Diesel Engine Repair And Maintenance - Diesel Engine Repair
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Diesel Engine Repair And Maintenance


At present, most trucks basically use diesel engines with high thermal efficiency and high power. Because trucks will encounter various road conditions when transporting goods, coupled with the large transportation volume, the maintenance of their engines is very important.

Robert Sikorsky, a famous American engineer, listed five main causes of engine wear in his book forever driving.

1. Corrosion and wear

After the fuel is burned in the engine combustion chamber, a large number of harmful substances will be produced. Generally speaking, every 100 gallons of gasoline produces 1-5 pounds of nitrogen and sulfuric acid. These substances will not only cause corrosion to the cylinder, but also rush into the engine through the three piston rings (upper ring, middle ring and lower ring), causing metal corrosion to the main components of the engine, such as cam and crankshaft. This corrosion cannot be eliminated only by the use of lubricating oil.

2. Corrosion and wear

After the engine is shut down, it will cool from high temperature to low temperature. This temperature change process will produce water-cooled condensate, and even ponding in the engine. This will cause serious metal corrosion to the engine, especially when the engine is restarted in a short distance and the engine temperature is too late to evaporate water vapor. This kind of wear cannot be solved by lubricating oil.

3. Dust

The engine needs to inhale air during combustion, and even the best air filtration device is difficult to prevent dust from being sucked into the engine with the air. Strong wear is caused by inhaled dust, which cannot be completely eliminated by lubricating oil. Especially in China’s dry, rainless and windy areas, this strong wear is more prominent.

4. Cold start dry friction

GM’s research shows that when the engine stops running for 4 hours, all the lubricating oil on the friction interface will return to the lubricating oil tank. At this time, start the engine. Since the oil pump does not have enough time to send the lubricating oil pump to all lubricating parts, the dry friction of periodic loss of lubrication will occur in a short time, resulting in serious abnormal and strong wear of the engine. This strong wear cannot be solved by lubricating oil. (according to other relevant data, this strong wear accounts for more than 70% of the total wear of the engine).

5. Normal wear

Wear caused by normal operation of the engine. After clarifying the causes of engine wear, we will also know the role of lubricating oil in reducing engine wear. At the same time, the importance of using anti-wear protection products to prolong the service life and maintain the engine is clarified.
In addition, although additives such as anti-wear agent, viscosity index improver, detergent dispersant, rust inhibitor and antioxidant exist more or less in all high-efficiency lubricants, it should be emphasized that the above additives are not equivalent to professional automobile maintenance products. In the actual use process, people often want to obtain maintenance products with excellent comprehensive performance, which requires the selection of a variety of additives, the use of composite technology and configuration process to produce composite products with wide applicability.
It is not easy to develop a good compound formula, and the use of additives mainly depends on the experimental results. Secondly, there is a synergistic effect between different additives, which may be positive or negative. Therefore, in order to develop good automobile maintenance products, we must fully understand the performance of various basic additives, and a large number of laboratory and road vehicle experiments are needed. This is why the professional automobile maintenance products compounded with basic additives are very different from the basic additives only used as various oil additives.

The Main Causes of "Three Leaks" in Diesel Engines

In case of oil leakage, water leakage and air leakage of the engine, it will cause problems such as increased fuel consumption, accelerated wear of parts, power decline and so on. To solve the three leakage problem, let’s first look at the causes of the three leakage problem.

The Main Causes of "Three Leaks" in Diesel Engines
1. Reasons
(1) During the operation of diesel engine, the friction and wear caused by the mutual movement of various components gradually change the shape and scale of various components.
(2) Due to improper maintenance, such as loose screws, missing or damaged sealing washers, etc.
(3) The disassembly and assembly of parts are not standardized, special tools are not used, and the installation does not meet the requirements, resulting in deformation, damage or unclean contact surface and poor sealing
(4) Aging parts, such as rubber sealing rings and rubber pipes, are corroded by oil or water for a long time, resulting in aging and deterioration.
We all know that the “three leaks” fault will cause damage to the engine, so what kind of damage will it cause? Maybe many friends don’t have a clear concept, so let’s have a look.
2. Damage condition
(1) Oil leakage
The oil leakage of the engine lubrication system will reduce the oil level and oil pressure in the oil pan. In serious cases, the parts will be burned without lubrication. The diesel leakage in the oil supply system will make it difficult for the oil circuit to enter the air, lack of power during startup, emit black smoke, and cause energy waste and economic loss.
(2) Leakage
The leakage of engine cooling system will lead to the increase of engine water temperature, poor operation and loud noise. In serious cases, it will even lead to engine cylinder pulling and safety accidents.
(3) Air leakage
The air leakage at the connection between the diesel engine body and the cylinder liner will burn out the cylinder gasket, making it difficult for the diesel engine to start and reduce the power. The air leakage of the diesel engine intake system will cause dust to be sucked into the engine cylinder. Therefore, it will accelerate the wear of cylinder liner, piston, piston ring, valve, air duct and other components, making it difficult for the engine to start, increase fuel consumption and reduce power.

