Looks like water seal failure, right? Vid. inside
 

Warm iddle, 82°C, I've not revved the car since start-up, it just warmed-up gently:

http://www.youtube.com/watch?v=Thu7p-UEvVk

Then I revved it (sorry my light died for this take):

http://www.youtube.com/watch?v=OzyK04WHeH0

Funny thing is that I checked my overflow tank right after, level was low. I guess because I ran the car with no cap on the filler neck, there was still coolant in the "funnel" ; but more curious was that the coolant on the stick was COLD! :Wconfused

Coolant has never overflowed in this car. As per my temp. gauge indication (sensor on the upper rad. hose) it has never overheated.

So from this test, is this 100% sure I have water seal failure or can it be somthing external (I thought also of my turbos)?

Thanks for your shares.

Yeah its blown.

Does it smoke white steamy smoke on startup?

Sometimes yes, more often now. But just 10 sec.

Start-up on one rotor or like it was flooded, then cleans-up when applying throttle, backfires like hell and everything goes back to normal. Sometimes a bit of smoke above the turbo area during warm-up, that doesn't stay.

Spark-plugs are clean & dry but white/grey colour.

I was hoping for a flooding issue due to injector leaking + turbo leaking coolant & oil as I always have quite amount of shit on the floor in this area, but looking now at the test...

Kind of hard to tell from the videos. Was the car fully warmed up so that the thermostat was open? Are the light spots/areas around the edge bubbles? The larger reflections appear to be just turbulence. If the light spots are bubbles you probably have a minor coolant seal leak.

Is the white/grey color your mention the color of the center insulator on the spark plugs? If so, and unless they are new, that could be another indication of coolant in the combustion area. Start saving for a rebuild, but if it were me, I would continue to drive the car until a more definitive sign of a coolant seal problem is evident.

The "Champagne test" is far from definitive. (Yes, even in France) Take the car to a trusted shop that has a hydrocarbon sniffer, there called smog test stations here in the U. S. , but I'm sure you have an equivalent in France. Have them test at the filler neck for hydrocarbons while the car is running.


Paul

The 7 is supposed to be at my mazda mechanic next Wednesday, I've scheduled a pressure test and will ask them to perform the sniff test as well.
Here are some more vids, more explicit, with the white smoke at cold start, the smoke in the turbo area, and champagne test at day light.

Cold start (fuel pressure gauge was still showing 2bar pressure after 48h!):
http://www.youtube.com/watch?v=EFu272UEe7I

Smoke turbo area:
http://www.youtube.com/watch?v=KnGmMikRiKc

Champagne test, thermostat just opened:
http://www.youtube.com/watch?v=uJ4Tyrw8Svs
No bubbles, just shaky when the fans turned on

Champagne test when opening throttle:
http://www.youtube.com/watch?v=Rj9-IFyvRlc

Also shaky, I had to hold the funnel to have good readings. Bubbles appear only when I rev it.
Same bubbles appeared after I stope the engine and pressed the upper rad. hose.

The first video definitely looks like a coolant seal failure cold start :(

Yep, and it's not very noticeable but I had to help the second rotor to start, or at least getting to a normal iddle, by revving a little.