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Start engine and accelerate rapidly three times, to approximately 3000 rpm while observing coolant. If internal PRELIMINARY CHECKS ENGINE COOLING SYSTEM OVERHEATING Establish what driving conditions caused the complaint. Abnormal loads on the cooling system such as the following • 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 effect 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). Note: If investigation reveals none of the previous items as a cause for an engine overheating complaint, These charts are to be used as a quick-reference only. Refer to COOLING SYSTEM DIAGNOSIS CHART HB COOLING 7 - 7 |