Doosan DE08TS User Manual

DE08TS Diesel Engines Maintenance of Major Components
Thermostat
1. General descriptions and main data
The thermostat maintains a constant temperature of
coolant 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 thermo-
stat valve, the bypass circuit is closed and the water
passage to the radiator is opened so that the coolant
is forced to flow into the radiator.
There are 3 kinds of thermostats according to sur-
rounding and operating conditions. One is named
by 71 °C , 79°C type and the other is 83 °C.
2. Inspecting
a. Check the wax pallet and spring for damage.
b. Put the thermostat in a container of water, then
heat the water slowly and check temperature
with a thermometer. If the valve lift is 0.1 mm
(starting to open) at temperature of 71 °C and 10
mm or more (full open) at temperature of 85 °C,
the thermostat is normal.
3. Replacing thermostat and precautions for han-
dling
a. Precautions for handling
The wax pallet type thermostat does not react as
quickly as bellows type one to a variation of tem-
perature 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 starting off.
b. When draining out or replenishing coolant, do it
slowly so that air is bled sufficiently from the
entire cooling system.
c. Replacing thermostat
If the thermostat is detected defective, replace
with a new one.
EFM2055I
Ruler
Thermometer
Wood plate
WARNING
EAMC002I
T
o ra
di
a
t
or
To bypass
tube
Bypass
valve
From cooling
water pump
70
Item Specifications
Type Wax-pallet type
Open at 71°C
Open wide at 85°C
Valve lift 8mm or more
Item Specifications
Type Centrifugal type
Pump speed 2,000 rpm 2,700 rpm
1. Water pump
Delivery capacity about 190 liter/min about 280 liter/min
Operation pressure 0.5 bar 0.8 bar
Allowable back pressure bellow 0.5 bar
Operating temperature 71°C
2. Thermostat Valve lift 8mm or more (at 85°C)
Operating temperature 79 ~ 94°C
3. Cooling fan and belt
Fan diameter - Number of blades N625mm - 9
Fan belt tension 15mm deflection by thumb
Specification

Doosan DE08TS Specifications

General

Brand	Doosan
Model	DE08TS
Category	Engine
Language	English