Subaru Impreza 3 / Impreza WRX / Impreza WRX STI. Manual — part 190

CO(w/o STI)-29

Engine Cooling System Trouble in General

COOLING

12.Engine Cooling System Trouble in General

A: INSPECTION

Trouble

Possible cause

Corrective action

Over-heating

a. Insufficient engine coolant

Replenish engine coolant, inspect for leakage,
and repair it if necessary.

b. Loose timing belt

Repair or replace timing belt tensioner.

c. Oil on timing belt

Replace.

d. Malfunction of thermostat

Replace.

e. Malfunction of water pump

Replace.

f. Clogged engine coolant passage

Clean.

g. Improper ignition timing

Inspect and repair ignition control system. <Ref.
to EN(H4DOTC)(diag)-2, PROCEDURE, Basic
Diagnostic Procedure.>

h. Clogged or leaking radiator

Clean, repair or replace.

i. Defective radiator fan

Replace.

j. Improper engine oil in engine coolant

Replace the engine coolant. If ineffective, check,
repair or replace engine components.

k. Air/fuel mixture ratio too lean

Inspect and repair the fuel injection system.
<Ref. to EN(H4DOTC)(diag)-2, PROCEDURE,
Basic Diagnostic Procedure.>

l. Excessive back pressure in exhaust system

Clean or replace.

m. Insufficient clearance between piston and cylinder

Adjust or replace.

n. Slipping clutch

Repair or replace.

o. Dragging brake

Adjust.

p. Defective radiator fan

Inspect the radiator fan relay, engine coolant
temperature sensor or fan motor and replace
them.

Over-cooling

a. Ambient temperature extremely low

Partly cover radiator front area.

b. Defective thermostat

Replace.

Engine coolant
leaks

a. Loosened or damaged connecting units on hoses

Repair or replace.

b. Leakage from water pump

Replace.

c. Leakage from water pipe

Repair or replace.

d. Leakage around cylinder head gasket

Retighten cylinder head bolts or replace cylinder
head gasket.

e. Damaged or cracked cylinder head and cylinder block Repair or replace.
f. Damaged or cracked thermostat cover

Repair or replace.

g. Leakage from radiator

Repair or replace.

Noise

a. Timing belt problem

Replace.

b. Defective radiator fan

Replace.

c. Defective water pump bearing

Replace water pump.

d. Defective water pump mechanical seal

Replace water pump.

CO(w/o STI)-30

Engine Cooling System Trouble in General

COOLING

LUBRICATION

LU(w/o STI)

Page

1.

General Description . . . . . . . . . . . . . . . . . . . . ...2

LU(w/o STI)-2

General Description

LUBRICATION

1. General Description

A: SPECIFICATION

Specifications for models other than STI are includ-

ed in the LU (STI) section. <Ref. to LU(STI)-2, Gen-

eral Description.>