OK, I did some thinking today and I've decided that I might replace my radiator cap. Maybe it isn't the cap, but if so, it would be a cheap fix. Plus, that wouldn't necessarily show up on a pressure test right? Don't they take the cap off for that test?
Anyway, I decided to order the part, so I did some searching.
AC Delco's site lists "ACDelco Part # RC98" as the radiator cap. Guess what? It looks different than my cap! (There is a picture)
Well, I do a serach on a different site:
https://www.rockauto.com/catalog/raframecatalog.php
Has a photo of the cap and lists it as:
ACDELCO Part # RC98
(replaces RC100 #22671020)
What gives? It appears that GM has replaced the radiator cap for 2006 and 2007 Solstices with a different part. It has slightly different markings and a different part number.
Is it possible they've redesigned the cap?