QuestionJohn, I have a overheating issue. I replaces the thermostat and did not resolve the problem. It appears I have good flow with the waterpump. I noticed it tends to overheat only when the a/c is on. I see the a/c fan comes on but the other fan does not turn on, even when the temp gauge gets high. I checked the fuse under the dash and it was OK. Any other way to test this fan? is replacement difficult?
AnswerHi Jay,
could be faulted AC fan.
Here's some troubleshooting help from the LR techsheets:
ENGINE OVERHEATING
Before conducting any cooling system diagnosis: See Description and operation, Engine Cooling
1. Is coolant level correct?
NO - Allow engine to cool, top up level to
expansion tank seam.
YES - Continue.
2. Is drive belt tension correct?
NO - See ENGINE, Repair, Compressor Drive Belt
YES - Continue.
3. Is coolant in radiator frozen?
YES - Slowly thaw and drain system. See Adjustment, Coolant
NO - Continue.
4. Is air flow through radiator restricted or blocked?
YES - Apply air pressure from engine side of radiator to clear obstruction.
NO - Continue.
5. Are there any external leaks, from water pump, engine gaskets, fast idle thermostat or the heater unit?
YES - Investigate and rectify. See Adjustment, Coolant
NO - Continue.
6. Are fan blades fitted correct way round, concave side towards engine?
NO - Rectify.
YES - Continue
7. Is viscous unit operating correctly? See Description and operation, Viscous Fan
NO - Renew. See Repair, Viscous Coupling, Fan Blades, Pulley and Fan Cowl
YES - Carry out a pressure test on radiator cap and system. Check thermostat type, operation and correct fitting. See Repair, Thermostat If pressure test leads you to suspect coolant leakage across gaskets, go to check 10,
otherwise: Continue.
8. Are the air conditioning fans operating correctly?
See Electrical Trouble Shooting Manual.
NO - Rectify.
YES - Continue.
9. Is temperature sender and gauge giving accurate readings?
NO - Sustitute parts and compare readings.
YES - Continue.
10. Carry out cylinder pressure test to determine if pressure is leaking into cooling system causing over pressurising and loss of coolant.
If problem is not diagnosed, check the coolant system for engine oil contamination and engine lubrication system for coolant contamination.
If only the coolant system is contaminated suspect a cylinder head gasket.
If both systems are contaminated, suspect the radiator.
If only the lubrication system is contaminated with coolant, suspect leakage past cylinder liner seals or cylinder head gasket.
It looks like a tight fit to work on those AC fans. A knuckle buster of a job. The manual suggests you remove the radiator to perform test and fan replacement. There are two multiplugs, one for each fan. Perhaps you could reach up (?) and probe each to determine if voltage is present under high heat conditions.
Otherwise, you'd have to drain the coolant, remove the rad, condensor, remove the 8 bolts holding the fan assemblies and then remove the fans for testing. Testing could be as simple as applying 12volts to see if fan motor works. I've not done this on my Disco but that's what I did with my Buick.
More on cooling fans:
Condenser cooling fans
The condenser cooling fans operate automatically whenever the air conditioning system is switched on.
Fan timer unit
The thermostatically controlled timer will continue to operate the cooling fans after the air conditioning or ignition is switched off. When the system temperature is excessive, the fans will operate for 10 minutes to reduce condenser and underbonnet temperature.
