Diesel Engine Care

GENERAL INFORMATION

Because a diesel contaminates the lubrication system oil faster than a gasoline engine, most manufacturers specify more frequent oil and filter changes.

Special diesel oils are widely available today and, according to reviews, are quite effective. However, any high-quality engine oil for gasoline engines will also be suitable for a diesel, as long as it is changed at specified intervals. Read the label on the container, where the manufacturer usually gives instructions for diesel engines. If nothing is stated on this label, check the label on the box in which the containers were packed.

On engines with an overhead camshaft, the timing belt must be replaced at the specified intervals. Otherwise, if the belt suddenly breaks, the piston may strike the valves. Repairing the resulting damage will cost you a considerable amount of money. In practice, there have been cases of belts breaking at mileages as low as 48,000 km, but this happened as a result of oil or water getting onto them due to leaks in the lubrication and cooling systems, respectively. However, if you decide to continue driving without replacing the belt after 58,000 km, your reluctance to spend time on timely belt replacement may later cost you significantly more time and money.

When replacing the fuel filter, buy the best one available. Some filters may look good externally but "do not perform their primary function well." Do not forget to also replace the O-ring on the filter housing. It should also be noted that on a diesel engine, it is equally difficult to prevent both fuel leakage and air ingress into the fuel system, which seriously disrupt engine operation.

If air enters the fuel lines, it may be necessary to bleed it out through the special bleed valve using the small hand priming pump, which is usually mounted on the high-pressure fuel pump for this purpose. Many modern diesels have fuel systems that bleed air automatically. Simply crank the engine with the starter, and the air will be purged.

It is difficult to prevent moisture from condensing in the fuel filter, so some diesel vehicles are equipped with a warning lamp on the instrument panel that indicates the presence of water in the fuel system.

Normally, when changing the oil, it is only necessary to check the condition of the filter. However, when the vehicle is operated under severe conditions, such as high humidity and large differences between daytime and nighttime temperatures, the condition of the filters should be checked more often.

All diesel engines smoke when cold, but this should not be excessive. One of the most common causes is a malfunction in the timing of fuel delivery by the high-pressure fuel pump, which is easily corrected by readjusting the injection timing using the marks on the crankshaft and the pump. This work is very similar to adjusting the initial ignition timing on a gasoline engine. The procedure can be performed with the engine not running; however, it is better to purchase a special injection timing light for diesel engines, which is clamped to the injector fuel supply line and flashes in response to the pressure pulses of fuel flowing through the line.

Another cause is fuel leaking past injectors whose fuel passage does not close fully, which can cause the cylinder to be flooded with fuel and, as a result, excessive smoke on startup. Apart from general injector cleaning and replacing injectors worn at a mileage of about 110,000 km, there is little that can be done at home to check their operation, other than removing them and having them tested on suitable test equipment.

New injectors are not cheap, but you can save a considerable amount by contacting a diesel repair shop and having the injectors calibrated at a reasonable price. The price of the service depends on the location of the shop and the presence of auto parts stores nearby.

However, you can extend injector service life by keeping the air drawn in by the diesel engine and the fuel filters clean, thereby counteracting injector contamination. For this purpose, it is recommended to periodically add small amounts of special cleaners to the fuel tank.

If the high-pressure fuel pump is properly maintained, it will function reliably for a long time. However, be warned that replacing it is a rather expensive undertaking.

Poor starting and low responsiveness of a diesel engine can be caused by many things: substandard glow plugs, clogged fuel passages leading to a drop in fuel supply pressure, faulty fuel lines, and even incorrect injector installation. Faulty glow plugs can easily be identified by how long the glow plug indicator lamp stays on.

Talk to diesel vehicle owners and you will find that none of them wants to go back to driving a gasoline car. Your turn may come too, if a diesel fully meets your needs.

Troubleshooting Table and Remedies for Diesel Engine with Bosch Fuel Injection System Fault / Possible Cause Codes Hard starting 1 – 9, 12, 13, 20, 22 Unstable idle 1, 2, 14, 18, 21, 22 Uneven idle of warm engine 2, 10, 13, 17, 20, 22 Engine misfires under load 1, 2, 4, 5 – 10, 16, 22 Loss of engine power 1, 4 – 7, 9, 10, 11, 13, 15, 16, 19 – 22 Increased fuel consumption 7, 9, 10, 11, 13, 14, 19, 21, 22 Engine does not stop 3, 21, 22 Poor acceleration response, black smoke in exhaust, loss of engine power 2, 5, 9, 10, 11, 13, 19 – 22 Blue-gray exhaust at maximum load (white or light blue) 1, 2, 4, 5, 8, 9, 13, 19, 22 Abnormal minimum and maximum idle speed 14, 15, 18, 21 Engine does not accelerate 1, 2, 4, 6, 8, 9, 10, 19, 20, 21 High-pressure fuel pump overheats 16 POSSIBLE MALFUNCTION / REMEDY Fuel tank empty or tank vent valve clogged. Refill tank, flush fuel lines, clean vent valve Air in fuel system. Bleed fuel system, eliminate air leaks Solenoid valve of diesel engine or starting fuel delivery regulator faulty. Repair or replace Fuel filter clogged. Replace fuel filter Low-pressure fuel lines clogged. Restore fuel line flow passages Low-pressure fuel lines clogged. Clean or replace fuel lines Loose connections, fuel lines leaking or broken. Tighten connections, eliminate leak Paraffin deposits in fuel filter. Replace filter, use winter/seasonal fuel Incorrect fuel injection timing. Adjust initial fuel injection advance angle Injector nozzles faulty. Repair or replace Air filter clogged. Replace filter element Cold start aid system faulty. Replace faulty glow plugs Injection distribution among cylinders does not match firing order. Reconnect high-pressure fuel lines in the correct order Abnormal idle speed. Adjust idle speed with adjusting screw Abnormal maximum idle speed. Adjust maximum engine speed with adjusting screw Bypass valve clogged or faulty. Clean calibrated passage or replace valve Delivery valve leaking (four-cylinder diesel) or two valves (six-cylinder diesel). Replace valve(s) Tension of governor buffer spring not adjusted. Adjust buffer spring tension Fuel injection advance coupling faulty. Repair or replace coupling Low compression. Restore compression Engine speed governor faulty or not adjustable. Adjust or replace governor High-pressure fuel pump faulty or not adjustable. Remove pump and send for repair