Diagnostics and testing of the cooling system (Defender 2007+)

Inspection and verification

1. Check the customer complaint.

2. Visually inspect for obvious mechanical and electrical problems.

Visual inspection

Mechanical elements	Electrical equipment
• Coolant leaks • Coolant hoses • Coolant expansion tank • Radiator • Heater radiator • Drive belt • Fan with viscous coupling	• Fuses • Fuse 29, interior • Wiring harnesses • Loose or corroded connector(s) • Cylinder Head Temperature (CHT) Sensor • Engine Oil Temperature (EOT) Sensor

3. If an obvious cause for the problem you identified or the customer described is found, fix it before proceeding with further actions (if possible).

4. Before referring to the symptom chart or DTC index, read all diagnostic trouble codes (DTCs) using an approved diagnostic system or scan tool.

• Clear all DTCs after troubleshooting.

Table of signs of malfunction

Sign	Possible reason	Operation
Loss of coolant	Hoses Hose connections Radiator Water pump Heater radiator Gaskets Cracks in engine castings Cylinder Block Rod Plugs	Perform a visual inspection. If there are no obvious leaks, perform a pressure test using service station equipment. Repair if necessary.
Overheat	Low coolant level/contaminated Thermostat Viscous coupling fan Cylinder Head Temperature (CHT) Sensor Obstructions to air flow through the radiator	Check the coolant level and condition. Perform a pressure test using a service station stand. Repair if necessary. Check the thermostat and perform the necessary repairs. Check the operation of the viscous fan, make sure that the viscous fan rotates freely. Check for obstructions to the air flow through the radiator. Repair if necessary.
The engine does not reach normal temperature	Thermostat Viscous coupling fan Electric fan	Check the operation of the thermostat. Check the operation of the fan with viscous coupling and make sure that the fan with viscous coupling does not stick. Repair if necessary.

The article was copied from a resource www.LRman.ru

For a complete list of diagnostic trouble codes that may be stored in the vehicle, see Section 100-00. For additional information, refer to: How to Use This Manual (100-00 General information, Description and operating principle).