Been meaning to reply to this, obviously I misunderstood what you had meant. But, yes, I did replace that cap with a good and “expensive” cap. Thanks!I can’t tell from the photo, but if the radiator has a clamped rubber cap under the expansion tank hose (under the radiator cap), ditch it and look for a silicone cap replacement rated for higher temperatures. An alternative is a piece of heater hose with a bolt and clamp stuck in the end.
The ones that they provide with aftermarket radiators tend to crack after a few months.