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Analysis of Construction Engine Overheating

Phenomenon

The engine overheating means the engine temperature exceed the normal max. temperature (80-90℃), even the water in the radiator will be boiling.

The analysis of causes

Engine overheating, generally it is the cooling water temperature in the engine body is too high. And there are two common reasons of engine overheating, which are the recession of heat dissipation capacity and the high thermal load.

1. The reasons of the recession of heat dissipation capacity:

(1) The insufficient cooling water

Cooling water is the heat carrier of cooling circulatory system, which is the heat of the engine taken away by the cooling water. If the coolant in the cooling system reduced due to leaking or evaporating, and the heat need to be taken will reduce, then it will appear excess heat, which is heat overheating. And there are two reasons of reducing cooling water:

a. The cooling system leaked as the water pump and seal was damaged, the tube was broken and the loose connection or the radiator was destroyed and so on. All will cause the reduction of cooling water.

b. The cooling water evaporated by the temperature, it also will reduce the cooling water, if we don’t supply the cooling water timely, the consequence will be the same as above.

(2) The poor dissipation

a. The influences of radiator

After years of radiator used, its internal fouling were also be thicken, due to the heat transfer ability is poor, and the heat dissipation will be poor.

b. The radiator vent be plugged

When the engine is working, as a result of the action of fan, the dust will through the radiator along with the air. If the dust adhere to the flat tube of the radiator and the cooling fin, it not only reduce the radiator air flow section, as well as due to the dust and the fouling, which lead to the poor capacity of heat transmission, then will result in the bad heat dissipation.

c. Fan Belt Slipping

The cooling intensity of cooling system depends on the fan speed, if the belt slipped by the loose fan drive, it will cause the loss of power transfer efficiency, which is not only bring down the fan speed, reduce the cooling intensity, and the water pump speed also fell, and it made the cooling water flow slow and cannot take away the heat, namely the heat dissipation is poor.

d. The influences of the regulate device of cooling intensity

The shutters and the thermostat are the regulate device of the cooling system, if there are some problems with the regulate device or improper operation, they will lead to the engine temperature is too high.

The shutters equipped before the radiator is used to adjust the radiator air flow, the opening is large the air flow is the same as it, vice versa. When the shutters aren’t opened, the air flow area will be smaller, and then will rise the engine temperature.

e. The thermostat be damaged

The thermostat is located in the outlet of the engine, its role is to adjust cooling intensity, namely the engine at low temperature, it truncates the circulation waterway to connect with the minor cycle waterway, to reduce the heat dissipation capacity and make the temperature rising; the engine temperature rising to the specified temperature, thermostat connected with the circulation waterway and closed minor cycle waterway. If the thermostat damaged, it cannot connected with the circulation waterway, it will cause poor water cooling cycle, and which leads to the heat absorbed by the cooling water cannot bring into the radiator, then the engine temperature will be more high.

f. The cooling water frozen

When the engine working in the winter, the cooling water temperature will be very low and it easy to freezing, once the cooling water is freezing, it will not circulate, thus the cooling water temperature is too high.

2. The reasons of high thermal load

(1) The diesel engine working roughly

The diesel engine working roughly as firing time delayed, inject more fuel and combust well-prepared, once the fire flame, it will spread everywhere rapidly, the pressure rate increase, and then the roughly working.

(2) Injection time is too late

Fuel injection advance angel is too small; most of combustion work are moved to the expansion process. The top volume of piston increase, the contact area of flame and cylinder wall will be also increase, the heat absorption also increase, thus reduce the utilization rate of thermal efficiency, and the exhaust temperature rise and the incoming heat of the cooling water will increase.

(3) Carbon deposit

There are too much carbon deposit in the engine’s combustion chamber will accumulate heat, this is also the reason of cooling water temperature is too high.

(4) Too tight engine assembly

For the engine is too tight, the friction resistance is very big, generate heat and increases, when the heat pass down to the cooling system, it made the cooling system high load, and the engine temperature is too high.

(5) Improper operation

Engineering engine often work under heavy load, coupled with the high environment temperature, it is not only add the heat load to cooling system, and as high environment temperature, the cooling system of heat exchange rate become bad, which make the engine temperature is too high.