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COOLING SYSTEM
7 - 7
COOLING SYSTEM D I A G N O S I S - C O N T I N U E D
Condition and Check
Diagnosis
PRESSURE CAP VENTS TO ATMOSPHERE AND COOLANT
RESERVE TANK. TEMPERATURE GAUGE READING ABOVE
NORMAL BUT NOT HIGH.
(1) Test radiator pressure cap relief pressure. Refer to Radiator
Pressure cap section in this group.
(1) Replace cap if relief pressure is lower than 14 psi.
COOLANT LOSS VISIBLE ON GROUND BELOW VEHICLE, BUT
NO PRESSURE CAP BLOW OFF.
(1) Inspect system for leaks.
(1) Repair as necessary.
COOLANT LOSS PAST PRESSURE CAP TOP SEAL, VISIBLE ON
RADIATOR FILLER NECK.
(1) With normal gauge reading.
(1) a — Pressure cap not installed tightly,
b — Pressure cap top seal leaks,
c — Pressure cap diaphragm bowed,
d — Damaged radiator filler neck,
e — Pressure cap top seal out of position.
(2) With high or low gauge reading on new vehicle.
(2) a — Kinked coolant reserve system hose.
b — Coolant reserve system tank plastic tube plugged,
c — Pressure cap seal out of position.
DETONATION OR PREIGNITION. NOT CAUSED BY IGNITION
OR ENGINE CONDITIONS.
(1) Check engine coolant freeze point. If the tester does not register
a reading or if the reading is below 5 0 ° F
/
inspect ethylene-
glycol/water ratio. A 100 percent solution of ethylene-glycol in
the system causes the engine to run hotter and possibly overheat.
(1) a — Adjust coolant solution to 50/50 water ethylene-glycol
mixture.
b — If 100 percent ethylene-glycol solution is found in system,
clean and flush system before replacing with 50/50 mixture
of ethylene-glycol and water.
COOLING SYSTEM HOSES COLLAPSE ON COOLDOWN.
(1) Inspect pressure cap vent valve.
(1) a — Gasket swell can prevent valve from opening,
b — Replace pressure cap.
(2) Coolant reserve tank hose plugged or kinked.
(2) Repair as necessary.
(3) Inside of pressure cap plugged.
(3) Clean cap or replace if necessary.
COOUNG SYSTEM SUSPECTED AS CAUSE OF INADEQUATE
AIR CONDITIONING SYSTEM PERFORMANCE.
(1) Inspect for plugged radiator and/or condenser.
(1) Clean with low pressure water from fan side.
(2) Inspect for missing air seals in the recirculating air path.
(2) Repair as necessary.
EXCESSIVE FAN NOISE
(1) Inspect for loose or bent fan blades.
(1) Replace fan.
(2) Inspect clearance between fan and adjacent part.
(2) Repair or replace as necessary.
(3) Inspect radiator and condenser for incoming air obstructions.
(3) Clean air path with low pressure water from fan side.
(4) Inspect viscous fan drive.
(4) Replace if viscous drive does not operate properly.
HEAT ODOR
(1) Was temperature gauge reading high?
(1) If YES, refer to GAUGE READING HIGH. If NO, refer to steps
2, 3, and 4.
(2) Are all heat shields in place?
(2) If YES, refer to steps 3 and 4. If NO, repair as required.
(3) If the air side of the heat exchanger plugged?
(3) Clean as necessary.
(4) Engine running rich causing catalytic converter to overheat.
(4) Repair as necessary.
POOR DRIVEABILITY. SUSPECT THERMOSTAT FAILED IN OPEN
POSITION.
(1) Check On-Board Diagnostics. Is code 17 set in memory?
(1) If YES, replace thermostat. If NO, refer to the appropriate
Driveability Manual.
J9007-59
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