Those idle tests I was doing were after I had taken it for its first test drive during the test drive, the thermostat opened and filled the radiator, thus taking a lot of water away from the engine, creating an airlock which gave me overheating and extreme pressure. :doh:
Anyway, then I did the idle tests, adding more hot water as necessary, and as You say, Jug, they seemed to go ok.
So I drained (and flushed) the engine because it was just 100% water, and the water was rusty, I also removed and flushed the rad again with clean water.
This time I refilled it with 3 litres of antifreeze. and a couple litres of water. But I realised what the problem was. The bottom hose from the rad goes to the thermostat, which is closed when cold, so the rad was not filling with water, the air had nowhere to go.
So this time when I refilled it from scratch I loosened the rad bottom hose at the thermostat end until the coolant came out of the rad pipe, re-clipped the rad pipe and bled the air out.
Took it for a short run re-bleed the screws. Took it for another run and it was perfect. Came home another short bleed, left it to idle for the fan to come on - ok.
It's fixed :woot: ...... for now :chin:
Costs for head gasket change:
Head Gasket - £32 (MLS - Multi Layered Steel) not original
Exhaust gasket £12 - original Fiat
Waterpipe to cylinder head gasket £2.50 Original - Removed in error.
5 litres antifreeze £9.50 (used 3)
New tailor made stainless steel studs £2
Recycled copper-plated exhaust-stud nuts from an old car (free)
Re-used old head bolts (free) not recommended! & torqued to 65Nm + 90° +90° (old bolts not torqued as much as new bolts - new bolts would require another 90°)
Re-used Cam cover rubber gasket - cleaned & set with new silicone.
Sub Total £59
Draper Ribe bit set £22 (ebay)
12 & 13mm deep sockets £4.50
Draper torque wrench angle gauge £4
Sub Total £30
Future forseeable costs
Air duct pipe between Air Flow Meter and Turbo, has a hole in it, new £25, hope to find one in scrap yard.
Oil & filter