RE: carburetor-low audi content!

["Buchholz, Steven" <Steven.Buchholz@kla-tencor.com>]

... I know next to nothing about carburetted VWs, but I did have a similar
problem on my wife's old Toyota Celica.  What happened was that the vacuum
port on the primary venturi had a problem when the venturi itself worked
loose.  The venturi was a separate part from the main carburettor casting,
and was staked in place by a brass tube that provided vacuum to some other
circuit.  Over the time with the vibration the soft brass tube wore away,
making the venturi loose in the casting.  The vacuum circuit was internal,
so rather than fixing it I bought a Weber carb that was smog approved.  The
nice mechanically coupled secondary worked just fine!

This may well be the problem with your carb as well because I had a very
similar problem on my fuel injected 1978 Audi Fox where the EGR circuit was
controlled by a vacuum port in the primary throttle body.  To get a good
enough vacuum signature Audi stuck a venturi into the primary and held it in
place ... with the soft brass vacuum fitting ...

My fiendly Audi dealer "fixed" my problem with the engine stalling when cold
by blowing a hole in the diaphragm of the vacuum multiplier with compressed
air.  I never found out about it until years later when the smog check laws
got more strict and I replaced the vacuum multiplier to get the EGR valve to
work correctly ... the car started stalling immediately.  I disassembled the
old unit and found that a hole was popped in the diaphragm at one of the
ports.  

Funny, I just recalled that this is exactly the same dealer that "fixed" the
AM reception that was lost after the first attempt at the airbag recall on
the V8 by swapping the front and rear antennas ...

... sorry about going off on a bit of a rant there ...

HTH!
Steve Buchholz
San Jose, CA (USA)

> ----------
> From: 	mamn97@dial.pipex.com[SMTP:mamn97@dial.pipex.com]
> Sent: 	Monday, January 04, 1999 3:30 AM
> To: 	quattro@coimbra.ans.net
> Subject: 	carburetor-low audi content!
> 
> l've been tring to fix the carb on my parents  1800 vw . The 
> problemm is that the second valve failes to open when u put ur foot 
> down - due to the lack of any vacuum in the vacum tube operating 
> the 2nd valve. I originally thought that the vaccum pipes were wired 
> incorrectly , but as far as I can see it's how the diagram has it. The 
> diagram says to conect it (the pipe operating the device operating 
> the 2nd valve) to the the small chanel running from the barrel of the 
> 2nd valve. But surely presure isn't being generayed from this 
> channel since the valve isn't open? Besides, this channel seems 
> tiny to generate nearly enough pressure. I've also tried using a bike 
> pump to free this chanel assuming that it's clogged up but still 
> absolutely no pressure.
> Any ideas if my wiring layout is incorre\ct? The cars done 140k and 
> is running extremely well / smmooth. Do u know if it's a common 
> problem and a new weber is needed? the car iss a '89 gl model.
> 
> ps . thanks to the replys for my post on  control arm bush 
> replacement on my audi - greatly appreciated, btw, what does btdt 
> mean?
> pps. the reason i write to the list for advice is that it's the identical 
> engine/carb used on many european audis. 
> 
> cheers,
> 
> Ed
> Manchester
> 
> David Shiers 
> West Midlands IRIS Initiative
> work 01538 381022   
> home 01538 399660
> fax 01538 398638
>