Nissan Frontier D40. Manual - part 187

OVERHEATING CAUSE ANALYSIS

CO-9

< FUNCTION DIAGNOSIS >

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OVERHEATING CAUSE ANALYSIS

Troubleshooting Chart

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Symptom

Check items

Cooling sys-
tem parts 
malfunction

Poor heat transfer

Water pump malfunction

Worn or loose drive belt

—

Thermostat and water con-
trol valve stuck closed

Thermostat or water control 
valve

Damaged fins

Dust contamination or pa-
per clogging

Physical damage

Clogged radiator cooling 
tube

Excess foreign material 
(rust, dirt, sand, etc.)

Reduced air flow

Cooling fan does not oper-
ate

Fan assembly

—

High resistance to fan rota-
tion

Damaged fan blades

Damaged radiator shroud

—

Radiator shroud

—

Improper engine coolant 
mixture ratio

—

Engine coolant viscosity

—

Poor engine coolant quality

—

—

Insufficient engine coolant

Engine coolant leaks

Cooling hose

Loose clamp

Cracked hose

Water pump

Poor sealing

Radiator cap

Loose

Poor sealing

Radiator

O-ring for damage, deterio-
ration or improper fitting

Cracked radiator tank

Cracked radiator core

Reservoir tank

Cracked reservoir tank

Overflowing reservoir tank

Exhaust gas leaks into cool-
ing system

Cylinder head deterioration

Cylinder head gasket deteri-
oration

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< FUNCTION DIAGNOSIS >

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OVERHEATING CAUSE ANALYSIS

Except cool-
ing system 
parts mal-
function

—

Overload on engine

Abusive driving

High engine rpm under no 
load

Driving in low gear for ex-
tended time

Driving at extremely high 
speed

Power train system mal-
function

—

Installed improper size 
wheels and tires

Dragging brakes

Improper ignition timing

Blocked or restricted air 
flow

Blocked bumper

Mud contamination or paper 
clogging

—

Blocked radiator grille

Installed car brassiere

Mud contamination or paper 
clogging

Blocked radiator

Blocked air flow

Blocked condenser

Installed large fog lamp

Symptom

Check items

ENGINE COOLANT

CO-11

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ON-VEHICLE MAINTENANCE

ENGINE COOLANT

System Inspection

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WARNING:

• Never remove the radiator cap or reservoir tank cap when the engine is hot. Serious burns could

occur from high pressure fluid escaping from the radiator or reservoir.

• Wrap a thick cloth around the cap. Slowly push down and turn it a quarter turn to allow built-up pres-

sure to escape. Carefully remove the cap by pushing down and turning it all the way.

CHECKING COOLING SYSTEM HOSES

Check hoses for the following:
• Improper attachment
• Leaks
• Cracks
• Damage
• Loose connections
• Chafing
• Deterioration

CHECKING RESERVOIR LEVEL

• Check if the engine coolant reservoir tank level is within MIN to

MAX when the engine is cool.

• Adjust engine coolant level as necessary.

CHECKING COOLING SYSTEM FOR LEAKS

WARNING:

Never remove the radiator cap or reservoir cap when the engine is hot. Serious burns could occur
from high pressure coolant escaping from the radiator or reservoir.
• To check for leakage, apply pressure to the cooling system at the

reservoir filler neck using suitable tool and Tool.

CAUTION:

Higher pressure than specified may cause radiator damage.
NOTE:
In case that engine coolant decreases, replenish cooling system
with engine coolant.

• If any concerns are found, repair or replace damaged parts.

CHECKING RESERVOIR CAP

1.

Inspect the reservoir cap.
• Replace the cap if the metal plunger cannot be seen around the edge of the black rubber gasket.
• Replace the cap if deposits of waxy residue or other foreign material are on the black rubber gasket or

the metal retainer.

NOTE:
Thoroughly wipe out the reservoir filler neck to remove any waxy residue or foreign material.

SMA412B

Tool number

: EG17650301 (J-33984-A)

Testing pressure

: 137 kPa (1.4 kg/cm

2

, 20 psi)

WBIA0568E

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ENGINE COOLANT

2.

Pull the negative-pressure valve to open it and check that it
closes completely when released.
• Check that there is no dirt or damage on the valve seat of the

reservoir cap negative-pressure valve. 

• Check that there are no abnormalities in the opening and clos-

ing conditions of the negative-pressure valve.

3.

Check reservoir cap relief pressure using suitable tool and Tool.

NOTE:
• Apply engine coolant to the cap seal surface. 
• Replace the reservoir cap if there is any damage in the nega-

tive-pressure valve, or if the open-valve pressure is outside of
the limit.

CHECKING RADIATOR CAP

Inspect the radiator cap.
NOTE:
Thoroughly wipe out the radiator filler neck to remove any waxy residue or foreign material.
• Replace the cap if the metal plunger cannot be seen around the edge of the black rubber gasket.
• Replace the cap if deposits of waxy residue or other foreign material are on the black rubber gasket or the

metal retainer.

CHECKING RADIATOR

Check radiator for mud or clogging. If necessary, clean radiator as follows.

CAUTION:

• Be careful not to bend or damage the radiator fins.
• When radiator is cleaned without removal, remove all surrounding parts such as cooling fan shroud

and horns. Then tape the harness and electrical connectors to prevent water from entering.

1.

Apply water by hose to the back side of the radiator core, with the hose pointed vertically downward.

2.

Apply water again to all radiator core surfaces once per minute.

3.

Stop washing if any stains no longer flow out from the radiator.

4.

Blow air into the back side of radiator core, with the air hose pointed vertically downward.
• Use compressed air lower than 490 kPa (5 kg/cm

2

, 71 psi) and keep distance more than 30 cm (11.8 in). 

5.

Blow air again into all the radiator core surfaces once per minute until no water sprays out.

6.

Check for leaks.

Changing Engine Coolant

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WARNING:

• To avoid being scalded, never change the coolant when the engine is hot.
• Wrap a thick cloth around the cap to carefully remove the cap. First, turn the cap a quarter of a turn

to release any built-up pressure, then push down and turn the cap all the way to remove it.

DRAINING ENGINE COOLANT

1.

Turn ignition switch ON and set temperature control lever all the way to HOT position or the highest tem-
perature position. Wait 10 seconds and turn ignition switch OFF.

2.

Remove the engine front under cover. Refer to 

EXT-13, "Removal and Installation"

.

SMA967B

Tool number

: EG17650301 (J-33984-A)

Standard: 98 – 118 kPa (1.0 – 1.2 kg/cm

2

, 14 – 17 psi)

WBIA0570E