Dodge 2000 DURANGO Service Manual page 216

7 - 14 COOLING SYSTEM
DIAGNOSIS AND TESTING (Continued)
CONDITION
DETONATION OR
PRE-IGNITION (NOT
CAUSED BY IGNITION
SYSTEM). GAUGE MAY
OR MAY NOT BE
READING HIGH
HOSE OR HOSES
COLLAPSE WHILE
ENGINE IS RUNNING
NOISY VISCOUS
FAN/DRIVE
POSSIBLE CAUSES
1. Engine overheating.
2. Freeze point of coolant not correct.
Mixture is too rich or too lean.
1. Vacuum created in cooling system on
engine cool-down is not being relieved
through coolant reserve/overflow
system.
1. Fan blades loose.
2. Fan blades striking a surrounding
object.
3. Air obstructions at radiator or air
conditioning condenser.
4. Thermal viscous fan drive has
defective bearing.
5. A certain amount of fan noise may be
evident on models equipped with a
thermal viscous fan drive. Some of this
noise is normal.
CORRECTION
1. Check reason for overheating and
repair as necessary.
2. Check coolant concentration. Refer to
the Coolant section of this group and
adjust ratio as required.
1. (a) Radiator cap relief valve stuck.
Refer to Radiator Cap in this group.
Replace if necessary
(b) Hose between coolant reserve/
overflow tank and radiator is kinked.
Repair as necessary.
(c) Vent at coolant reserve/overflow tank
is plugged. Clean vent and repair as
necessary.
(d) Reserve/overflow tank is internally
blocked or plugged. Check for blockage
and repair as necessary.
1. Replace fan blade assembly. Refer to
Cooling System Fans in this Group
2. Locate point of fan blade contact and
repair as necessary.
3. Remove obstructions and/or clean
debris or insects from radiator or A/C
condenser.
4. Replace fan drive. Bearing is not
serviceable. Refer to Viscous Fan Drive
in this group.
5. Refer to Viscous Fan Drive in this
group for an explanation of normal fan
noise.
DN