Carbon Deposit and Overheating Issues in Excavator Engines

The performance and life of the engine, the heart of heavy machinery such as excavators, largely depend on a stable operating temperature. However, engines have some common and complex failures, such as carbon accumulation and overheating of the engine. These issues can not only affect the normal operation of the engine, but can also lead to serious mechanical damage, which in turn increases maintenance costs and downtime. The formation of carbon deposits is mainly due to the deposits caused by incomplete combustion of fuel and oil at high temperature, and overheating is usually due to problems such as the decline of heat dissipation capacity and insufficient cooling water. This paper will deeply discuss the causes of excavator engine failure, and provide effective maintenance and preventive measures.

Carbon Deposit

Carbon accumulation is a mixture that accumulates on the valve, combustion chamber and intake pipe of an engine. When the engine is working, the unsaturated olefin and gum in the oil and fuel will be produced by incomplete combustion at high temperature. This black scorched substance is often called carbon deposit, and carbon deposit can be divided into valve, combustion chamber carbon deposit, piston carbon deposit and intake pipe carbon deposit. Whether it is a crawler excavator or a wheeled excavator, the workplace environment is very harsh, and there is no guarantee that there are other pollutants in the fuel, so the occurrence of carbon deposition is more frequent than the car.

Production of Carbon Deposits

Fuel Impurity

In fact, it is impossible to achieve 100% purity, and the filter will also have a filtration limit, so some small impurities in the fuel are carbonized and deposited in the cylinder after combustion.

Intake Air

Two filter elements (coarse filter, fine filter) can not guarantee 100% of the filter out of the air. These fine dust enters the combustion chamber with the gas, and is deposited in the cylinder after combustion and carbonization.

Wear of Moving Parts

The moving parts in the cylinder, cylinder liner, valve, piston, piston ring, etc., will produce wear debris during high-speed movement, and these debris will be deposited in the cylinder after melting.

The Harm of Carbon Deposition

Speaking of the harm of carbon deposits, the first thing to know is where carbon deposits are deposited. Carbon deposits after combustion, after explosion impact, will eventually be deposited into the piston ring groove, injector nozzle, valve.

Deposited in Piston Ring Groove

Burned carbonized deposits accumulate in the piston ring groove, will accumulate more and more, stick to the piston ring, and eventually deform the piston ring, protrude, scratch the cylinder liner, causing the cylinder to pull and bite the cylinder. Cause cylinder liner piston ring all scrapped.

Deposited in the Injector Nozzle

The end result is to block the fuel injection port, and the current technology is basically unable to repair the fuel injection port of the electric injector, and the injector can only be replaced.

Deposited at the Spiracle

Too much accumulation will cause uneven valve force, valve rod fracture, valve chassis fracture. The result will be valve, lock plate, seat ring, piston, all damage.

It can be understood from the above that carbon deposition in the engine can cause very serious consequences, so it is necessary to carefully understand the situation of the machine, especially the machine with a long year and many hours. Pay attention to whether the momentum is stable, whether it is declining. Once there is a problem, it should be repaired and replaced in time.

Engine Heating

Engine overheating, in general, is the body of the cooling water temperature is too high. There are two common reasons for the overheating of the excavator engine, namely, the decline of heat dissipation capacity and the excessive heat load. The reasons for the decline of heat dissipation capacity are:

Poor Heat Dissipation

Radiator Effect

After the radiator is used for too long, the scale inside it is also thickened accordingly. Due to the poor heat transfer capacity of scale, it will not dissipate heat.

Radiator Vent Blocked

When the engine is working, due to the action of the fan, the dust will flow through the radiator with the air. When the dust adheres to the radiator flat tube and heat sink, it not only reduces the air flow section of the radiator, but also causes the thermal conductivity to be too poor due to dust and dirt.

The Fan Belt is Slipping

The size of the cooling intensity of the water cooling system depends on the fan speed, if the fan transmission belt is too loose and slip, it will cause the power transfer efficiency to decline, which not only reduces the fan speed, cooling intensity, but also decreases the pump speed, the displacement is reduced, so that the cooling water flow speed is slow, can not quickly take away the heat, that is, poor heat dissipation.

Influence of Cooling Intensity Regulating Device

Shutters and thermostat are cooling intensity adjustment devices, if the cooling intensity adjustment device failure or improper operation, will lead to excessive engine temperature. The shutter is located in front of the radiator, which is used to adjust the ventilation flow of the radiator, and the ventilation volume is large when the opening is large, and the ventilation volume is small when the opening is small. When the shutters are not closed, the circulation section of the cooled air is smaller, and the result is an increase in engine temperature.

The Thermostat is Damaged

The thermostat is located in the water outlet of the engine, and its function is to adjust the cooling intensity, that is, when the engine temperature is low, the large circulation water is cut off and the small circulation water is connected, so as to reduce the heat dissipation and make the engine temperature rise quickly; When the engine temperature rises to the specified temperature, the thermostat will turn on the large circulation water channel and close the small circulation water channel. If the thermostat is damaged, the large circulation water can not be connected, resulting in poor cooling water circulation, resulting in the heat absorbed by the cooling water can not be sent to the radiator and the engine overheating.

Cooling Water Freezing

When working in winter, the cooling water temperature of the radiator water chamber is very low and easy to freeze. When frozen, the cooling water does not circulate, causing the cooling water temperature to be too high.

Insufficient Cooling Water

Cooling water is the carrier of the heat in the cooling circulation system, that is to say, the heat that is taken away by the carrier of the engine body is taken away by the water, if the coolant of the cooling system is reduced due to leakage or evaporation, the heat in the body will be reduced naturally, so that the heat stored in the engine is too much, that is, the engine is overheating. There are two main reasons for the reduction of cooling water:

Leakage

Cooling system water leakage is more common in water pump seal damage, pipe rupture or joint connection is not tight, radiator damage and water leakage, water release switch damage or close loosely, radiator equipment leakage, etc., will cause cooling system cooling water reduction, resulting in overheating of the engine.

Evaporation

The water in the cooling system evaporates under the influence of temperature, which will also reduce the cooling water in the system. If the replenishment work is not timely, the result is the same as above.

Conclusion

Through the analysis of common faults of excavator engines such as carbon accumulation and overheating, we can see that these problems not only affect the performance of the equipment, but can also lead to serious mechanical damage. Understanding the causes, potential hazards, and effective solutions helps operators and maintenance personnel take timely measures to ensure high efficiency and extend the service life of the device.