i have a 1998 p38 4.6 hse that has just spent 4 weeks in a garrage having head gaskets done but it still overheats changed pump thermostate and checked all hoses but when ticking over it sits at bang on half way temp but when you drive it gose about a mile then temp suddenly rises and all water floods out exspansion tank any ideas or is there a plymouth area person knows how to bleed the thing before i go insane

Have you refilled per Rave, blown through hose from top of rad to expansion tank to make sure it's clear, I have emptied and refilled my cooling system umpteen times due to replacing hoses, pump, o rings and never had any issues. I start by clearing said hose, then whilst filling now an then blow into expansion tank to push the coolant round the engine, once a steady stream of cooling flows from bleed nipple on top of rad reconnect hose top up tank to min mark then run engine up to temp with the cap off, whilst engine is running rev a few times and you will see air bubbles going into tank, usually from heater matrix, keep reving until bubbles stop and check both heater hoses are hot, once hot switch off let cool and recheck level.
Hope this helps.
Paul.

The garage is supposed to refill the coolant after a engine head gasket replacement. So you already paid to get the problem fixed. Go back to the garage and do not let them abuse your good nature.

Else, coolant blowing out after driving 1 minute is indicative of a failed water pump or leaky head gasket both of which are new or maybe low coolant level.

I just replaced the water pump (leaky weep hole for several days) on the 2001 4.6 HSE 124Kmiles whose engine temp suddenly rose as a result of low coolant half a gallon (when at first investigating the temp rise).