I've already seen the bulletin regarding the sill drainage, that's on the 'back burner' at the minute!
Today, with fresh enthusiasm, I went out to tackle the cooling system again. I started with the thermostat housing a discovered I'd made the schoolboy error of not fitting in the recess in the block properly. I thought I had, but I'd clearly clamped it in it's housing's mating faces. I put all this right and made myself a new gasket and refitted, NOW; Ive fitted the thermostat with the dome towards the radiator hose as per the picture here:
http://www.lotuselancentral.com/repair/thermostat.htmbut when I removed the old one yesterday, it was the other way around and I assumed fitted incorrectly (the dome was in the block with the brass waxstat and spring towards the top rad hose).
Anyway, all leaks here are gone. Refilled with coolant and started the car. Bleed the air out of the top of the radiation (under the headlamp pod). With the engine cold and the thermostat shut, when you rev the engine the coolant level in the tank goes from the cold level and rises dramatically. I didn't want to rev it too much because that's why I think the cap went yesterday. You only have to hold moderate revs to fill the expansion tank. This changes when the thermostat opens, the level returns to something more normal and the coolant enters the tank through the top hose when you rev it and the level is pretty stable.
I left it sat on the drive ticking over till the radiator fans come in and it's fine. When you stop the engine and let it cool, the same process happens again until the thermostat opens.
I've tried an old filler cap (black) from the spares I got with the car and the cooling system never pressured (no release of pressure when you remove the cap). I reverted back to the one that was fitted, a yellow Topran part. That does build up pressure, but that's the one that blew off yesterday. I don't like Topran either, they're rubbish aftermarket tat. Either cap though, the symptoms are the same until the thermostat opens.
Have I fitted the thermostat wrong? Should there be a bypass to prevent system over pressurisation when the thermostat is shut?I was starting to think my head gasket is on the way out again but I removed the plugs and done a warm compression test. All cylinders are 12Bar (170psi). They're all bang on the same.
The plugs look like this:


No more leaking fuel though!!!
I'm realise a new set of plugs wont hurt either. I'll service the car when I'm a bit happier with it.
I've taken a video of the coolant tank that I'll try posting later in the week.