Treatments for Engine "Three Leaks"

(1) Lubricated plastic pad
For oil leakage at the leak proof pad of diesel engine pipe joint, a thin double-sided lubricating plastic pad can be added on both sides of the leak proof pad and tightened to prevent oil leakage.
(2) Shellac
For leakage at the joints of diesel engine oil tank, water tank and crankcase, shellac can be soaked in alcohol and then coated on the cleaned joints. However, shellac is expensive and is usually used only in emergencies.
(3) Grease
When the paper pad at the oil pan, cylinder head, gear cover and crankcase rear cover of the engine leaks oil, as long as the paper pad is intact and the joint surface is clean, apply grease on both sides of the paper pad and tighten the bolts to prevent oil leakage. If a new paper pad is used, soak the new paper pad in diesel oil for 10 minutes before installation, then take it out and wipe it clean, apply a layer of grease on the joint surface, and then install it.
(4) Liquid sealant
When solid gasket defects (such as pits, grooves and cracks) appear on the engine, resulting in interface leakage and destructive leakage, apply liquid sealant on the cleaned solid gasket joint surface. After curing, a uniform, stable and continuous separable film sealing ring can be formed to prevent all leakage.
(5) Anaerobic adhesive
When the ventilation bolts, screws, studs, plugs, etc. on the diesel engine leak, apply anaerobic adhesive to the cleaned bolts, threads or screw holes, which can quickly solidify into a film, fill the gap of parts, bear large pressure, and have strong shockproof and anti tightness functions. If it is used on the thread of engine high-pressure oil pipe joint, the leak proof effect is better.
(6) Size recovery glue
In case of leakage at the shaft and shaft sleeve, bearing and bearing seat, valve and seat, self tightening oil seal, felt cup and packing on the engine, the maintenance compound can be applied to the wear parts of the cleaned mating parts. After curing, a film with high wear resistance, heat resistance and mechanical strength is formed. Then carry out machining such as turning, boring, scraping and filing to restore the geometry and matching accuracy of parts, so as to solve the problem of leakage.
(7) Bonding
When the oil tank, water tank, oil pipe, water pipe and other parts of the engine body cause leakage, apply the sealant to the cleaned damaged parts to achieve the leak proof effect.
I would like to remind you that the best remedy is to do a good job in daily maintenance, correctly operate the engine and avoid water leakage, oil leakage and air leakage caused by human factors.

Engine Maintenance

Correct maintenance can effectively prolong the service life of diesel engine, reduce failure rate and reduce cost. In order to improve your operation efficiency and reduce costs, please carefully understand the correct use and maintenance. Special fittings and oil shall be used.

Insist on oil change

Oil changes are often overlooked, but to be honest, they are very valuable. Fresh oil helps to lubricate the moving parts of the engine, absorb heat and reduce carbon deposition. To learn more about which oil is suitable for your truck’s diesel engine and the oil change frequency of your truck, please check your owner’s manual. You can also check the dipstick every few weeks. If you don’t have enough oil, top it up.

Replace the air filter
The working principle of air filters is similar, whether they are connected to gasoline powered or diesel powered engines. You can usually find them in the cold air collection box. For more information on how often the air filter of diesel engine is replaced, please check your owner’s manual. Once you know the recommended replacement interval, you can replace the filter when the time is up.

Replace the fuel filter

Diesel engines have two fuel filters. The primary filter is located between the oil tank and the engine, and the secondary filter is located near the engine. There will be no problem replacing both filters; Just unscrew the old filter, wet the gasket of the new filter, and then fix the new filter in place. Don’t forget to release the bubbles in the fuel system to ensure that fresh fuel flow is flowing.
Bleed the fuel system
Air in the fuel system can cause problems, such as lack of fuel flowing into the combustion chamber. When you change the filter, air will enter the fuel system, which is why bleeding the fuel system is an important step. To bleed the system, you need to open the fuel supply valve and use a manual fuel pump. Use the pump until there are no bubbles in the fuel.
Drain the water separator

Unlike gasoline, diesel fuel is easily polluted by water. For this reason, the diesel truck includes a water separator, which can be found near the fuel filter. The water separator is usually self-cleaning, but you need to let it go at regular intervals to keep the diesel clean. Open the drain valve and drain the water. That’s it!

For truck drivers, working outside all year round will inevitably encounter the problems of the vehicles they drive. Therefore, it is very necessary to understand some basic engine maintenance knowledge. More detailed common faults and maintenance methods of the truck engine will be shared with you one after another. Please keep an eye on our website.

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