happening, keep your fuel tank as full as possible in winter, use winter diesel, or add a drying additive. In addition, many diesel engines have a special drain plug near the fuel filter that should be used to drain water that accumulates from time to time. It's worth finding out if there is such an element under the hood.

If the oil in the diesel engine crankcase is too thick or its viscosity coefficient is not suitable for winter use, the engine will not start.

Therefore, it is worth taking out the dipstick and checking the condition of the oil and its consistency. If it is sticky and does not leak, change the engine oil.

The battery is discharged, the starter is stuck

The battery can withstand extreme loads in winter.

If it is old or has a very low charge level, the crankshaft will not rotate enough to create pressure and the glow plugs will not heat up to heat the fuel properly.

In winter, it is more difficult for the starter to unscrew the crankshaft because engine oil thickens in the cold. When worn, it can jam - it starts, clicks, but the engine does not start.

They heat the air in the combustion chambers so that when compressed by the movement of the piston, its temperature rises to a level at which the mixture ignites. In older engines, activation is two-stage: first turn on the ignition key, at the same time turn on the glow plugs and wait until the “heating” light goes out - this takes 20-30 seconds.

In newer installations, the air in the combustion chambers is preheated much faster and the engine is ready to start almost immediately. In this case, the glow plugs usually last a long time. When they fail, even if the engine can be started (it can), after starting it shakes, makes noise for several minutes, and when we try to start it, it turns out that there is no electricity.

Glow plugs break either individually or in groups - the number of “dead” plugs depends on whether the engine can be started at all. For most models, purchasing glow plugs is not a big expense; it is worse to replace them.

Damage to glow plugs is not easy to detect: even with 1 or 2 faulty spark plugs, you can start the engine, even if it is -5 outside.

Low-quality glow plugs do not last more than one season, so you should not skimp on the quality of glow plugs.

Check the glow plugs by unscrewing them and measuring the resistance. A delayed engine start will alert the owner to a problem with the glow plugs.

The absence of a characteristic sound (soft click) when turning the ignition key before starting the diesel engine is a sign of a malfunction of the relay or controller.

Keep in mind that in cold weather, even fast-heating glow plugs can take a few seconds to fire - don't engage the starter too quickly!

Air and fuel enter the cylinders of a diesel engine separately. If air becomes blocked in the fuel system, the engine will stall.

Air enters the fuel system through leaks. To remove the plug, the fuel injector and lines are bled.

Diesel injectors become clogged over time with fuel deposits, rust particles, etc.

Worn out and dirty injectors do not work properly and do not pump or distribute fuel into the combustion chamber. As a result, the diesel engine becomes unstable, may choke and lose power.

If your diesel engine starts well when cold, but refuses to start when warm once warmed up and at operating temperature, the problem is a pair of high pressure fuel pump pistons. The solution is to repair or replace the fuel injection system.

The color of the exhaust gases will also help identify the reason why a diesel engine has difficulty starting in cold weather and is unstable.

The exhaust from a working car is almost colorless. But what if the color came out?

Diesel engine smokes white

White clouds do not always mean that there is something wrong with the car. If they stop appearing after a while, there is nothing to worry about. White smoke is often just water vapor accumulated in the exhaust system, for example. This is more noticeable at low temperatures.

However, white and dense exhaust gases leaving the system despite long distances are a bad sign. The head gasket or the head itself may be damaged. White smoke comes out as coolant enters the cylinders. We may feel engine vibration or loss of power and notice loss of coolant.

Diesel engine light blue

The blue color of the exhaust gases indicates that the engine is burning oil entering the chambers. There may be serious shortcomings here. Piston rings or cylinder liners may be damaged.

Blue smoke can also be a sign of worn valve seals or a broken turbocharger.

Diesel engine burns black

Black plumes of smoke are common in diesel engines. This can happen when the engine is starting or when the engine is under load.

If the black exhaust is visible even when driving slowly, and not when the accelerator pedal is pressed sharply, it means that the injection system is faulty. It may be necessary to replace the fuel pump or the injectors themselves. There is also a possibility of damage to the exhaust gas cleaning system. Black smoke could be a sign of a damaged turbocharger or leaking rubber intercooler ducts.

