FW: Older 5K Waste Gate Diaphragm fix/substitute

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

... as it appears that the sources for replacements are few, I thought I'd
repost a message I got from the list and tucked away in my archives.  I've
never experienced the condensate that the poster complains of, nor have I
tried to do this myself ... I thought it might be interesting in the event
that I ever lost a WG diaphragm ...

If anyone was interested I suppose they could contact the original poster to
see if the thing is still working in his car as it is now almost a year
later.  Frankly if I knew I could replace the diaphragm for next to nothing
and have it last a year I think I'd do it ... it isn't _that_ difficult to
disassemble the WG ...

HTH!
Steve Buchholz
San Jose, CA (USA)

----------
From:  superba [SMTP:superba@pacbell.net]
<mailto:[SMTP:superba@pacbell.net]> 
Sent:  Tuesday, May 19, 1998 9:35 AM
To:  Quattro
Subject:  Older 5K Waste Gate Diaphragm fix/substitute

Hi All,

I've already explained that I'm not a regular subscriber in an earlier
email.
Like many other turbo owners, my waste gate diaphragm deteriorated severely
due to condensate collecting in the upper bell housing.  The last time I had
it off, about 18 months ago, it looked so bad that I simply couldn't put it
back.  So, I looked around for a substitute, even contacting Bendix Air
Brake, trying to get some air brake diaphragm material.  It probably would
have worked but I couldn't con anyone into giving me a scrap to try.  So, I
took a piece of an inner tube(from an old truck tire), used the upper cover
of the waste gate as a template, drew it out and cut a diaphragm out of the
inner tube.  The only tricky part was to draw lines through the 6 mounting
holes with a pencil and a straight edge, which established the center point
and the placement of the mounting bolts.  I provided for some slack material
for the flexing of the piston by extending the hole marks outward by about
1/4".  I used a leather hole punch to punch the center hole and the mounting
bolt holes.
When I installed it, I expected it to tear up, burn up, or just die a
premature death.  I ran it for a while, opened it up and looked at it and it
looked none the worse for the wear.  I tried several fixes for the
condensate;  my 5K turbo came with the upper bell housing vented to the
engine compartment which I thought to be causing the condensate.  I tried
venting it to the turbo inlet, and later to the inlet of the air filter;
neither of which reduced the condensate.  I also tried turbo feedback by
venting the pressure from the large tube that contains the over pressure cut
off switch(it grounds the fuel pump relay under normal usage).  Turbo boost
feedback provides amazing boost and a real burst of power.  However, I
wasn't too eager to exceed my BMEP or blow oil so I removed this after
trying it for a short time.  I suppose that one could become accustomed to
the extra boost and drive prudently and accordingly.
On May 17, 1998, I opened up the waste gate to inspect the diaphragm
expecting it to be in shreds and it seemed just as intact as it was when I
installed it!!  Except that it literally contained about 8 ounces of
condensate which ran out as I opened the housing.  That prompted me to
remove the vent to the air inlet which had caused more, not less,
condensate.
However, my trial shows that almost anyone can replace their waste gate
diaphragm with a little time and effort and a scrap of inner tube.
Direct any questions to me at superba@pacbell.net
<mailto:superba@pacbell.net> .
Cheers!
Jim Jordan
MCSE, MCT, MCP+Internet
81 5K Turbo/290K