My point is that a workshop manual [preferably in Portugese] will cut short so very many of the problems that you are having yet nowhere in this thread do I see anything that suggests that anybody is using one.

You are clearly able to read English much better than I can read any other language [which makes you smarter than me] so even an English language manual would be better than nothing. The popular Australian 'Gregories' manuals are very good & are writen for the home mechanic with lots od useful pictures & they are not expensive on eBay.

Anybody who wants to look after his Datsun at home should ensure that they have a workshop manual as one of their first purchases once they buy the car.

If you can get a suitable manual locally then I strongly recomend it, if not, then search the world. The 120Y/B210 was quite a popular car & a suitable manual should not be hard to find, but will save you many hours of frustration & many [insert unit of currency here]