speaking of fans, ive got a 92 disco, with aircon, (twin fans).
never had problems with overheating untill 2 weeks ago, towing the caravan down m5, disco decides to start overheating until i had to stop as needle on the gauge went into the red and the red light came on, since stopping about 10 times on the way to weston then back to brum, ive had the thermostat changed and a new viscous fan fitted, ime not loosing any water, around town the disco is fine but put it on a motorway even without towing and ime having to controll the engine temp with the accelerator, go up a hill and it starts to strugle, give it power and the temp goes up rapidly, get to the top and come down other side, ease off the power and temp drops,.
ive been told a possible head gasket,
any ideas anyone ? please
Had the same problem but to a lesser amount, the radiator tubes are probably blocked. I am talking the tubes that carry the water, but also check with a torch and see if you can see light through the fins of the rad.
When driving slowly or with the engine not under load the rad can cope but start to make it work and this is the normal signs of a blocked rad.
Most air con cars are noted for getting dead leaves, bugs, small children ect caught between the two rads. It is easy to undo the engine rad and clean out the crap, do not loosen the air con rad or it will need regassing!
Other than that assuming your fan belt is tight and driving the water pump ok then take the plug out of the top of the rad when COOL and drain off some water so you can see the tubes. If they look even slightly crudy or blocked get the rad rebuilt or a new one.
Another tip is get the engine hot and watch the bottom hose as you rev the engine quickly from idle, sometimes the bottom hose gets soft and starts to collapse on itself restricting flow, this is a common problem out here (on all makes) because of the heat.
To help with the check of the head gasket take of the expansion cap carefully when the engine is warm and the thermostat is open and look for bubbles (read big bubbles) in the water.
You do not state if it is petrol or diesel but if a petrol V8 then the distributor has been known to stick in the retard position causing overheating at high speed and when towing heavy loads.
Binding brakes but again unlikely.
You state that you are not loosing water and to be honest once the head gasket starts blowing into the cooling system which is rated at about 13psi and cylinder pressures in the 250 psi or 400psi + (diesel) it is not long before water starts getting forced out of the cap, so at the moment of writing the head gasket sounds OK but it will not last if you keep running hot.
You can also get a chemical test to detect combustion gases in the coolant.
No doubt somebody will come along with some other ideas so keep checking back.
Hope this helps
regards
Dave
