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?
The cap on the radiator is mainly there for filling the cooling system. Some full size trucks don't have the radiator cap on the radiators. They only have the pressure cap on top of the recovery tank.