Subaru Crosstrek Service Manual: Engine cooling system trouble in general Inspection

Over-heating

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. Basic Diagnostic Procedure">

f. Clogged or leaking radiator

Clean, repair or replace.

g. Defective radiator cap

Replace.

h. Improper engine oil in engine coolant

Replace the engine coolant. If ineffective, check, repair or replace engine components.

i. Air/fuel mixture ratio too lean

Inspect and repair the fuel injection system. Basic Diagnostic Procedure">

j. Excessive back pressure in exhaust system

Clean or replace.

k. Insufficient clearance between piston and cylinder

Adjust or replace.

l. Slipping clutch

Repair or replace.

m. Dragging brake

Adjust.

n. Malfunction of 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. Defective radiator fan

Replace.

b. Defective water pump bearing

Replace water pump.

c. Defective water pump mechanical seal

Replace water pump.