My wife's car started giving off a whif of coolant the other day. I thought I'd start with a new cap since the original one is 6 years old with about 60K miles on it. The cap I purchased does not have a spring on the vent valve. I could swear that vent valve has always been lightly spring loaded. But I went to two other auto parts stores and found caps with no spring on the vent valve. If you hold the cap horizontally, the vent valve dangles. Is that they way it's done these days. I'm not dreaming about the spring am I?

The caps with no spring on the vent are for systems with coolant recovery bottles, it allows the coolant to be pulled back into the radiator more easily. Usually they are marked "coolant recovery".
David

Dave,
You did not mention what type of car, but lately I wont use anything but a factory cap. I have heard many stories of problems with aftermarket ones, especially in import cars.