add some color dye (water color ) in radiator when you change the radiator cap,
if the problem persist after changing the radiator cap,
remove the radiator and check in high intensity (lux / lumens) light for any micro leakage, the water color will be peeping from puncture causing pressure leak. Replace radiator core
@def3nder yes it seems head gaskit is intact and issue is in radiator or the cap
@babarhyd @SER_GTR