[C320-list] Deck filler O-rings

[Dennis Cookson]

Thanks for the fast response, John!  3/32” it is.

Also a good idea re the green filler cap (JohnM), though I can’t see it anywhere here in the UK.

Dennis Cookson
#577

> On 2 Sep 2020, at 13:17, John Stetson <jbstetson721 at gmail.com> wrote:
> 
> 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
>>> 
>>