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
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
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.