Cooling System Diagnosis - Diesel Engine - Jeep 200 Cherokee Service Manual

7 - 8 COOLING SYSTEM
DIAGNOSIS AND TESTING
PRELIMINARY CHECKS
ENGINE COOLING SYSTEM OVERHEATING
Establish what driving conditions caused the com-
plaint. Abnormal loads on the cooling system such as
the following may be the cause:
(1) PROLONGED IDLE, VERY HIGH AMBIENT
TEMPERATURE, SLIGHT TAIL WIND AT IDLE,
SLOW TRAFFIC, TRAFFIC JAMS, HIGH SPEED
OR STEEP GRADES.
Driving techniques that avoid overheating are:
• Idle with A/C off when temperature gauge is at
end of normal range.
• Increasing engine speed for more air flow is rec-
ommended.
(2) TRAILER TOWING:
Consult Trailer Towing section of owners manual.
Do not exceed limits.
COOLING SYSTEM DIAGNOSIS–DIESEL ENGINE
CONDITION
TEMPERATURE GAUGE
READS LOW
2000 JEEP CHEROKEE
formed on vehicle that may effect cooling system.
This may be:
ing (possibly under filled or air trapped in system).
NOTE: If investigation reveals none of the previous
items as a cause for an engine overheating com-
plaint, refer to following Cooling System Diagnosis
charts.
only. Refer to the group text for information.
POSSIBLE CAUSES
1. Diesel engines, due to their inherent
efficiency are slower to warm up than
gasoline powered engines, and will
operate at lower temperatures when the
vehicle is unloaded.
2. Is the temperature gauge connected to
the temperature gauge coolant sensor on
the engine?
3. Is the temperature gauge operating
OK?
4. Coolant level low in cold ambient
temperatures accompanied with poor
heater performance.
5. Improper operation of internal heater
doors or heater controls.
(3) RECENT SERVICE OR ACCIDENT REPAIR:
Determine if any recent service has been per-
• Engine adjustments (incorrect timing)
• Slipping engine accessory drive belt
• Brakes (possibly dragging)
• Changed parts (incorrect water pump)
• Reconditioned radiator or cooling system refill-
These charts are to be used as a quick-reference
CORRECTION
1. The low gauge reading may be
normal. Refer to thermostats in the
manual text for information. See
Thermostat Diagnosis - Diesel
Engine.
2. Check, the engine temperature
sensor connector in the engine
compartment. Refer to Group 8E.
Repair as necessary.
3. Check gauge operation. Refer to
Group 8E. Repair as necessary.
4. Check coolant level in the
coolant tank. Inspect system for
leaks. Repair leaks as necessary.
Refer to the Coolant section of the
manual text for WARNINGS and
precautions before removing the
pressure cap.
5. Inspect heater and repair as
necessary. Refer to Group 24,
Heating and Air Conditioning for
procedures.
XJ