CONDITION POSSIBLE CAUSES CORRECTION
COOLANT COLOR. 1. Coolant color is not necessarily
an indication of adequate corrosion
or temperature protection. Do not
rely on coolant color for determin-
ing condition of coolant.
1. Check the freeze point of the
coolant (Refer to 7 - COOLING/
ENGINE/COOLANT - DIAGNOSIS
AND TESTING - COOLANT CON-
CENTRATION TESTING). Adjust
the ethylene glycol-to-water ratio as
necessary.
COOLANT LEVEL CHANGES IN
COOLANT BOTTLE. TEMPERA-
TURE GAUGE IS IN NORMAL
RANGE.
1. Level changes are to be
expected as coolant volume fluctu-
ates with engine temperature. The
coolant level will also drop as the
system removes air from a recent
filling.
1. A normal condition. No repair is
necessary.
TEMPERATURE GAUGE INDICATION DIAGNOSIS CHART
CONDITION POSSIBLE CAUSES CORRECTION
TEMPERATURE GAUGE READ-
ING IS INCONSISTENT (FLUCTU-
ATES, CYCLES OR IS ERRATIC).
1. Normal reaction to fan and/or
thermostat cycle (Fig. 1 ), Exam-
ples B and C. During cold weather
operation with the heater blower in
the high position, the gauge read-
ing may drop slightly (Fig. 1 ),
Example D. Fluctuation is also
influenced by outside temperature
and heavy loads (Fig. 1 ), Exam-
ple E.
1. A normal condition. No correc-
tion is necessary.
2. Gauge reading rise when vehi-
cle is brought to a stop after
heavy use (engine still running)
(Fig. 1 ), Example F.
2. A normal condition. No correc-
tion is necessary. Gauge reading
should return to normal range (Fig.
1 ), Example A, after vehicle is
driven.
3. Gauge reading high after
restarting a warmed-up (hot)
engine.
3. A normal condition. No correc-
tion is necessary. The gauge
should return to normal range (Fig.
1 ), Example A, after a few min-
utes of engine operation.
4. Temperature gauge or engine
sending unit sensor defective or
shorted. Also, corroded or loose
wiring in this circuit.
4. Check operation of gauge and
repair if necessary. Refer to
INSTRUMENT PANEL/GAUGES.
ZB ENGINE 7 - 9
ENGINE (Continued)
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