getting hot

hi before i start . yes!!!! i have trawled through loads of previous post,s regarding over heating ,the story ... whilst out yesturday in my rangey i gave it a boot full coming down the a414 3to4miles , and noticed the temp going up and up , it got to the large white line just before the red , i eased off put the heater on flat out but only cold air came out for a while , IT DID NOT BOIL OVER got it homeand ran through a few things , the top hose woz pressurised , ,, checked it this morning and its fine no fluid loss ,, i did take the top hose off a few weeks ago to drain some water for coolant , ,,
ive got a couple of Q,S. the bleed pipe that goes from the rad to filler tank , how easy should it be to blow through , and wot way would you bleed a coolant system on a 4.0ltr p38 does not have lpg .... and wot temp do they run at ,, thanks gents chewy

fingers crossed i think ive found the problem ... the bleed pipe where it goes into the tank blocked near enough solid with bits of instant gasket ill take it for spank later .. and let you know

seems ok would not have thought to look there if i had,nt searched previous threads