good idea there....i had the very same problem on my vr6.
i recomend getting a new cap.i believe i payed about $25 for a genuine one for a vr6
Where about's did you get it from?
I've solved my pressure problem for the short term, but pulling the rubber ring out and flipping it over, of course since there's a huge groove cut into the opposite side this won't last forever and a replacement is needed

Also, Radiator was flushed today, nice green coloured coolant now, no more floaties, one less thing to work on.
Next up i'll swap the oil/ oil filter, then the belts need a check up, get her all serviced while I'm ahead

, I beleive a timing belt is out? when I turn the car over there is a ticking coming from the engine, until its been reved/ warmed up... something interesting to look into
http://www.youtube.com/watch?v=X9mYq38dviE quick video of the car all cleaned up, and the damaged drivers seat (out of a jetta) to give you all an idea of what im looking into repairing/ replacing
Edit
for some reason theres no sound... will shoot all future video with the missuses camera
