Hi again. Well things are not looking great. I have had so many opinions etc that I am going to ask the real experts in here!
The disco continues to overheat. My mechanic has replaced the thermostat and that has made no difference. Here is what happens...
I drive along steadily for 15-25 minutes, blower in cab is nice and hot as it should be.
The blower goes cold (lukewarm) for around 5 minutes (temp needle still sat on middle where it should be)
Blower then blows very hot, and power drops, temp needle climbs fairly quickly towards the red when I stop.
I then take the expansion tank cap off, under pressure loads of rusty water gushes out, i then pour in around 4-5 litres of fresh cold water.
I then get the same again, 20 mins or so of driving before repeating this procedure.
My mechanic took the car home one night. He said the water system lost around 2-3 pints in 20 miles. He also said "the water system is being pressurised" which he says is a feature of gasket or head problems. I am not 100% convinced of this yet, but that's what he said, and it suggested to him that its a cracked head or head gasket gone. He spoke to a local expert on landies (someone who deals with all disco servicing and problems for a large car sales place). His questions were "has he changed the coolant bottle cap" (yes i have, with a new one). Then he asked the age, mechanic told him 2000, to which he replied "hmm, i have seen a lot of cracked heads on those models, up til around 2003". So various people seem to think this is a head problem, but I am still not convinced. I am open to the possibility of course, but I am still of the opinion it's a circulation problem. I have NO smoke at all, certainly no blue/white stuff. I have NO sign of water in the oil on dipstick, or creaminess anywhere.
Yesterday the car broke down four times in the above pattern. I filmed what happened when I took the cap off, see video :
After the gushing of hot water stopped, i noticed quite a few particles of rust, so took a photo:
My feeling is the next step is to flush the rad and change the water pump. If the car hasn't had coolant used regularly it could have seized the impeller/motor, which could have rusted up. There is clearly plenty of rust in the system.
Does anyone else have any thoughts on the best steps to take, if not the ones I am thinking of?
Thanks very much