Subaru Legacy IV (2008 year). Manual - part 500
CO(H6DO)-26
Engine Cooling System Trouble in General
COOLING
12.Engine Cooling System Trouble in General
A: INSPECTION
Trouble
Possible cause
Corrective action
Overheating
a. Insufficient engine coolant
Replenish engine coolant, inspect for leakage, and
repair it if necessary.
b. Defective thermostat
Replace.
c. Malfunction of water pump
Replace.
d. Clogged engine coolant passage
Clean.
e. Improper ignition timing
Inspect and repair ignition control system. <Ref. to
EN(H6DO)(diag)-2, PROCEDURE, Basic Diagnostic
Procedure.>
f. Clogged or leaking radiator
Clean, repair or replace.
g. Improper engine oil in engine coolant
Replace engine coolant. If ineffective, check, repair or
replace engine components.
h. Air/fuel mixture ratio too lean
Inspect and repair the fuel injection system. <Ref. to
EN(H6DO)(diag)-2, PROCEDURE, Basic Diagnostic
Procedure.>
i. Excessive back pressure in exhaust system
Clean or replace.
j. Insufficient clearance between piston and cylinder
Adjust or replace.
k. Dragging brake
Adjust.
l. Defective radiator fan
Inspect the radiator fan relay, engine coolant tempera-
ture 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 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. Defective radiator fan
Replace.
b. Defective water pump bearing
Replace water pump.
c. Mechanical water pump malfunction
Replace water pump.