Unless the O rings have gone bad, in which case leaving them open can cause a vacuum leak. BTW: Those screws are designed to break. They're known as "shear head" screws. Volvo claimed that failure to break them off violated US law -- see the scan in the Files section (screws.jpg): http://autos.groups.yahoo.com/group/dmcnews/files/Other%20PRV%20Literature/ Of course Volvo later advised owners to drill out the sheared off screws and replace them with regular non-shear heads.... Bill Robertson #5939 >--- In dmcnews@xxxxxxxxxxxxxxx, "David Teitelbaum" <jtrealty@...> wrote: > > If you just close the one with the slot in it that is all you need to > do. It controls the other 2 "balance" screws so they can stay open, it > doesn't matter. Just don't tighten them done too much. You can damage > the seat and break the screw. To address comments privately to the moderating team, please address: moderators@xxxxxxxxxxx For more info on the list, tech articles, cars for sale see www.dmcnews.com To search the archives or view files, log in at http://groups.yahoo.com/group/dmcnews Yahoo! Groups Links <*> To visit your group on the web, go to: http://groups.yahoo.com/group/dmcnews/ <*> Your email settings: Individual Email | Traditional <*> To change settings online go to: http://groups.yahoo.com/group/dmcnews/join (Yahoo! ID required) <*> To change settings via email: mailto:dmcnews-digest@xxxxxxxxxxxxxxx mailto:dmcnews-fullfeatured@xxxxxxxxxxxxxxx <*> To unsubscribe from this group, send an email to: dmcnews-unsubscribe@xxxxxxxxxxxxxxx <*> Your use of Yahoo! Groups is subject to: http://docs.yahoo.com/info/terms/