D.E Posted June 2, 2015 Share Posted June 2, 2015 Went for a ride to recharge A/C and had to get gas and had lot of pressure when removed gas cap and tank made a bong.It is org cap suppose to be vented I guess.But it is a new tank.Never had this since I had this car since new.Thanks for help Link to comment Share on other sites More sharing options...
iceman Posted June 2, 2015 Share Posted June 2, 2015 D.E ... search in this forum for gas tank pressure. There was a thread about this and some issues with new tanks. Link to comment Share on other sites More sharing options...
iceman Posted June 2, 2015 Share Posted June 2, 2015 Wait ... found it for you. http://www.firstgenmc.com/forums/index.php?/topic/13621-gas-cap/ Link to comment Share on other sites More sharing options...
D.E Posted June 3, 2015 Author Share Posted June 3, 2015 It is a repop tank.will look into it don't like it to build up pressure.As with most repop stuff JUNK now days Link to comment Share on other sites More sharing options...
MCfan Posted June 3, 2015 Share Posted June 3, 2015 I've owned three '70s (including one new from the dealer in 1970) and they all build pressure in the gas tank with the stock vented cap. I have replaced one leaking factory tank with a repop and it behaves exactly the same. I have examined the gas caps and they are definitely vented, however, I am convinced that it takes a certain threshhold pressure before they activate. That threshhold pressure will be present when you stop to fill up your tank, although it will bleed off slowly if your Monte is parked for awhile. I believe this was done on purpose because the filler neck is very low and straight out the back of the tank. When I go through the first three gears on my four speed, I have often been told (by a well-meaning guy at the next stop light) that my tank is leaking. Every time I have checked, the cap is on tightly. Any hole you drill in the cap will leak gas under acceleration - how much do you want to leak? Link to comment Share on other sites More sharing options...
Monteman1971 Posted June 3, 2015 Share Posted June 3, 2015 I'd swap the gas cap. Sounds like your getting way too much pressure. I hear the locking gas caps vent better. Link to comment Share on other sites More sharing options...
D.E Posted June 4, 2015 Author Share Posted June 4, 2015 Thanks I don't remember it ever doing that since it was new in 71.But will just live with it Link to comment Share on other sites More sharing options...
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