4.1.4. Diagnostics and troubleshooting
Complaints
Possible causes
Corrections
1. Engine
(1) Lack of coolant
(1) Replenish coolant
overheating
(2) Radiator cap pressure valve spring
(2) Replace cap
weakened
(3) Fan belt loosened or broken
(3) Adjust or replace fan belt
(4) Fan belt fouled with oil
(4) Replace fan belt
(5) Thermostat inoperative
(5) Replace thermostat
(6) Water pump defective
(6) Repair or replace
(7) Restrictions in water passages due
(7) Clean radiator and water
to deposit of scales
passages
(8) Injection timing incorrect
(8) Adjust injection timing correctly
(9) Restriction in radiator core
(9) Clean exterior of radiator
(10) Gases leaking into water jacket
(10) Replace cylinder head gasket
due to broken cylinder head gasket
2. Engine
(1) Thermostat inoperative
(1) Replace thermostat
overcooling
(2) Ambient temperature too low
(2) Install radiator curtain
3. Lack of
(1) Radiator leaky
(1) Correct or replace
coolant
(2) Radiator hoses loosely connected
(2) Retighten clamps or replace hoses
or damaged
(3) Radiator cap valve spring weakened (3) Replace cap
(4) Water pump leaky
(4) Repair or replace
(5) Heater hoses loosely connected or
(5) Tighten or replace hoses
broken
(6) Cylinder head gasket leaky
(6) Replace cylinder head gasket
(7) Cylinder head or cylinder block
(7) Replace cylinder head block
cracked
4. Cooling
(1) Water pump bearing defective
(1) Replace bearing
system
(2) Fan loosely fitted or bent
(2) Retighten or replace fan
noisy
(3) Fan out of balance
(3) Replace fan
(4) Fan belt defective
(4) Replace fan belt
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