COOLING SYSTEM
COOLING SYSTEM DIAGNOSIS - DIESEL ENGINE
CONDITION
POSSIBLE CAUSES
CORRECTION
TEMPERATUREGAUGE READS
LOW
1. Vehicle is equipped with a
heavy duty cooling system.
1. None. System operating norma-
ly.
2. Temperature gauge not connect-
ed
2. Connect gauge.
3. Temperature gauge connected
but not operating.
3. Check gauge. Refer (Refer to 8
- ELECTRICAL/INSTRUMENT
CLUSTER - DIAGNOSIS AND
TESTING)
4. Coolant level low.
4. Fill cooling system. (Refer to 7 -
COOLING - STANDARD PROCE-
DURE)
TEMPERATURE GAUGE READS
HIGH. COOLANT MAY OR MAY
NOT BE LEAKING FROM SYS-
TEM
1. Vehicle overloaded, high ambi-
ent (outside) temperatures with
A/C turned on, stop and go driving
or prolonged operation at idle
speeds.
1. Temporary condition, repair not
required. Notify customer of vehicle
operation instructions located in
Owners Manual.
2. Temperature gauge not function-
ing correctly.
2. Check gauge. (Refer to 8 -
ELECTRICAL/INSTRUMENT CLUS-
TER - DIAGNOSIS AND TESTING)
3. Air traped in cooling
3. Drain cooling system (Refer to 7
- COOLING - STANDARD PROCE-
DURE) and refill (Refer to 7 -
COOLING - STANDARD PROCE-
DURE)
4. Radiator cap faulty.
4. Replace radiator cap.
5. Plugged A/C or radiator cooling
fins.
5. Clean all debre away from A/C
and radiator cooling fins.
6. Coolant mixture incorrect.
6. Drain cooling system (Refer to 7
- COOLING - STANDARD PROCE-
DURE) refill with correct mixture
(Refer to 7 - COOLING - STAN-
DARD PROCEDURE).
7. Thermostat stuck shut.
7. Replace thermostat.
8. Bug screen or winter front being
used.
8. Remove bug screen or winter
front.
9. Viscous fan drive not operating
properly.
9. Check viscous fan (Refer to 7 -
COOLING/ENGINE/FAN DRIVE
VISCOUS CLUTCH - DIAGNOSIS
AND TESTING)
10. Cylinder head gasket leaking.
10. Check for leaking head gaskets
(Refer to 7 - COOLING - DIAGNO-
SIS AND TESTING).
11. Heater core leaking.
11. Replace heater core.
12. cooling system hoses leaking.
12. Tighten clamps or Replace
hoses.
7 - 2
COOLING
VA