Our VQ40 has 2 radiator looking caps.
The one on the radiator is just a cap with a rubber seal.
The overflow has the internal spring/relief valve.
I've never seen that before. I didnt think the overflow would be part of the pressurised system.
Are my caps on correctly?
I put the chrome NISMO caps on both places and I overheated. Strangely when I first did it I didn't have a problem. Several months later I removed them and right after I replaced them I had the overheating problem.