Hi again, don't know why the first address I gave you for the download didn't work, I tested it on my Windows 8 laptop and it downloaded fine.
Still, you got it now.
Secondly, are you aware that 3.9 V8s suffer from problems with the cylinder liners?
anyway, before you get into that have a look at this lot, borrowed from another good LR forum.
It refers to Range Rovers, but that makes no difference.
What are the most common causes of engine overheating?
THERMOSTAT STUCK SHUT
The thermostat, which is usually located in a housing where the upper radiator hose connects to the engine, controls the operating temperature of the engine. It does this by blocking the flow of coolant from the engine to the radiator until the engine reaches a certain temperature (usually 190 to 195 degrees F.). When this temperature is reached, the thermostat opens and allows coolant to circulate from the engine to the radiator.
If the thermostat fails to open, which can happen due to mechanical failure or if a steam pocket forms under the thermostat due to incomplete filling of the cooling system or coolant loss, no coolant will circulate between the engine and radiator, and the engine will quickly overheat.
You can check for this condition by carefully touching the upper radiator hose when the engine is first started and is warming up. If the upper radiator hose does not become hot to the touch within several minutes after starting the engine, it means the thermostat is probably defective and needs to be replaced.
CAUTION: The replacement thermostat should always have the same temperature rating as the original. Do not substitute a colder or hotter thermostat on any vehicle that has computerised engine controls as engine operating temperature affects the operation of the fuel, ignition and emissions control systems.
DEFECTIVE FAN CLUTCH
On rear wheel drive vehicles with belt-driven cooling fan, a "fan clutch" is often used to improve fuel economy. The clutch is a viscous-coupling filled with silicone oil. The clutch allows the fan to slip at high speed, which reduces the parasitic horsepower drag on the engine. If the clutch slips too much, however, the fan may not turn fast enough to keep the engine cool.
The silicone fluid inside the clutch breaks down over time and can leak out due to wear, too. If you see oily streaks radiating outward on the clutch (and/or the fan can be spun by hand with little or no resistance when the engine is off), it means the clutch is bad and needs to be replaced. Any play or wobble in the fan due to wear in the clutch also signals the need for a new clutch.
INOPERATIVE FAN MOTOR
On most front-wheel drive cars, the fan that cools the radiator is driven by an electric motor. A temperature switch or coolant sensor on the engine cycles the fan on and off as additional cooling is needed. If the temperature switch or coolant sensor (or the relay that routes power to the fan motor is bad), the fan won't come on when it is needed and the engine will overheat. Likewise, if the fan motor itself is bad, the fan won't work.
The system needs to be diagnosed to determine where the problem is so the correct component can be replaced.
EXTERNAL COOLANT LEAKS
Leaks in radiator or heater hoses, the water pump, radiator, heater core or engine freeze plugs can allow coolant to escape. No engine can tolerate the loss of coolant for very long, so it usually overheats as soon as a leak develops.
A visual inspection of the cooling system and engine will usually reveal where the coolant is going.
Leaks in hoses can only be fixed by replacing the hose. Leaks in the water pump also require replacing the pump. But leaks in a radiator, heater hose or freeze plug may sometimes respond to a sealer added to the cooling system.
WEAK OR LEAKY RADIATOR CAP
If no leaks are apparent, the radiator cap should be pressure tested to make sure it is holding the specified pressure. If the spring inside the cap is weak (or the cap is the wrong one for the application), the engine will lose coolant out the overflow tube every time it gets hot.
INTERNAL COOLANT LEAK
If there are no visible coolant leaks, but the engine is using coolant, there may be a crack in the cylinder head or block, or a leaky head gasket that is allowing coolant to escape into the combustion chamber or crankcase.
EXHAUST RESTRICTION
In some instances a severe exhaust restriction can produce enough back pressure to cause an engine to overheat. The most likely cause of the blockage would be a plugged catalytic converter or a crushed or damaged pipe. Checking intake vacuum and/or exhaust back pressure can diagnose this kind of problem.
BAD WATER PUMP
In a high mileage engine, the impeller that pumps the coolant through the engine inside the water pump may be so badly corroded that the blades are loose or eaten away. If such is the case, the pump must be replaced.
Most pump failures, however, occur at the pump shaft bearing and seal. After tens of thousands of miles of operation, the bearing and seal wear out. Coolant starts to leak out past the shaft seal, which may cause the engine to overheat due to the loss of coolant. A sealer additive will not stop this kind of leak. Replacing the water pump is the only cure.
CAUTION: A leaky water pump should be replaced without delay
CHECK CIRCULATION
Another frequent contributor to overheating. If the thermostat doesn't stop things up, your water pump might. Check out your circulation by removing the Radiator Cap, rev to 2000 rpm and when the Coolant starts to warm a flow should be able to be seen.
GIVE 50%
Incorrect water to antifreeze mixtures can cause your auto to overheat. A mixture that is lean on anti-freeze is often the culprit when the overheating is consistent.
CHECK HOSES
Older hoses sometimes collapse from suction and can inhibit flow at higher speeds.
FUEL ISSUES
If a motor is leaning out it will run much hotter.
Retarded or over advanced ignition timing (may also contribute to detonation and preignition).
RADIATOR
The most common problems radiators fall prey to are clogging (both internal and external) and leaks. Dirt, bugs and debris can block airflow through the core and reduce the radiator’s ability to dissipate heat. Internal corrosion and an accumulation of deposits can likewise inhibit coolant circulation and reduce cooling. A good way to find clogs is to use an inferred thermometer to "scan" the surface of the radiator for cold spots. If clogged, the radiator should be removed for cleaning or be replaced.
Back flushing the cooling system and/or using chemical cleaners can remove rust and hard water scale, but may do little to open up a clogged radiator.
REFILLING
When refilling the cooling system, be sure you get it completely full. Air pockets in the head(s), heater core and below the thermostat can interfere with proper coolant circulation and cooling. If the cooling system has no bleeder valves to vent air, you may have to temporarily loosen a heater hose to get all the air out of the system.
OVERHEATED INCOMMING AIR
On older vehicles with a carburettor or throttle body injection, check the operation of the heated air intake system on the air cleaner. If the temperature control valve is stuck so only heated air from around the exhaust manifold is drawn into the air cleaner; it may contribute to detonation and/or overheating. Also check the heat riser valve for manifold heat on older V6 and V8 engines. If stuck shut, it may be overheating the intake manifold.
DRAGGING BRAKES
A calliper that’s sticking or park brakes that isn’t releasing may be making the engine work too hard.
OVERWORKED ENGINE
The cooling systems in many passenger cars today are marginal and have little excess capacity to handle extra heat generated by towing or high speed mountain driving in hot weather.
As for the cleaning of the radiator it needs to be done professionally it will cost you about $100 if you take the radiator out yourself. They totally dismantle the radiator clean and rod it put it back together repaint it and pressure test it. Flushing and reverse flushing will not help if there is a blockage in the radiator. Go to supercheap and buy one those mechanical temp gauges so you can actually see what the temperature is reading.
. First, check to see that the gauge is working. Range Rover sending units have a horrible tendency of going bad and spiking, causing the operator to think the temp is too high. They are cheap and easy to replace, and one of the first things to do when diagnosing a cooling system.
If you have access to a laser thermometer, you can check the temperature to see how it’s actually running, by pointing the laser at the water neck where the upper rad hose meets the water pump. This number should be anywhere from 190-210* F when in normal operating range.
In short, don't go replacing radiators and water pumps before you verify that you're actually overheating!
Best of luck