Black gas is less common in gasoline engines. In their case, a dark color may indicate problems with the drive control system, for example, as a result of a less than professional setup of the chip. Too much fuel is consumed.

Diesel fuel froze in diesel engine

The reason why a diesel engine does not start well in the morning may be a discrepancy between the operating conditions and the fuel parameters. In the warm season, diesel fuel, which contains impurities, is used to operate the power unit. With the onset of cold weather, impurities turn into a viscous substance that settles in the fuel system pipelines, filter elements and high-pressure pump.

If a diesel engine has difficulty starting when cold due to freezing of diesel fuel, the motorist can independently identify the breakdown. Diagnostics and troubleshooting is carried out in the following order:

1. Check the presence of fuel in the tank.
2. Remove the filter element.
3. Inspect the filter for the presence of viscous deposits.
4. Clean the filter element. To remove frozen impurities, the part must be heated.
5. Install the filter into place.
6. Warm up the fuel line leading from the tank to the high pressure fuel pump (HPFP).
7. Unscrew the return pipeline and pump in diesel fuel.
8. Start the diesel engine.

Motorists use specialized additives that prevent fuel from freezing. In some cases, if the engine does not start when cold, disassembly and restoration of the fuel system will be required.

Fuel

The less often we refuel the car, the wiser it is to refuel with premium diesel fuel in winter. From regular diesel fuel, paraffin has the right to precipitate at a temperature of -20ºC - even if today it is only -5ºC, in two weeks it could be -25ºC - and then we simply won’t start the engine! Although fuel sellers have to adjust the quality of even basic diesel fuel to prevailing weather conditions, firstly, not all of them work quickly enough, and secondly, the fuel sometimes remains in the tank for several weeks. Investments in quality fuel will pay off.

Diesel engine emits gray smoke

Diesel exhaust color

The color of the smoke determines the performance of the diesel engine. The presence of blue or gray smoke indicates incomplete combustion of fuel in the working cylinders.

Light gray smoke occurs when lubricant enters the working chambers of the engine.

The vehicle owner determines the malfunction by increasing oil consumption.

Supplying a large amount of diesel fuel into the cylinder leads to the formation of black smoke in the exhaust. This color of smoke is associated with malfunctions in the fuel supply system.

Results

Strong-smelling gray exhaust gas may indicate that the engine's air-fuel mixture is too rich. The fuel level may be too high, for example due to a faulty temperature sensor.

• There are many reasons why a diesel engine does not start in cold weather.
• To successfully combat diesel in winter, you need to prepare for the onset of cold weather:
• charge the battery (replace with a new one), make sure that the generator is in good technical condition
• replacing engine oil and filter
• check the serviceability of the glow plugs
• replace fuel filter

• changing fuel to winter
• drive with a full tank of gas

In most cases, if these measures are followed, problems with starting a diesel engine at low temperatures will not arise.

The article describes the reasons why a diesel car (diesel engine) does not start for the following brands of cars:

However, if the engine does not start cold, try adding warm fuel to the tank or warming up the diesel engine by pointing a construction (household) dryer to the fuel filter and gas tank. After 10-15 minutes, only warm fuel will flow back into the tank, and only then you can hit the road.

If the problem is a discharged battery, try to “ignite” the engine, or better yet, remove, heat and charge the battery.

Starter and battery

Most problems with these elements appear more often during the cold season. With an undercharged battery and/or a faulty starter, a diesel engine always starts poorly, but starting a diesel engine in cold weather involves a whole host of difficulties. If there is a minus overboard, the battery noticeably loses its charge.

A weak battery means:

• the inability to rotate the crankshaft of a diesel internal combustion engine at the required frequency to create pressure;
• insufficient glow of spark plugs to heat the fuel-air mixture in the cylinders;

Any oil in the cold becomes more viscous in the engine crankcase. It becomes more difficult for the starter to crank the crankshaft of a diesel engine in conditions of low temperatures and thickened engine oil. If the starter is worn out, the starter is jammed, or there are extraneous sounds from the starter when starting the diesel engine, then this may be the reason for the poor start.

