Subaru Impreza 2004 - Engine Cooling System Trouble in General

CO(H4SO)-26
COOLING
Engine Cooling System Trouble in General
12.Engine Cooling System Trouble in General
A: INSPECTION
Trouble Possible cause Corrective action
Over-heating
a. Insufficient engine coolant
Replenish the engine coolant, inspect for leakage, and
repair.
b. Loose timing belt Repair or replace the 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 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.>
h. Clogged or leaking radiator Clean or repair, or replace.
i. Improper engine oil in engine coolant Replace the engine coolant.
j. Air/fuel mixture ratio too lean
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.>
k. Excessive back pressure in exhaust system Clean or replace.
l. Insufficient clearance between piston and cylinder Adjust or replace.
m. Slipping clutch Repair or replace.
n. Dragging brake Adjust.
o. Defective thermostat Replace.
p. Malfunction of radiator fan
Inspect the radiator fan relay, engine coolant tempera-
ture sensor or radiator motor and replace there.
Over-cooling
a. Atmospheric temperature extremely low Partly cover the 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 the cylinder head bolts or replace gasket.
e. Damaged or cracked cylinder head and crankcase Repair or replace.
f. Damaged or cracked thermostat case Repair or replace.
g. Leakage from radiator Repair or replace.
Noise
a. Defective timing belt Replace.
b. Defective radiator fan Replace.
c. Defective water pump bearing Replace the water pump.
d. Defective water pump mechanical seal Replace the water pump.