wot engine is it eg engine code hopefully i can advise on your next step
replaced radiator
replaced thermostat
replaced expansion cap
done leak test, no liquid colour change
no visible leaks anywhere, both myself and garage can not see any
but system still pressurising after every trip
going through water like billy-o and steaming like a chinese laundery, heater is fine, car hasnt overheated, runs rough though even though ive changed both crankshaft and camshaft senders,...
it can only be the head yes?