Possible causes and solutions to the problem

Imagine this situation. You wake up early in the morning, rush to the garage and get into the car. Turn the key in the ignition and... The car will not start. Probably every car owner has encountered such a situation. The problem with starting the engine is one of the most unpleasant. You really need to go, but the car is standing still. Panic sets in. What to do if the diesel engine does not start? The reasons and ways to eliminate them are further in our article. In gasoline units, a mixture of air and fuel is created, which is injected into the cylinders by an injector. After entering the combustion chamber, the mixture is ignited by the spark plug and the working stroke occurs. Then exhale, compress, and then the cycle repeats. Unlike gasoline engines, in a diesel engine the mixture ignites under high pressure. It enters the combustion chamber through the nozzles. Additionally, the operation includes a glow plug, which heats the fuel to the required temperature.

However, if they fail, the diesel engine will not be able to start properly. The glow plug greatly simplifies the process of igniting the fuel and, therefore, starting the engine. If the diesel engine does not start “cold”, it means that the control relay is faulty and the glow plug is not heating the fuel. This element operates until the coolant temperature reaches operating values. Glow plugs often saved car owners when starting the engine in winter.

Low battery level or problems with the starter

A normally charged battery can cope with loads at any time of the year. But if the battery is old (more than three years old), problems cannot be avoided. The crankshaft will not rotate at the required frequency, which is why the required pressure in the system will not be created, and the glow plugs will not warm up to the required temperature.

A faulty starter is another reason for difficult starting. In this case, clicking and “buzzing” sounds will be heard when starting. All this suggests that the device needs to be replaced.

And one more thing about the battery: when choosing a battery, you need to take into account its starting current, which should be at least 320 amperes.

Compression

It should also be remembered that, in addition to the ignition method, these engines differ in the design of the fuel system. And if gasoline ones have a simple submersible pump, then there are two of them: one for low pressure and the other for high pressure. Well, let's look at why diesel is not "hot".

What is normal compression?

Initially, its level is twice as high as that of gasoline units. The mixture ignites as a result of strong compression. And loss of compression does not have the best effect on engine starting. Since each compression process is accompanied by the release of thermal energy, the mixture does not heat up enough and cannot ignite. If it's a high-mileage car, compression decreases as the cylinder walls wear and rings rupture. Recall that each piston has three rings. Two compressions, one with an ice scraper. Here it is necessary to disassemble and repair the engine. It happens that compression drops in only one of the cylinders. In this case, the diesel engine may start and either stall or fail. This means that one of the cylinders is faulty or the ignition is unstable.

Diesel won't start

A diesel engine that cranks normally but does not start regardless of outside temperature either has low compression or has a fuel delivery problem. If compression is OK, check the fuel gauges. Next, check the fuel filters and fuel lines for blockages.

If the fuel pump is not pushing fuel through the lines to the injectors, this may indicate a faulty solenoid. Listen for a "clicking" sound inside the pump when the ignition key is turned on. No clicking noise means the pump and/or solenoid needs to be replaced. If it clicks but there is no fuel flowing through the injector tubes (and the filter and lines are not blocked), the pump is likely bad and needs to be replaced.

Filters

As we said earlier, its design is significantly different from its gasoline counterparts. In 60 percent of cases (including Ford cars), diesel engines do not start due to problems in the fuel system. The first thing that could be clogged is the injectors. This is due to poor quality fuel. You cannot clean them yourself - only in a specialized service.

For what other reasons does a diesel engine not start? Of course these are filters. It is necessary to check their condition.

There are two cleaning stages in the fuel system of a diesel engine - coarse and fine.

The latter requires special attention. The filter paper recess through which fuel enters the injectors is capable of trapping particles as small as 10 microns. The resources of this element are 8-10 thousand. km. If you do not follow this recipe, the filter will simply become clogged. As a result, fuel will not enter the combustion chamber, despite the fact that the pump creates the necessary pressure. This can be determined by the nature of the vehicle's movement. If there are gaps in dynamics, it means that fuel is delivered late. And it is delayed by a filter clogged with dirt. It is also worth mentioning the element of air.

