Today at Atelier Kaz - ex-Honda R&D, F1, Indy/CART engineer

By the way, while investigating the coolant leakage, found out there are lots and lots of air trapped in the heater core.
It is very likely to be from the radiator leakage and this could be the reason for the trace of coolant markings at the overflow tube at the header tank but as a precaution, decided to carry out the eng block test.















The fresh test fluid out of the container.



Cycled through the air inside the header tank for about 1min. Not even a tiny change of colour so that's good.



As a comparison, just one cycle of exhaust gas will add hint of yellow-ish colour, like dark green.



The 2nd 'puff' was enough to make it yellow.
You don't want seeing this on your engine.


















I don't like the way this water valve sits (yellow car).

Should be like this (red car).

Can't see further back so not sure why it's sitting with some angle so will investigate it once the blower fan is removed.

















By the way, the owner told me that all of the coolant hoses were replaced in the past but I don't think so.
The font and the text on this hose are still the original one......