Engine Cooling System Trouble In General - Subaru IMPREZA 2004 Service Manual

COOLING

12.Engine Cooling System Trouble in General

A: INSPECTION
Trouble
a. Insufficient engine coolant
b. Loose timing belt
c. Oil on timing belt
d. Malfunction of thermostat
e. Malfunction of water pump
f. Clogged engine coolant passage
g. Improper ignition timing
h. Clogged or leaking radiator
Over-heating
i. Improper engine oil in engine coolant
j. Air/fuel mixture ratio too lean
k. Excessive back pressure in exhaust system
l. Insufficient clearance between piston and cylinder
m. Slipping clutch
n. Dragging brake
o. Defective thermostat
p. Malfunction of radiator fan
a. Atmospheric temperature extremely low
Over-cooling
b. Defective thermostat
a. Loosened or damaged connecting units on hoses
b. Leakage from water pump
c. Leakage from water pipe
Engine coolant
d. Leakage around cylinder head gasket
leaks
e. Damaged or cracked cylinder head and crankcase Repair or replace.
f. Damaged or cracked thermostat case
g. Leakage from radiator
a. Defective timing belt
b. Defective radiator fan
Noise
c. Defective water pump bearing
d. Defective water pump mechanical seal
Engine Cooling System Trouble in General
Possible cause
CO(H4SO)-26
Corrective action
Replenish the engine coolant, inspect for leakage, and
repair.
Repair or replace the timing belt tensioner.
Replace.
Replace.
Replace.
Clean.
Inspect and repair the ignition control system.
<Ref. to EN(H4SO)(diag)-2, Basic Diagnostic Proce-
dure.> or <Ref. to EN(H4SOw/oOBD)(diag)-2, Basic
Diagnostic Procedure.>
Clean or repair, or replace.
Replace the engine coolant.
Inspect and repair the fuel injection system.
<Ref. to EN(H4SO)(diag)-2, Basic Diagnostic Proce-
dure.> or <Ref. to EN(H4SOw/oOBD)(diag)-2, Basic
Diagnostic Procedure.>
Clean or replace.
Adjust or replace.
Repair or replace.
Adjust.
Replace.
Inspect the radiator fan relay, engine coolant tempera-
ture sensor or radiator motor and replace there.
Partly cover the radiator front area.
Replace.
Repair or replace.
Replace.
Repair or replace.
Retighten the cylinder head bolts or replace gasket.
Repair or replace.
Repair or replace.
Replace.
Replace.
Replace the water pump.
Replace the water pump.