Infiniti FX35, FX50 (S51). Manual - part 446

OVERHEATING CAUSE ANALYSIS

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< SYMPTOM DIAGNOSIS >

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SYMPTOM DIAGNOSIS

OVERHEATING CAUSE ANALYSIS

Troubleshooting Chart

INFOID:0000000005246381

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 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

—

—

—

Improper engine coolant 
mixture ratio

—

—

—

Poor engine coolant quality

—

Engine coolant density

—

Insufficient engine coolant

Engine coolant leakage

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 leakage into 
cooling system

Cylinder head deterioration

Cylinder head gasket deteri-
oration

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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

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

Blocked air flow

Installed large fog lamp

Symptom

Check items

PRECAUTIONS

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< PRECAUTION >

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PRECAUTION

PRECAUTIONS

Precaution for Supplemental Restraint System (SRS) "AIR BAG" and "SEAT BELT 
PRE-TENSIONER"

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The Supplemental Restraint System such as “AIR BAG” and “SEAT BELT PRE-TENSIONER”, used along
with a front seat belt, helps to reduce the risk or severity of injury to the driver and front passenger for certain
types of collision. This system includes seat belt switch inputs and dual stage front air bag modules. The SRS
system uses the seat belt switches to determine the front air bag deployment, and may only deploy one front
air bag, depending on the severity of a collision and whether the front occupants are belted or unbelted.
Information necessary to service the system safely is included in the “SRS AIR BAG” and “SEAT BELT” of this
Service Manual.

WARNING:

• To avoid rendering the SRS inoperative, which could increase the risk of personal injury or death in

the event of a collision which would result in air bag inflation, all maintenance must be performed by
an authorized NISSAN/INFINITI dealer.

• Improper maintenance, including incorrect removal and installation of the SRS, can lead to personal

injury caused by unintentional activation of the system. For removal of Spiral Cable and Air Bag
Module, see the “SRS AIR BAG”.

• Do not use electrical test equipment on any circuit related to the SRS unless instructed to in this

Service Manual. SRS wiring harnesses can be identified by yellow and/or orange harnesses or har-
ness connectors.

PRECAUTIONS WHEN USING POWER TOOLS (AIR OR ELECTRIC) AND HAMMERS

WARNING:

• When working near the Air Bag Diagnosis Sensor Unit or other Air Bag System sensors with the

ignition ON or engine running, DO NOT use air or electric power tools or strike near the sensor(s)
with a hammer. Heavy vibration could activate the sensor(s) and deploy the air bag(s), possibly
causing serious injury.

• When using air or electric power tools or hammers, always switch the ignition OFF, disconnect the

battery, and wait at least 3 minutes before performing any service.

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< PREPARATION >

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PREPARATION

PREPARATION

PREPARATION

Commercial Service Tools

INFOID:0000000005246383

Tool name

Description

Power tool

Loosening bolts and nuts

Radiator cap tester

Checking radiator and radiator cap

Radiator cap tester adapter

Adapting radiator cap tester to radiator cap 
and water inlet filler neck
a: 28 (1.10) dia.
b: 31.4 (1.236) dia.
c: 41.3 (1.626) dia.
Unit: mm (in)

PBIC0190E

PBIC1982E

S-NT564