I'm leaning towards head gasket!

my mate has the same prob with hi el xr6 he found that the thermostat wasnt working properly, gave it a tap with a hammer and it realeasied and the pressure dropped instanly, same prob u r having, after he turnerd it off he lost water over the over flow tank and the hoses was like rock hard hope this helps cheers

i love the way everyone thinks when an e series has a heating problem it's instantly a headgasket.
if it's pressurising after shutdown how do you get combustion pressure bleed off when the engine isn't combusting!? it's thermal runaway, everycar suffers to some degree from it, some worse then others and it's condition dependant. i can't say exactly what it is, but i'd start replacing everything starting with cap, thermostat, hoses & pipes. & can also do a radiator flush but i don't think this is your problem.
also are you running a glycol mixture ? i ran glycol in mine coz i thought i would benifit from the anti boil properties, in time i figured out this was only a bandaid solution and not a good one, you culd actually hear my coolant boiling inside the block a little after shutdown, this is because glycol reduces waters ability to tranfser heat. meaning all the heat stays in the block, so does the coolant, then it boils, creates pressure and spits it out the overflow (read: cap functioning properly) if it wasn't for that cap it would split a hose and spray boiling coolant everywhere at high pressure.

the return pipe in mine from the pump to the thermostat housing causes hot running on first thermostat cycle because the water pump isn't pushing the water anywhere, and mine also pushes oodles of water out on shutdown to, i accredit this to the same problem and the water has nowhere else to, making the thermal runaway worse.
i really feel that mild steel, (already at a disadvantage) paper thin bypass tube is absolutely piss poor engineering on fords part, and after 20 years they still have them ! frigin riduclous. why couldn't they just accept the 20% increase in cost and use stainless and have it last forever ? oh thats right because then we wouldn't have to overhaul our cooling systems as much and they would be morereliable and then ford service would be loosing money.

Has anyone tried hooking up a electric water pump and tried to run a system where the thermo's and water pump stay running after engine shut of for a certain time?

Well since it's a pressurisation issue, the headgasket sealing can still be suspect, and it needs to be ruled out.
Exactly as I've described earlier - the combustion gases venture into the cooling system under a headgasket firing ring - when cold the cylinder compression holds pressure in the cooling system.
Here's more good news - if your hoses, cap, etc are in good order, a compression test will come up good on the leaking cylinder, as will a pressure test on the cooling system.
Best way to know is as a number of us have said, is get the coolant tested for combustion gasses.

Funnily enough, some of us do base our info on real life situations.

thats good snap, i'm not out to prove people wrong, specially when i only base my knowledge on what i have 'actually' experienced. how many people do that kind of testing round here though ?

Start the car cold with the radiator cap removed. If you see bubbles of air coming from the radiator filler tube at the bottom of the reservoir tank then you have either got a stuffed head gasket or cracked head. You should have already checked this by now, was mentioned in a previous post..........................................

And no one has said you were - but in these situations, the HG is maybe still a factor, but a very easy gas test is a quick, non expensive way to determine it.
He can then move onto the rad cap, thermostat, etc.

Those that want to solve their problem. A comp test was mentioned in this thread - thing is though, it's results may be inconclusive, as maybe a cooling system pressure test.

As I previously mentioned I had the exact same issue - now have changed head gasket and no issue............

My Problem Conclusively SOLVED

Heater Pipes, Heat Core, Radiator, Radiator Hoses, Radiator Cap, Thermostat ALL had been changed prior to changing the head gasket and I still had the same issue of too much pressure.

Yes it may be a sticky thermostat or soemthing else but in my case it was the Head Gasket

Thanks alot for all the info guys, ive flushed the cooling system the other day, made it better, but now the hose from the thermostat to the radiator needs replacing as its leaking, apart from that there is no pressure, but that would be as a direct result of the leak, lol.

Does the Teekay test a pretty simple test, i imagine its as simple as hooking up a multimeter to a battery

Im pulling out the thermostat tonight, test it in a boililing pot of water, if it works ill drill a few medium sized holes in it and see how we go

f**k cars Atleast i've got a few weeks to fix it

mine was doing the exact same thing but i could smell like exhaust gasses in the water bottle ,mine was the head gasket .water got dirty really quick as well .

with the cooling system flushed its back to normal pressure

still takes two turns of the key to start it but hey, im not spending $1k to stop that, plus i like having an excuse to open the bonnet and pour water into it lmao

with the cooling system flushed its back to normal pressure

still takes two turns of the key to start it but hey, im not spending $1k to stop that, plus i like having an excuse to open the bonnet and pour water into it lmao