Initial Inspection and Diagnostic Overview
OVERVIEWEstablish what driving condition caused the cooling system complaint. The problem may be caused by an abnormal load on the system such as the following: prolonged idle, very high ambient temperature, slight tail wind at idle, slow traffic speed, traffic jam, high speed, steep grade.
DRIVING TECHNIQUES
To avoid overheating the cooling system:
1. Idle with A/C off when temperature gauge is at end of normal range.
2. Do not increase engine speed for more air flow and coolant flow because the electric motor fan systems are not responsive to engine RPM. The added cooling from higher coolant flow rate is more than offset by increased heat rejection (engine heat added to coolant).
TRAILER TOWING
Consult the owner's manual under Trailer Towing and do not exceed specified limits.
AIR CONDITIONING ADDED ON OR AFTERMARKET
If add-on or aftermarket A/C is involved, maximum cooling components should be installed for the model involved per manufacturer's specifications. Further diagnostic checks should not be required.
VISUAL INSPECTION
If the cooling system problem is not caused by a driving condition, perform a visual inspection to determine if there was a recent service or accident repair, including the following:
^ Loose/damaged water pump drive belt
^ Incorrect cooling system refilling (trapped air or low level)
^ Brakes possibly dragging
^ Damaged hoses
^ Loose/damaged hose clamps
^ Damaged/incorrect engine thermostat
^ Damaged cooling fan motor, fan blade, and fan shroud
^ Damaged head gasket
^ Damaged water pump
^ Damaged radiator
^ Damaged coolant recovery system
^ Damaged heater core
^ Open/shorted electrical circuits
If the visual inspection reveals none of the above as cause for a cooling system complaint, refer to the following diagnostic charts.
Part 1 Of 4:
Part 2 Of 4:
Part 3 Of 4:
Part 4 Of 4:
COOLING SYSTEM DIAGNOSIS CHART
RADIATOR COOLING FAN DIAGNOSIS CHART
Temperature Gauge Indications (Part 1 Of 2):
Temperature Gauge Indications (Part 2 Of 2):
TEMPERATURE GAUGE INDICATION DIAGNOSIS CHART