QUANCHAI N485D, Руководство по обслуживанию

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ANHUI QUANCHAI ENGINE CO., LTD
The cooling system consists of heat radiating water tank, water pump fan assembly, thermostat components
and connecting rubber pipe. The whole cooling system is a forced circulation closed water-cooled system.
1) Cooling water route: When the diesel engine works, the crankshaft pulley drives the water pump to work
through the belt, presses the cooling water into the water cavity of the engine body to cool the cylinder liner,
the engine body and the cylinder head, and then enters the thermostat. When the outlet water temperature is
lower than 70
℃
, the thermostat is off; then cooling water flows back to the inlet chamber through
corresponding small water pores at the bottom of the cylinder head and the upper plane of the engine body,
and then enters the water pump again to realize small circulation in the engine body. When the outlet water
temperature is higher than 70
℃
to 80
℃
, the thermostat is fully on. At this time, the cooling water flows into
the upper water chamber of the water tank through the thermostat and flows down the radiating pipe to the
lower water chamber. In this process, the cooling water is cooled by the air sucked or discharged by the fan to
realize major circulation.
2) Water pump
Centrifugal water pump is used in this diesel engine.
During use, when the water seal is worn out and the outlet entrance under the water pump body leaks
seriously, the water seal shall be replaced. The outlet entrance is not allowed to be blocked; otherwise water
will enter the bearing, causing the bearing to wear out quickly. If there is too much water leakage and the
bearing makes abnormal noise during operation, consideration shall be given to replacing the bearing.
No.4 calcium-soap grease, also called butter-like grease, shall be filled into the water pump oil filler regularly,
usually once after the diesel engine has been running for about 200 hours. The grease filled shall be no more
than 1/3-1/2 of the bearing cavity. Excessive grease will cause the bearing overheat.
3) The thermostat is of corrugated-pipe single-valve type and is installed in the thermostat shell at the water
outlet at the front end of the cylinder head. It contains liquid sensitive to temperature and automatically
switches on/off the valve. The thermostat is 155B type.
When the initial water temperature in the diesel engine does not reach 70
℃
, the thermostat valve remains off,
and the cooling water begins small circulation in the engine body. When the diesel engine heats up and the
water temperature exceeds 70
℃
, the thermostat valve is on, and the cooling water begins major circulation.
If there is water flowing out of the water outlet pipe when the water temperature does not reach 70
℃
after the
cold-machine diesel engine starts, or if there is no water flowing out of the water outlet pipe when the water
temperature exceeds 70
℃
, it indicates that the thermostat breaks down and shall be disassembled for
inspection. The thermostat can be inspected by means of heating slowly in water. When the water temperature
reaches 70
℃
, the thermostat valve is supposed to start to open, and when the water temperature reaches 85
℃
,
it shall fully open. If the inspection results do not conform to the regulations, the thermostat shall be replaced.
Refrain from removing the thermostat. Too cold cooling water is harmful to the normal operation of the
diesel engine.