Coolant Still overflowing

[Steve Tinker]

Definitely sounds like an air pocket - try lifting the D ring on the expansion valve & leave open for 2-3 days (several heat cycles) and see if the coolant drops even further. Top up as required....

[redeye280z]

Wouldn't leaving the valve open invite air into the system? Shouldn't the valve release any pressure after it reaches a certain amount in the system?

[redeye280z]

I left the valve open for a couple of days and I am still having overflow problems. I can hear hissing coming from the relief valve even after I changed the o rings. I am at a loss. The cap is new the tank and valve are also new.