silverd2

I believe there's a member here who did that (or previous owner/mechanic)...said he ended up pulling (changing?) the tank I believe.

I'll take you up on that beer (or ale)...may be dreaming, but really hope to do a return visit sometime.

Cheers,

Sam

BrianC72gt

Good to know about the hose clamp ... smooth and stainless...good stuff. That larger diameter plastic hose on top that you re-secured is from the fuel filler inlet. When you fill the tank, it directs the fuel into the fuel pump reservoir/cup to prime the pump. So, let's say you are on empty...and only put in two gallons. Rather then have a dry pump labor to suction fuel off the bottom of the tank, the primed pump is wet and starts pumping fuel immediately while replenishing...eventually...through the suction hoses.

When I removed my fuel pump, the bolt just kept spinning and I ended up making up a foot long hole saw and cut the whole assembly out after draining the fuel and filling the tank with 22 gallons of water. This was back 7 years ago, before you could readily purchase the pump on its own. The pump from my dealer back then was $500 but it included a complete plastic housing.
I know a few others who ran into the same problem that dropped the exhaust, rear sub-assembly, the tank and replaced the whole shebang...very spendy. Mine cost me two beers an some brain cells (I drank the beer). This tank is proof the germans never forgave the rest of us for the war.I swear they do it just to screw with us.

twentysevenlitres

Follow up:

OK, been through two tanks now.
The S8 is running great.
I ran the first tank down to almost empty to prove everything was mounted correctly. So no drama's there.

After the first day, I initially had that same fuel air squeezing sound in the lines I tried to describe in the original post.
I had done a silly thing after my pump housing hose repair - on seeing the hose appear a little bit squashed under the clamp, I slackened it off a bit.
Amateur mistake!
I had to pull the pump back out of the tank mounting hole and play for 20 mins with an 8mm spanner to get it tighter again...(I left it all attached internally with the big long bolt (didn't want to go through that again) and just pulled it up about 30-40mm - it was enough, just)
That fixed the air squeezing sound!

I also had a smell of fuel on first fill to the top. I correctly surmised the culprit to be the sender cap seal (the one o-ring they don't give you in the pump gasket kit).
Apparently the o-ring seal and cap used to be a $15 item from Audi. Now it's $50+!
Nothing wrong with my cap, so I took a guestimate measure en-situ and went to my local bearing place and grabbed 3 o-rings in the vicinity of the right size (they were imperial, but had a cord diameter very slightly thicker than the worn metric OEM jobby).
Went home, removed the sender cap (again...) picked the best fit o-ring of the 3, applied some rubber grease (great product - highly recommended to be used in moderation!), put it in place and put the cap back on.
No more petrol smell.

Job complete!