There are two expansion tanks oth with pressure just like other cars. My understanding is the thermostat is in reality an electrically controlled valve(s).
I was told that the rad supplier insisted mmc only accept as a warranty item their same design that failed before. By 2023 the supplier agreed to a new stronger rad design.
I think many new cars now have an ECU controlled coolant thermostat. As I understand it's a familiar wax stat with a tiny heating element in the wax capsule triggered by the ECU to pre-empt coolant warming. I guess this has the advantage of providing a failsafe back to old style thermo mechanical operation to still control coolant temp.
Richard
2018 Roadster 3.7 1966 Land Rover S2a 88 2024 Royal Enfield Guerrilla 450 1945 Guzzi Airone
