Really not sure

Popped over to GSF in Farnham and picked up a new fan thermotime switch and blank:-

Cleaned up the plug having pulled the old terminal out:-

All fitted and another start up done today.
Ran the car for half an hour and no noticeable drop in the level in the reservoir. To be honest I expected some, as you would expect some air in the system somewhere to bleed out but..........no it didn't drop, noticeably

Everything seems to work as advertised. The fans didn't come on straight away, the radiator was cold to start with. Thermostat opened, radiator got hot, temperature gauge reached normal and then fans cut in. Everything worked and no noticeable loss of 'coolant', water in this case.
However........every now then the engine burbles, for want of a better word. Its like a minor misfire and pretty much unnoticeable if you're not listening for it. Every time it does it there is a puff off white 'steam' from the exhaust........I think that a small amount of coolant is being drawn into a cylinder on the induction stroke. This was not noticeable until it reached full temperature/pressure. I'm maybe looking for a problem that isn't there, I don't know, your thoughts would be appreciated.
If my prognosis is right then if I run the car tomorrow with the cap off the reservoir then it shouldn't happen?

Also, if my prognosis proves to be correct then I think this is a very small leak............what are the opinions on my being able to cure, if only temporarily, the problem with a product such as radweld........I'm certain there is a better and more expensive product that would be suited to the purpose

That, I would be happy to try if it saved me taking the head off................I really would value the forums experience and opinions here as personally I'm not a great believer in these 'chemical' fixes