Water in the fuel system of a diesel engine

After starting the engine, the diesel fuel unused by the sprayers enters the vehicle tank. As the liquid passes through the system, it warms up. During the cold season, due to temperature differences, condensation forms on the internal surfaces of the tank. The water sinks to the bottom of the container, where the liquid intake pipe is located. The presence of water in the fuel makes the engine difficult to start when cold.

The surfaces of the moving components of the pump are lubricated with diesel fuel. The ingress of water leads to increased friction and rapid wear of parts, disrupting the operation of the injection pump.

The motorist must independently monitor the appearance of water and eliminate it in a timely manner. To do this, periodically remove the sump filter drain plug. The water collected in the container will flow out.

Fuel and winter

The system has two mechanisms. This is the injection pump and the injection pump injector. Very often the first element fails because its design is more complex than the second. The pump cannot create pressure in the fuel system, so the diesel engine will not start or is difficult to start. The trip is accompanied by “sneezing” (as if the car is running out of fuel). It is worth paying attention to the fact that the belt goes to the injection pump. It may tear or fall off. First of all, you need to check the belt drive. Check the fuel system fuses (going to the pump). One of them can be blown up. This often occurs due to a short circuit. Experienced drivers are advised to always keep a set of spare fuses in their glove compartment.

Glow plugs

If the engine turns over slowly, this is not a problem; there may be something wrong with the glow plugs. Most passenger cars and light trucks with diesel engines have glow plugs to assist with cold starts. The glow plugs are powered by a relay and timer that sends voltage to the plugs for a set number of seconds. When the timer expires, the relay is supposed to turn off the voltage. But at some point, the relay may become stuck and continue to supply voltage to the glow plugs, causing them to burn. One or two bad glow plugs on a V8 engine may not cause noticeable starting problems in warm weather, but it can happen when temperatures drop.

Check the operation of the glow plugs

Glow plugs can be tested by measuring their resistance or continuity. Excessive resistance or lack of continuity indicates that the spark plug needs to be replaced.

If one or more glow plugs are burnt out, heavily carbonated, or not receiving their normal dose of starting voltage, the engine will become increasingly difficult to start as the temperature drops. If all the glow plugs light up at the end, you'd better check the injection timing because that's probably the cause.

To see if the glow plug module is providing power to the glow plugs, use a voltmeter to test each terminal for the specified voltage while the ignition key is turned on. No voltage? Check glow plug control module connections, ground, and wiring harness. The glow plugs themselves can be tested by measuring their resistance. Replace any spark plugs that you find unsuitable.

Hard starting can sometimes be caused by a glow plug module that doesn't turn on the glow plugs or doesn't keep the glow plugs running long enough when the weather is cold.

Firing angle

Diesel engines also have this parameter. If it does not meet the standard, the motor will work intermittently. Excessive vibrations are noticeable, the diesel engine is bad. The reasons are an incorrectly set ignition timing. Also, this parameter may be “knocked down”. How to set the ignition correctly? This procedure requires certain skills. Setting the advance angle implies adjusting the fuel injection, which is supplied at a specific moment at the end of the compression stroke. When deviating from normal parameters, incomplete combustion of fuel in the cylinders occurs. Because of this, detonation and shaking at idle are possible.

How to set the ignition correctly? The parameter is set by rotating the fuel pump around its axis. The angle is also set by turning the camshaft pulley. To proceed to the adjustment, you need to get to the engine flywheel, after first removing the casing from it. You should find the stopper on the flywheel that drops into the slot and turn the element using a key.

This will set the crankshaft in motion. The flywheel must be rotated clockwise until the locking mechanism engages. Next, we find the injection pump drive shaft. Diesel shouldn't leak on it. Align the marks on the pump flange and on the drive coupling. Next, turn the crankshaft one more revolution and see if the marks match. Then we control the position of the scale. After tightening the drive coupling, lift the stopper on the flywheel. The shaft rotates 90 degrees. The stopper should be placed in the groove.

The final stage involves installing the flywheel housing and tightening the mounting bolts. We start the engine and check its operation. At idle, the engine should not emit unnecessary vibrations, and the movement should be without dips or jerks.

