Subaru Legacy 2005 Service Manual page 1210

COOLING
12.Engine Cooling System Trouble in General
A: INSPECTION
Trouble
a. Insufficient engine coolant
b. Loose timing belt
c. Oil on drive belt
d. Malfunction of thermostat
e. Malfunction of water pump
f. Clogged engine coolant passage
g. Improper ignition timing
Overheating h. Clogged or leaking radiator
i. Engine oil mixed 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 radiator fan
a. Ambient 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 Correct or replace.
f. Damaged or cracked thermostat case
g. Leakage from radiator
a. Defective drive 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(H4DOTC)-32
Corrective action
Replenish engine coolant, inspect for leakage, and
repair it if necessary.
Repair or replace timing belt tensioner.
Replace.
Replace.
Replace.
Clean.
Inspect and repair ignition control system. <Ref. to
EN(H4DOTC)(diag)-2, PROCEDURE, Basic Diagnostic
Procedure.>
Clean, repair or replace.
Check, repair or replace the parts around engine.
Inspect and repair the fuel injection system. <Ref. to
EN(H4DOTC)(diag)-2, PROCEDURE, Basic Diagnostic
Procedure.>
Clean or replace.
Adjust or replace.
Correct or replace.
Adjust.
Inspect radiator fan relay, engine coolant temperature
sensor or fan motor and replace them.
Partly cover radiator front area.
Replace.
Correct or replace.
Replace.
Correct or replace.
Retighten cylinder head bolts or replace gasket.
Correct or replace.
Correct or replace.
Replace.
Replace.
Replace water pump.
Replace water pump.