Daewoo Nubira. Manual — part 138

1D – 6

I

ENGINE COOLING

DAEWOO V–121 BL4

COOLANT PUMP/THERMOSTAT (2.0L DOHC)

1. O–Ring

Seal

2. Thermostat
3. Thermostat

Housing

4. Bolt

5. Bolt
6. Coolant

Pump

7. Ring

Seal

ENGINE COOLING 1D – 7

DAEWOO V–121 BL4

MAINTENANCE AND REPAIR

On–Vehicle Service

DRAINING AND REFILLING THE
COOLING SYSTEM

CAUTION : Do not remove the surge tank cap while
the engine and the radiator are hot. Scalding fluid and
steam may be blown out under pressure.

1. Place a pan below the vehicle to catch the draining

coolant.

2. Remove the surge tank cap.
3. Unplug the drain plug.
CAUTION : Dispose of the used coolant to a used
coolant holding tank to be picked up with the used oil
for disposal. Never pour the used coolant down the
drain. Ethylene glycol antifreeze is an extremely toxic
chemical. Disposing of it into the sewer system or the
ground water can contaminate the local environment.

4. Catch the escaping fluid in a drain pan.
5. Remove all sludge and dirt from inside the surge

tank. Refer to ”Surge Tank” in this section.

6. Plug the drain cock.
7. Add the clean water to the surge tank.
8. Fill the tank slowly so that the upper reservoir hose

remains above the water line. This allows the air
inside the cooling system to escape.

9. Start the engine.
10. Run the engine until the thermostat opens. When

both radiator hoses are hot to the touch, the ther-
mostat is open.

11. Stop the engine.
12. Repeat Steps 1 through 9 until the drained water is

clear and free of coolant and rust.

Notice : Never use an antifreeze mixture more concen-
trated than 60 percent antifreeze to 40 percent water. The
solution freezing point increases above this concentration.

13. Fill the cooling system through the surge tank with

a mixture of ethylene glycol antifreeze and water.
The mixture must be at least 50 percent antifreeze,
and not more than 60 percent antifreeze.

14. Fill the surge tank to the specified MAX mark on

the outside of the tank.

1D – 8

I

ENGINE COOLING

DAEWOO V–121 BL4

THERMOSTAT

Removal Procedure

CAUTION : To prevent personal injury, do not remove
the surge tank cap while the engine and the radiator
are hot because the heat causes the system to remain
under pressure. Scalding fluid and steam may be
blown out under pressure.

1. Drain the coolant. Refer to ”Draining and Refilling

the Cooling System” in this section.

2. Loosen the hose clamp on the upper radiator hose

at the thermostat housing.

3. Disconnect the upper radiator hose from the ther-

mostat housing.

4. Remove the mounting bolts that hold the thermo-

stat housing to the cylinder head.

5. Remove the thermostat housing from the cylinder

head.

6. Remove the O–ring seal from the thermostat hous-

ing.

7. Remove the thermostat from the thermostat hous-

ing by pressing the thermostat mounting flange
downward and then rotating the flange clockwise.

8. Inspect the valve seat for foreign matter that could

prevent the valve from sealing properly.

9. Inspect the thermostat for proper operation. Refer

to ”Thermostat Test” in this section.

10. Clean the thermostat housing and the cylinder head

mating surfaces.

ENGINE COOLING 1D – 9

DAEWOO V–121 BL4

Installation Procedure

1. Install the thermostat into the thermostat housing

by pressing the thermostat mounting flange down-
ward and then rotating the flange counterclockwise.
Rotate the thermostat mounting flange until it is
seated in the thermostat housing recesses.

2. Coat the sealing surface of a new O–ring seal with

Lubriplate

±

.

3. Install a new O–ring seal into the recess in the ther-

mostat housing.

4. Install the thermostat housing to the cylinder head.
5. Secure the thermostat housing to the cylinder head

with the mounting bolts.

Tighten

Tighten the thermostat housing mounting bolts (2.0L
DOHC) to 15 N

S

m (11 lb–ft).

6. Connect the upper radiator hose to the thermostat

housing.

7. Secure the upper radiator hose to the thermostat

housing with a hose clamp.

8. Refill the engine cooling system. Refer to ”Draining

and Refilling the Cooling System” in this section.