Injector problems

Diesel injectors can suffer from the same types of problems as gasoline injectors, including varnish deposits, clogging, wear, or leaks. Today's diesel vehicles are fueled with low-sulfur fuel, which can lead to deposits forming on the injectors and reducing the amount of lubrication needed. So you could try using a special additive to help the parts move more smoothly.

Check the condition of the injectors and, if necessary, clean them

Diesel injectors operate at higher pressures than gasoline injectors. Over time, their blood pressure may drop. A pressure level of up to 4.5-5 bar is still considered acceptable, but anything above this value means that the injectors must be replaced. You will need some type of pressure gauge to check the opening pressure of the injectors if you suspect that this kind of problem may be causing the malfunction. Dirty injectors will suck fuel mixture, causing loss of power, rough idling, and sometimes white smoke from the exhaust.

There are several ways to find a faulty injector on a diesel engine. One is to use a digital pyrometer to check the operating temperature of each cylinder. A temperature value that is lower than the others indicates a weak cylinder. If compression is good, the problem is limited to fuel delivery. Another quick method is to use an ohmmeter, which reads tenths of ohms, to measure the resistance of the glow plugs while the engine is running. Plug resistance goes up with temperature, so if one or two cylinders read "low", you've found the problem. For example, if the glow plug normally produces 1.8 to 3.4 ohms on a hot, running engine, then a reading of 1.2 to 1.3 ohms on the glow plugs will tell you that the cylinder is not producing any heat.

How to check the pressure in the fuel system

Adviсe

Below we will highlight some tips on how to start a diesel engine in cold weather:

• Keep your battery healthy. In 80 percent of cases, the problem lies precisely in the planted battery. Do not use a battery that is too old, 5 or more years old. To be more confident, you should buy a “booster” that will provide starting current regardless of the degree of discharge of your battery.
• How to start a diesel engine in cold weather? If starting in cold weather, you should “wake up” the battery. To do this, turn on the car's headlights for a few seconds.
• If there is severe frost, take the battery home overnight. Also periodically clean the terminals on the battery if they are oxidized. To do this, use special aggressive sprays or sandpaper.
• Choose the right oil. Remember that it thickens as the temperature drops. But changing such oil “on the spot” will not work. On cars with mileage less than 100 thousand kilometers, it is recommended to use synthetic or semi-synthetic oil with a viscosity index of 0W or 5W.
• Before long-term parking, you can pour 100-150 milliliters of gasoline into the oil. The fuel will dilute the lubricant, and the engine will start “cold” without any problems. The procedure does not harm the engine, but you should not abuse it.
• Before starting the starter, hold the key in the third position for a while. During this period, the glow plug will have time to heat the fuel and prepare it for ignition. As a rule, modern cars display a corresponding icon on the instrument panel.
• If the engine does not start within 10 seconds, turn off the starter. Otherwise, its prolonged operation will lead to a strong discharge of the battery. As a rule, 1-2 seconds are enough for the motor to start.
• Use anti-gel. Moreover, you need to fill it into the tank before refueling.

• In extreme cold, the first 1-2 kilometers should be driven at low speeds and revs so that all components of the car warm up properly.

Prices for injector repairs

Free consultations by phone

Diagnostics of pump injectors on a bench (with printout)

Injector repair (mechanical)

250 — 350

Injector repair (Common-Rail) Bosch (with printout) 1500 - 7500

Injector repair (Common-Rail) Delphi (with printout) 1500 - 5500

Repair of a pump injector with adjustment on a stand and printout of the protocol (excluding the cost of spare parts) 1500 - 4500

Oil too thick

As you know, diesel engines use a different lubricant than gasoline engines. However, this does not insure the car against difficult starts, especially in winter. As the temperature drops, the engine oil begins to thicken. Even with a charged battery, it will be difficult for the starter to turn the flywheel, and with it the crankshaft. Typically, diesel engines use motor oil with a viscosity of 15W-40.

When operating in extreme conditions, experts recommend lowering the bar to 5W-30. Thinner oil helps the crankshaft rotate more easily, which is especially important for an engine with lower temperatures.