[C320-list] Deck filler O-rings

[Dennis Cookson]

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