francophile1947 wrote:The reason the header tank is cold is an airlock stopping the water circulating - you really mustn't drive it until the system has been bled.
The header tank is bubbling hot when it overheats...however,
I've just brought it back from where I left it, 1/2 a mile away. Put about a litre of water in the in the header tank, started fine. Wifey follows me back under scrict instructions to watch the exhaust for steam or white smoke.
Got back ok, NO smoke or steam from the rear, didn't really overheat, didn't really move from the 11 o'clock position so I thought I'd leave it idling on the drive while watching it like a hawk. 10 mins later...nothing. Gauge still at 11 and no sign of moving, header tank and radiator top hose are warmish but not hot. Hoses underneath the seats are pretty hot but not unusually so I think. The cooling fans were going but not the scavenger. I turned it all off after 15 mins as I think it would've stayed like that all day.
Why would it overheat going along but not idling when there is no air rushing through the radiator?
So, any further thoughts anyone? ( trying to give as much info as possible)....
Thanks everyone for your input so far...much appreciated....
...and to the Eat Aunt..STFU says your marmalade is in your cupboard!!.....