Positive its on tight enough, I will see what happens if i change the cap over to the other one, the seal may be useless?
I'm sure its something to do with the thermostat switch or something, it gets up to half way on the in car temp guage, its never got that hot before without the fan coming on,
Surely if the switch is faulty then the fan wouldn't be told when to come on, which would explain the problems.
I'll have a play about this afternoon, as I've now printed off the pages from said manual
Thanks for all your help. I can't spoon feed myself Haha