I am just doing research on everything to do with 4Runners before my import arrives. I had never heard of this type of fan before, but it makes sense.
Do Toyota give a definite refill value, or are there markings etc to show what the level needs to be?
Edit: I just saw this on an eBay ad of all places, but I don't know how accurate it is.
I checked if the O ring is available separately and it is not
Water pump for Toyota Hilux Surf GRN215W - Genuine parts