[C320-list] Deck filler O-rings

[John Stetson]

Dennis C - I tried the 1/8" rings on the water and diesel and found them to
be too thick.  It caused the cap to sit proud of the ring.


John Stetson
#578


On Wed, Sep 2, 2020 at 7:17 AM John Morrison <sail-ability at sympatico.ca>
wrote:

> Another option is to buy the green Perko diesel filler cap. I did that
> last year as an additional precaution against putting water into the diesel
> tank. What a lousy design to put those identical caps next to one another,
> even a different key to get them off would have been better! The Perko
> comes with it’s own O ring.
> It wouldn’t matter if the O rings on the caps broke, they could still be
> used for sizing.
> JohnM
> 1999#574
>
> Sent from my iPhone
>
> > On Sep 2, 2020, at 5:54 AM, Dennis Cookson <dennis at cooksons.net> wrote:
> >
> > Thanks to both Johns for the replies. I think these rings would break
> if I removed them, they look very old and rather fragile!  But I found this
> useful list of O-ring standard sizes used in the US, as defined by
> Aerospace Standard AS568B:
> >
> > https://www.sealanddesign.com/page/o-ring-size-as568b <
> https://www.sealanddesign.com/page/o-ring-size-as568b>
> >
> > If we can assume that Perko used a US standard size O-ring on these deck
> fillers, at the risk of answering my own question the most likely suspect
> seems to be AS568B -222, which has a nominal ID of 1.5” and cross section
> of 1/8”.   The actual ID is 1.484” and actual cross section is 3.53mm.
> >
> > The other possibility is AS568B -128, which has the same ID but a
> nominal cross section of 3/32”, and an actual cross section of 2.62mm.
> However this appears to be a bit thinner than my existing rings, especially
> given it would be thinner still when stretched.
> >
> > John S - do you think that the 1/8” cross section would be too large for
> the diesel/water filler caps?
> >
> > Dennis Cookson
> > #577
> >
> >
> >
> >> On 1 Sep 2020, at 12:29, John Stetson <jbstetson721 at gmail.com> wrote:
> >>
> >> I just replaced ours.  After a little trial and error, the correct sizes
> >> are:
> >>
> >>  - Water and Diesel - 1-1/2" by 3/32"
> >>  - Waste - 1-3/4" by 1/8"
> >>
> >> West Marine did not have the right sizes, but the local hardware store
> did.
> >>
> >>
> >> John Stetson
> >> Hull #578
> >>
> >>
> >>> On Tue, Sep 1, 2020 at 5:16 AM Dennis Cookson <dennis at cooksons.net>
> wrote:
> >>>
> >>> I need to replace the o-rings in all my deck filler caps, and I can see
> >>> that many owners have done this, but I can’t see any info on the
> size/spec
> >>> of the replacement ring.  Does anyone know the exact spec, especially
> for
> >>> the ring fitted to the diesel filler cap on a 1999 vintage 320?   I
> >>> measured the outer diameter of the filler cap threads at about 41.3mm
> >>> (1.625”) so presumably the o-ring inner diameter needs to be a little
> >>> smaller for a snug fit, perhaps 1.6” or even 1.5”?  The cross section
> >>> diameter appears to be 1/8”.
> >>>
> >>> Are the diesel and water filler caps sizes identical?
> >>>
> >>> Dennis Cookson
> >>> #577
> >
>