Replaced my Racor filter but forgot where the old 1" rubber O Ring was installed. So, am looking for a home the new 1" ORing; It fits over the center post of the bowl at the bottom but doesn't look like it would serve any purpose there. I wound up putting it on the downward pointing threaded post at the enter top filter mounting seat; joining the larger ORing that fits on the top of the filter itself. It doesn't look like it's posing any problem there although it took forever to repeatedly hit the air purge until the engine would continue to run without stalling. I could not find any information on this mystery ORing on the internet. Anybody?
Is this what you Have
The small O Ring on Racor Fuel Filter and clear bowl. - YouTube (https://youtu.be/NbTdKyMgy-g)
The gasket placement by the guy in the submitted video link is not consistent with the Cummins manual. According to the text and illustration in the "ISM Series Operations and Maintenance Manual" Schedule A, Pg 4-2...the small O Ring is called the Thread Adapter Sealing ring and is placed on the thread adapter. Here's a photo of a thread adapter (not the actual one on my FT) Thx to all who tried to help.