radiator holding pressure over night

[dodgey68]

I am not sure if this is good or bad, my question is , if the radiator still holds pressure after 24 hours some times  even longer is this normal , is this a god thing as at least the system doesn't  have any leaks  or is the rad cap the wrong one??,, thank you

[John_Kunkel]

Normally the system pressure will drop from its highest value as the coolant cools and contracts but holding some pressure is a good thing. IOW, if the system pressure was 14 psi while running at operating temperature, it might drop to 6-8 psi in 24 hours but thats normal.

[fy469rtse]

Dodgey ,
I had an issue with mine recently , where I would come back days later and was holding pressure,
it started running a little warmer ,
leaks started appearing in the weakest or less tightened hoses
it wasn't pulling or putting excess coolant in recovery bottle,
dodgey radiator cap ,
replaced it , bingo ,
you could confirm with coolant system pressure tester ,
geoff 
oh fellow, aussie member

[redgum78]

Sounds like time for a new rad cap.

[dodgey68]

ok im gunna ask a silly question,,i am going to get a new rad cap, but what psi/ kpa     the one on it is a 13/90,, i found a new one in shed 20/135,,
what is good for these old cars,,

its a new alloy rad, and just a normal standard  440,