Infiniti QX4 (R50). Manual

Overheating Cause Analysis

NBLC0029

Symptom

Check items

Cooling sys-
tem parts
malfunction

Poor heat transfer

Water pump malfunction

Worn or loose drive belt

—

Thermostat stuck closed

—

Damaged fins

Dust contamination or
paper clogging

Mechanical damage

Clogged radiator cooling
tube

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

Reduced air flow

Cooling fan does not oper-
ate

—

High resistance to fan rota-
tion

Damaged fan blades

Damaged radiator shroud

—

Improper coolant mixture
ratio

—

Poor coolant quality

—

Insufficient coolant

Coolant leaks

Cooling hose

Loose clamp

Cracked hose

Water pump

Poor sealing

Radiator cap

Loose

Poor sealing

Radiator

O-ring for damage, dete-
rioration or improper fit-
ting

Cracked radiator tank

Cracked radiator core

Reservoir tank

Cracked reservoir tank

Overflowing reservoir tank

Exhaust gas leaks into
cooling system

Cylinder head deteriora-
tion

Cylinder head gasket
deterioration

ENGINE COOLING SYSTEM

Overheating Cause Analysis

LC-24

Symptom

Check items

Except cool-
ing system
parts mal-
function

—

Overload on engine

Abusive driving

High engine rpm under
no load

Driving in low gear for
extended time

Driving at extremely high
speed

Powertrain system malfunc-
tion

—

Installed improper size
wheels and tires

Dragging brakes

Improper ignition timing

Blocked or restricted air
flow

Blocked bumper

—

Blocked radiator grille

Installed car brassiere

Mud contamination or
paper clogging

Blocked radiator

—

Blocked condenser

—

Installed large fog lamp

Service Data and Specifications (SDS)

THERMOSTAT

NBLC0030

Valve opening temperature

76.5°C (170°F)

Valve lift

More than 8.6 mm/90°C (0.339 in/194°F)

WATER CONTROL VALVE

NBLC0035

Valve opening temperature

95°C (203°F)

Valve lift

More than 8.0 mm/108°C (0.315 in/226°F)

RADIATOR

NBLC0031

Unit: kPa (kg/cm

, psi)

Cap relief pressure

Standard

78 - 98 (0.8 - 1.0, 11 - 14)

Limit

59 - 98 (0.6 - 1.0, 9 - 14)

Leakage test pressure

157 (1.6, 23)

IDX

ENGINE COOLING SYSTEM

Overheating Cause Analysis (Cont’d)

LC-25

MAINTENANCE

SECTION

CONTENTS

PRECAUTIONS ...............................................................2

Supplemental Restraint System (SRS)

SEAT BELT PRE-TENSIONER

″

...............2

PREPARATION ...............................................................3

Special Service Tool ....................................................3
Commercial Service Tool.............................................3

GENERAL MAINTENANCE ............................................4
PERIODIC MAINTENANCE ............................................6

Schedule 1...................................................................7

EMISSION CONTROL SYSTEM MAINTENANCE

.........7

CHASSIS AND BODY MAINTENANCE

........................8

Schedule 2...................................................................9

EMISSION CONTROL SYSTEM MAINTENANCE

.........9

CHASSIS AND BODY MAINTENANCE

......................10

Fluids and Lubricants ................................................ 11
SAE Viscosity Number ..............................................12

GASOLINE ENGINE OIL

..........................................12

GEAR OIL

...............................................................12

Anti-freeze Coolant Mixture Ratio .............................12

ENGINE MAINTENANCE ..............................................13

Checking Drive Belts .................................................13
Changing Engine Coolant..........................................14

-DRAINING ENGINE COOLANT-

..............................14

-REFILLING ENGINE COOLANT-

..............................15

-FLUSHING COOLING SYSTEM-

..............................16

Checking Fuel Lines ..................................................16
Changing Fuel Filter ..................................................16

WITH CONSULT-II

..............................................16

WITHOUT CONSULT-II

.......................................17

Changing Air Cleaner Filter .......................................17

VISCOUS PAPER TYPE

...........................................17

Changing Engine Oil..................................................18
Changing Oil Filter.....................................................18
Changing Spark Plugs...............................................19
Checking EVAP Vapor Lines .....................................20

CHASSIS AND BODY MAINTENANCE .......................21

Checking Exhaust System.........................................21
Checking A/T Fluid ....................................................21
Changing A/T Fluid ....................................................21

Checking All-mode 4WD Transfer Fluid ....................22
Changing All-mode 4WD Transfer Fluid....................22
Checking Propeller Shaft...........................................23
Greasing Propeller Shaft ...........................................23
Checking Differential Gear Oil...................................23
Changing Differential Gear Oil ..................................24

LIMITED-SLIP DIFFERENTIAL GEAR

........................24

Balancing Wheels ......................................................24
Tire Rotation ..............................................................24
Checking Brake Fluid Level and Leaks.....................25
Checking Brake Lines and Cables ............................25
Checking Disc Brake .................................................25

ROTOR

...................................................................25

CALIPER

.................................................................25

PAD

........................................................................25

Checking Drum Brake ...............................................26

WHEEL CYLINDER

..................................................26

DRUM

.....................................................................26

LINING