Silly question here, but...Where is the radiator cap on a Vanagon? I want to perform a pre-purchase cooling system pressure check as described by Boston Bob on a Vanagon that isn't sitting in my driveway at the moment. I visualized myself replacing the radiator cap with the tester, then realized I have no idea where the radiator cap is on these things. Front? Back? Is it on the coolant overflow tank? Any special adaptors needed? See I'm thinking about my Honda, and I know where that cap is...

Bonus question: What kind of readings should I expect on a compression check of a 2.1 with 155k miles on it?