Daewoo Nubira. Manual - part 137

1D – 2

I

ENGINE COOLING

DAEWOO V–121 BL4

SPECIFICATIONS

CAPACITY

Application

Description

Coolant in the Cooling System

7.0L (1.86 gal) for automatic transaxle
7.0L (1.86 gal) for manual transaxle

FASTENER TIGHTENING SPECIFICATIONS

Application

N

S

m

Lb–Ft

Lb–In

Coolant Pump Mounting Bolts

20

15

–

Engine Coolant Temperature Sensor

10

–

89

Fan Assembly Mounting Bolts

4

–

35

Fan Motor Nut

3.2

–

28

Fan Motor Retaining Screws

4

–

35

Radiator Retaining Bolts, Left Upper and Right Upper

4

–

35

Surge Tank Attaching Bolt

4

–

35

Thermostat Housing Mounting Bolts

15

11

–

SPECIAL TOOLS

SPECIAL TOOLS TABLE

KM–471

Adapter

ENGINE COOLING  1D – 3

DAEWOO V–121 BL4

DIAGNOSIS

THERMOSTAT TEST

1.  Remove the thermostat from the vehicle. Refer to

”Thermostat” in this section.

2.  Make sure the valve spring is tight when the ther-

mostat is fully closed. If the spring is not tight, re-
place the thermostat.

3.  Suspend the thermostat and a thermometer in a

pan of 50/50 mixture of ethylene glycol and water.
Do not let the thermostat or the thermometer rest
on the bottom of the pan because the uneven con-
centration of heat on the bottom could result in in-
accurate temperature measurements.

4.  Heat the pan on a burner.
5.  Use the thermometer to measure the temperature

of the heated solution.

6.  The thermostat should begin to open at 87

³

C

(189

³

F) and it should be fully open at 102

³

C

(216

³

F). If it does not open at these temperatures,

replace the thermostat.

SURGE TANK CAP TEST

Tools Required
KM–471 Adapter

The surge tank cap maintains proper pressure, protects
the system from high pressure by opening a pressure
valve, and protects the coolant hoses from collapsing be-
cause of a vacuum.

1.  Wash any sludge from the surge tank cap and the

valve seat of the vacuum pressure valve for the
surge tank cap.

2.  Check for any damage or deformity to the vacuum

pressure valve for the surge tank cap. If any dam-
age or deformity is found, replace the cap.

3.  Install a suitable cooling system pressure tester to

the cap using the adapter KM–471.

4.  Pull the vacuum pressure valve open. If the surge

tank cap does not seal properly, replace the surge
tank cap.

5.  Pressurize the cap to 90 to 120 kPa (13.1 to 17.4

psi).

6.  Wait 10 seconds and check the pressure held by

the tank cap tester.

7.  If the pressure held by the cooling system pressure

tester falls below 80 kPa (11.6 psi), replace the
surge tank cap.

1D – 4

I

ENGINE COOLING

DAEWOO V–121 BL4

COOLING SYSTEM DIAGNOSIS

Engine Overheats

Checks

Action

Check for a loss of the coolant.

Add the coolant.

Check for a weak coolant solution.

Confirm that the coolant solution is a 50/50 mixture of eth-
ylene glycol and water.

Check the front of the radiator for any dirt, leaves, or in-
sects.

Clean the front of the radiator.

Check for leakage from the hoses, the coolant pump, the
heater, the thermostat housing, the radiator, the core
plugs, or the head gasket.

Replace any damaged components.

Check for a faulty thermostat.

Replace a damaged thermostat.

Check for retarded ignition timing.

Perform an PCM/ECM code diagnosis. Confirm the integ-
rity of the timing belt.

Check for an improperly operating electric cooling fan.

Replace the electric cooling fan.

Check for radiator hoses that are plugged or rotted.

Replace any damaged radiator hoses.

Check for a faulty water pump.

Replace the faulty water pump.

Check for a faulty surge tank cap.

Replace the faulty surge tank cap.

Check for a cylinder head or an engine block that is
cracked or plugged.

Repair the damaged cylinder head or the damaged engine
block.

Loss of Coolant

Checks

Action

Check for a leak in the radiator.

Replace the damaged radiator.

Check for a leak in the following locations:

S

 Surge 

tank.

S

 Hose.

Replace the following parts, as needed:

S

 Surge 

tank.

S

 Hose

Check for loose or damaged radiator hoses, heater hoses,
and connections.

Reseat the hoses.
Replace the hoses or the clamps.

Check for leaks in the coolant pump seal.

Replace the coolant pump seal.

Check for leaks in the coolant pump gasket.

 Replace the coolant pump gasket.

Check for an improper cylinder head torque.

Tighten the cylinder head bolts to specifications.
Replace the cylinder head gasket, if needed.

Check for leaks in the following locations:

S

 Intake 

manifold.

S

  Cylinder head gasket.

S

 Cylinder 

block 

plug.

S

 Heater 

core.

S

  Radiator drain plug.

Repair or replace any components, as needed, to correct
the leak.

Engine Fails to Reach Normal Operating Temperature or Cool Air

from the Heater

Checks

Action

Check to determine if the thermostat is stuck open or is the
wrong type of thermostat.

Install a new thermostat of the correct type and heat range.

Check the coolant level to determine if it is below the MIN
mark on the surge tank.

Add sufficient coolant to raise the fluid to the specified
mark on the surge tank.

ENGINE COOLING  1D – 5

DAEWOO V–121 BL4

COMPONENT LOCATOR

RADIATOR/FAN

1.  Holder Transmission Fluid Pipe (Automatic Trans-

mission Only)

2.  Upper Radiator Bumper
3. Radiator 

Bracket

4. Bolts
5. Radiator
6. Radiator 

Bumper

7. Spring 

Clamp

8.  Upper Radiator Hose
9. Bolts
10.  Auxiliary Cooling Fan (Air Conditioning Only)
11. Drain Cock
12. Main Cooling Fan