MAINTENANCE OF MAJOR COMPONENTS(A)
1. Engine won’t start
6.2. Cooling System 1. General information
This engine is water-cooling type. Heat from the combustion chamber and engine oil heat are cooled down by coolant and radiated to the outside, resulting in the normal operation of the engine.
Looking into the cooling system, the water pumped up by the water pump circulates around the oil cooler through the water pipe to absorb the oil heat, and then flows through the water jacket of the cylinder block and water passage of the cylinder head to absorb the heat of the combustion chamber.
The water absorbing the oil heat and combustion chamber heat goes on to the thermostat through the water pipe, and circulates to the water pump if water temperature is lower than the valve opening temperature on the thermostat, while circulating to the radiator at water tem-perature higher than the valve opening temtem-perature. At the radiator, the heat absorbed in the coolant is radiated to cool down and the coolant recirculates to the water pump.
6.2.2. Specification
MAINTENANCE OF MAJOR COMPONENTS
Radiator
Thermostat Water pipe
Cylinder head
Cylinder block
Oil cooler Water pump
Air compressor
EQM4001I
Description Specification
1. Water pump Type Centrifugal type
Delivery About 350 liter/min
Pumping speed 2,100 rpm
Pumping back pressure 760 mmHg 2. Thermostat Operating temperature 71 ~ 85°C 3. Cooling fan and belt Fan diameter - Number of blades l812.8 mm - 9
Fan belt tension 15 mm / deflection by thumb
6.2.3. Water pump
•
Loosen the bolt (14) to disassemble the housing cover (13).•
Heat the impeller (5) slightly, then remove it using a puller jig.•
Remove the mechanical seal.•
Remove the shaft and bearing assembly from the housing.•
With a press, remove the spline shaft and bearing.•
Reverse the disassembly sequence for reassembly operation.•
Replace the oil seal (6) with a new one at reassembly.•
To reassemble the impeller, maintain a constant gap (0.3 ~ 0.6 mm) between the impeller and pump housing using a feeler gauge.<Construction of water pump>
1. Water pump housing 6. Oil seal 11. Spline shaft
2. Pipe 7. Ball bearing 12. Gasket
3. Shaft 8. Space 13. Housing cover
4. Mechanical seal 9. Ball bearing 14. Bolt
5. Impeller 10. Stopper ring 15. Pipe
간극 0.3-0.6mm
PAR LATEX COATING
3
5 4 6 7 12 14
8 9 10
15 11
1 552
13
EQM8001I Thickness
EQM8001I
6.2.4. Thermostat
•
General descriptions and main data The thermostat maintains a constant temperature of coolant (90 ~ 95 °C) and improves thermal efficiency of the engine by preventing heat loss.Namely, when the temperature of coolant is low, the thermostat valve is closed to make the coolant bypass to directly enter the water pump; when the coolant temperature rises to open wide the thermostat valve, the bypass circuit is closed and the water pas-sage to the radiator is opened so that the coolant is forced to flow into the radiator.
NOTE :
There are 2 kinds of thermostats according to surrounding and operating conditions.
One is named by 71 °C type and the other is 83 °C.
•
Inspecting(1) Check the wax pallet and spring for damage.
(2) Put the thermostat in a container of water, then heat the water slow-ly and check temperature with a thermometer. If the valve lift is 0.1 mm (starting to open) at tempera-ture of 83 °C and 8 mm or more (opening wide) at temperature of 95 °C, the thermostat is normal.
MAINTENANCE OF MAJOR COMPONENTS
EAMC002I
In moderate climates In tropical climates
Type Wax-pallet type Wax-pallet type
Open at 83 °C 71 °C
Open wide at 95 °C 85 °C
Valve lift 8 mm or more Truck : 8 mm or more
•
Replacing thermostat and precautions for handling (1) Precautions for handlingThe wax pallet type thermostat does not react as quickly as bellows type one to a vari-ation of temperature of coolant. Such relatively slow reaction is mainly due to the large heat capacity of the wax pellet type thermostat. Therefore, to avoid a sharp rise of coolant temperature, it is essential to idle the engine sufficiently before running it. In cold weather, do not run the engine at overload or overspeed it immediately after engine start-ing.
(2) When draining out or replenishing coolant, do it slowly so that air is bled sufficiently from the entire cooling system.
(3) Replacing thermostat
If the thermostat is detected defective, retrace with a new one.
6.2.5. Diagnostics and troubleshooting
MAINTENANCE OF MAJOR COMPONENTS
Complaints Possible causes Corrections
1. Engine overheating
•
Lack of coolant•
Replenish coolant•
Radiator cap pressure valve•
Replace cap spring weakened•
Fan belt loosened or broken•
Adjust or replace fan belt•
Fan belt fouled with oil•
Replace fan belt•
Thermostat inoperative•
Replace thermostat•
Water pump defective•
Repair or replace•
Restrictions in water passages•
Clean radiator and water due to deposit of scales passages•
Injection timing incorrect•
Adjust injection timing correctly•
Restriction in radiator core•
Clean exterior of radiator•
Gases leaking into water jacket•
Replace cylinder head gasket due to broken cylinder headgasket
2. Engine overcooling
•
Thermostat inoperative•
Replace thermostat•
Ambient temperature too low•
Install radiator curtain 3. Lack of coolant•
Radiator leaky•
Correct or replace•
Radiator hoses loosely•
Retighten clamps or replaceconnected or damaged hoses
•
Radiator cap valve spring•
Replace cap weakened•
Water pump leaky•
Repair or replace•
Heater hoses loosely•
Tighten or replace hoses connected or broken•
Cylinder head gasket leaky•
Replace cylinder head gasket•
Cylinder head or cylinder block•
Replace cylinder head or block cracked4. Cooling system noisy