Larry - When a gas cap is vented, it means that there is a small hole in the cap to equalize pressure between the inside of the tank and the outside. It is *critical* that you have a vented cap. Please verify this. If the cap doesn't specifically say Vented on the front, then replace it. Another thing you should check is that the gas tank filler tube has the 'notch' facing toward the top. Ron ----- Original Message ----- From: "Larry Jabin" <larry@xxxxxxxxxx> To: <Chrysler300@xxxxxxxxxxxxxxx> Sent: Sunday, March 04, 2012 11:27 PM Subject: [Chrysler300] 1958 330d gas cap Yesterday after driving my car about 50 miles I removed the gas cap & there was a big swoosh of air going INTO the tank The tank was about ¼ full The cap is vented but I guess the vent must have stuck closed so I tried to clear with air pressure Today I drove the car again it was a great day temp in the low 70s But when I removed the cap after driving it for a while This time another big swoosh of air but coming OUT of the tank So somehow the tank was creating pressure I would drive it 20 miles & check it again , same thing a couple times Has anybody experienced this Also is the vented cap supposed to release pressure both ways in & out? Also where can I purchase a correct cap? Thanks Larry Jabin San Francisco CA 94111 Larry@xxxxxxxxxx<mailto:Larry@xxxxxxxxxx> [Non-text portions of this message have been removed] ------------------------------------ To send a message to this group, send an email to: Chrysler300@xxxxxxxxxxxxxxx To unsubscribe from this group, send an email to bob@xxxxxxxxxxxxx or go to http://autos.groups.yahoo.com/group/Chrysler300/join and select the "Leave Group" button For list server instructions, go to http://www.chrysler300club.com/yahoolist/inst.htm For archives go to http://www.forwardlook.net/300-archive/search.htm#querylangYahoo! Groups Links ------------------------------------ To send a message to this group, send an email to: Chrysler300@xxxxxxxxxxxxxxx To unsubscribe from this group, send an email to bob@xxxxxxxxxxxxx or go to http://autos.groups.yahoo.com/group/Chrysler300/join and select the "Leave Group" button For list server instructions, go to http://www.chrysler300club.com/yahoolist/inst.htm For archives go to http://www.forwardlook.net/300-archive/search.htm#querylangYahoo! Groups Links <*> To visit your group on the web, go to: http://groups.yahoo.com/group/Chrysler300/ <*> Your email settings: Individual Email | Traditional <*> To change settings online go to: http://groups.yahoo.com/group/Chrysler300/join (Yahoo! ID required) <*> To change settings via email: Chrysler300-digest@xxxxxxxxxxxxxxx Chrysler300-fullfeatured@xxxxxxxxxxxxxxx <*> To unsubscribe from this group, send an email to: Chrysler300-unsubscribe@xxxxxxxxxxxxxxx <*> Your use of Yahoo! Groups is subject to: http://docs.yahoo.com/info/terms/