Hello Dave,
thanks for your fast reply :)
I will definitely do your checks. But please wait a bit. I am pretty busy every day so it will take time.
The car has always been in perfect condition. No previous issues were known before doing that big maintenance on the car.
I don't know if the head was checked before the new gasket was fitted (I think yes, see below)
In the meantime I would have a clarification.
What do you mean with "the airlock"? Do you mean a bubble inside the coolant circuit?
I unscrewed a bit the radiator cap with the engine on normal working temperature and some coolant has gone out. I think there is no bubble inside. Anyway I can redo the same test if you think it needs to be done again.
Tomorrow I'm going to check if the the heater gives a good heat inside the c**kpit and if I have enough time I will try to check if the radiator fan kicks in by put on ground the wire; that's because now is really cold and is hard to makes the engine reach a temperature beyond the 100C
Last but not least I have retrieved the invoice which list what components have been changed (note: I have used an online translator); the components that have been changed are:
item codes and description from google (not sure if I can post links. Feel free to delete them)
5232xs - TIMING BELT - https://www.fabioizzoautoricambi.it/cinghia-distribuzione/1518-94158-5232xs-cinghia-distribuzione-honda-civic-cassa-77a-disponibile-gates-3-pz-5412571007237.html
03130 - (not sure in English -> tensioner bearing distribution
https://www.ebay.it/itm/TENDICINGHIA-DISTRIBUZIONE-MTD155HQ-1987949307-0068401-ATB2084-14510PM700-03130-/174169391975
4pk795 belt - not further description
https://www.pezzidiricambio24.it/779321-gates
4pk812 belt - not further description
https://www.auto-doc.it/dayco/221532
4pk788 belt - not further description
https://www.auto-doc.it/dayco/221528
428pa - water pump
and coolant liquid
About engine head/head gaskets.. it has not been replaced (the invoice does not have anything related to). Anyway I remember that the mechanic said something about the head. Maybe they have dismounted it to perform other jobs like changing the belts?
Thanks again David,
have a good day