[C320-list] Deck filler O-rings

[John morrison]

I don’t have a part# to hand. I just bought it from our local chandlery here. It does sit a bit proud of the stainless steel threaded portion but is completely watertight!
JohnM, 1999#574
> On Sep 2, 2020, at 8:36 AM, Dennis Cookson <dennis at cooksons.net> wrote:
> 
> 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
>>>> 
>>> 
>