Sadly I just rummaged for parts in my basement and never measured the o-ring. If you look at my master thread on fuel system diagnosis I may have taken a pic with my calipers to show the size.

The size is certainly metric and a standard size you could buy at a hardware store. I had some flashlight o-rings like 18-19-20mm in my basement I thought it was one of those but the other seal is about 27 it could be in that range as well. If nobody beats me to it I'll get a measurement the next time I take apart one of these.

I already did both mine and wife's but I will do the siphon refurbish on any BMW before about 4000 hours


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2011 E70 • N55 (me)
2012 E70 • N63 (wife)