Differences between OEM gas cap (with rubber gasket), and aftermarket one w/o gasket? | FerrariChat
Buy

Differences between OEM gas cap (with rubber gasket), and aftermarket one w/o gasket?

Discussion in 'Technical Q&A' started by Mike328, Jul 14, 2005.

This site may earn a commission from merchant affiliate links, including eBay, Amazon, Skimlinks, and others.

  1. Mike328

    Mike328 F1 Rookie

    Oct 19, 2002
    2,655
    Boulder, CO
    Full Name:
    Mike
    #1 Mike328, Jul 14, 2005
    Last edited by a moderator: Sep 7, 2017
    No doubt we've all seen the pretty aluminum gas caps available for our 308s through 355s (testarossas and modials too, I think).

    They are certainly a nice piece (I just bought one from site sponsor Ricambi, http://www.ricambiamerica.com/index.php).

    The stock ones have a rubber gasket of sorts inserted into it, and held in place apparently by the threaded metal inside of the cap. It has a round "ridge" ring present just inside of the threaded cap side.

    This rubber piece is not present on the aftermarket caps. The result is, it "seals" a bit differently when tightening; the stock one I can feel it kind of compress against the rubber.

    Now, it's possible the aftermarket ones seal just fine.

    But my question is, how important is it to seal of the gas tank? When I unscrew it after burning around 15 gallons or so, I can sense a significant "whoosh" (SUCTION, I believe, though am not positive), and this encourages me to open it slowly... like I would a shaken up bottle of coke :). You get the picture. So the seal is doing something.

    Is there room for any concern here if the aftermarket gas cap doesn't seal? Are six or so ranks of threads on the gas cap enough to form a seal, anyway? Is the "whooshing" sound when unscrewing the gas cap normal?


    Thanks,

    --Mike
    Image Unavailable, Please Login
     
  2. Verell

    Verell F1 Veteran
    Consultant Owner

    May 5, 2001
    7,022
    Groton, MA
    Full Name:
    Verell Boaen
    #2 Verell, Jul 15, 2005
    I believe the only purpose in sealing is emissions control by forcing all vapors thru the charcoal canister.

    The system gets pressurized because the fuel is heated by it's constant circulation by the fuel pump! The 'whoosh' is the pressure being released. The pressure is not needed for the CIS injection system to work normally. In near freezing weather, I've noticed that my system doesn't seem to build up any pressure when running.

    You certainly want a minimum amount of sealing so that fuel doesn't leak out during hard right high-speed turns w/full tanks. Probably not an issue except on the track, but better safe...
     
  3. Ricambi America

    Ricambi America F1 World Champ
    Sponsor Owner

    Dec 7, 2003
    16,393
    Winston Salem, NC
    #3 Ricambi America, Jul 15, 2005
    Mike -

    I don't think is the picture of one of my gas caps (unless my monitor is messed up). The caps that I have are more "brushed" in their aluminum appearance, and have a rubber gasket that does sit in the bottom of the cap itself. See the lower picture here: http://ricambiamerica.com/product_info.php?products_id=261141

    The one I sent should have that black gasket in the base. If not, send it back and I'll get you a new one ASAP.


    Best,
    Daniel
     
  4. enjoythemusic

    enjoythemusic F1 World Champ

    Apr 20, 2002
    10,676
    Worldwide
    Full Name:
    Steven
    #4 enjoythemusic, Jul 15, 2005
    Mike, i have one of those caps i bought from Sodacom and it has the soft black plastic insert. Yours seems to be missing it.
     

Share This Page