Diagnostic Strategies

PRELIMINARY CHECKS

ENGINE COOLING SYSTEM OVERHEATING
Establish what driving conditions caused the complaint. Abnormal loads on the cooling system such as the following may be the cause:
^ 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 recommended.

TRAILER TOWING:
Consult Trailer Towing section of owners manual. Do not exceed limits.

RECENT SERVICE OR ACCIDENT REPAIR:
Determine if any recent service has been performed on vehicle that may affect the cooling system. This may be:
^ Engine adjustments (incorrect timing)
^ Slipping engine accessory drive belt(s)
^ Brakes (possibly dragging)
^ Changed parts. Incorrect water pump or pump rotating in wrong direction due to belt not correctly routed
^ Reconditioned radiator or cooling system refilling (possibly under filled or air trapped in system).
^ Service to electrically controlled viscous fan clutch

NOTE: If investigation reveals none of the previous items as a cause for an engine overheating complaint, refer to COOLING SYSTEM DIAGNOSIS CHART. Diagnosis By Symptom

These charts are to be used as a quick-reference only. Refer to COOLING SYSTEM DIAGNOSIS CHART. Diagnosis By Symptom