[urq] That Pesky Vacuum - Was Helicoil

[Martin Pajak]

Hi Andrew,

Wow... sorry to hear that a good gas cap coused your tank to implode.
You have two choices, use the original system and have it correctly
plummed into the intake track (not manifold), the maintenance docs on my
site will have the routing.
Or see how the new engine does it (not sure exactly which one you have).
I know 7A has couple of fuel evap solenoids which cycle depending on
conditions, mainly at idle.

Cheers
-- 
Martin Pajak

http://www.quattro.ca

1982 Audi Ur-quattro, SQ project
1983 Audi 80 quattro, Euro 2-Tür
1984 Audi Ur-quattro, The new project 20vt
1993 Audi 90 CS quattro, das new wintervagen

> AF
> So, thanks to all who offered thoughts on the spark plug helicoil. I had a
> track mechanic tap the head and install a steel insert. Worked like a
> charm
> and I was back to driving after installing a new plug and new coil over
> plug
> (which got burned up by the exhaust gasses). 1 session later I was back in
> with a misfire, this time in another cylinder in the ABZ. Well, another
> plug
> was finger tight and had lost an electrode or two. I replaced all 8 plugs
> just to be sure. I found another 2 that were finger tight. So someone
> noted
> tht lean conditions can result in this kind of damage. Righty-O. Seems
> that
> the sillisest things cause problems.
>
> My gas cap has always leaked gas since doing the engine swap. 2 new caps
> later and still no solution. Martin kindly sends me a known good one, and
> boy was it a good one.  I started the car, drove 2 miles and head a loud
> pop. Thought nothing of it. Drove on the highway and found the car was
> occasionally surging and cutting out, but not totally stalling. Seemed
> like
> a fueling issue. Pulled over, pulled the gas cap and I could barely get it
> off, the vacuum was so strong. Fast forward 24 hours and I find that the
> gas
> tank has collapsed, at least the top has caved in under vacuum. Seems when
> 2
> bennett did the swap, they did not correctly hook up the tank vacuum line.
> It was not vented at all.
>
> So, this might have caused the lean condition...
>
> Questions: Can I pressurize the tank to push it out or is that too
> dangerous?
>
> Anyone have a spare tank they'd be willing to sell?
>
> Can someone tell me where the stock tank vent line goes on the UrQ (to the
> instake, or a carbon canister?)
>
> Thanks so much.
>
> Andrew Finney
> 1985 UrQ V8
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