'85 rad in an '84 5kS

[Michael Spiers <mikes@specnet.com>]

Well, it worked!  I think.  The thing's in there anyways, made it all the way
to work (~35 mies) without leaking, guess I'm happy.  Never went and got the
correct shroud for the '85, just "modified" the old shroud to fit.  The only
main difference was the location of the hole in the shroud where the fill tube
from the overflow tank goes in, but a jigsaw cured that problem.  At first, the
hydraulic pump hoses hit the side of the new rad.  However, once the new rad
was properly seated, meaning once I got the mounting bushing/bolt on the bottom
of the radiator properly seated in the notch in the lower body, everything was
dandy.  Let the thing run for about ten minutes in the driveway, only had two
problems:
1)  The oil pressure warning light came on for the first time EVER in the
180,000 miles of the car.  Let me see if I know why.  The idle control module
on this car, when hooked up, makes the car run at 2,000 RPM's when it gets
warm.  This annoyed me, and Audi wants $325 for a new module (yes, it is the
module and not the valve, I stole the valve from the Quattro and the '84 still
reved high) so I just yanked the connector out of the idle valve.  Now, once
it's warm, the car idles at about 950.  However, when cold, it idles around
500, if at all.  I'm guessing that this low idle is the cause of the oil
pressure light coming on, because as soon as I drove it around the light went
off.
2)  There was a horrendous noise after about ten minutes of idling.  Popped the
hood, investigated, found that the support bracket of the hydraulic lines was
swung around the wrong way and the fan was eating it up.  At least I know the
sensors and the fan work!  BTW, on '84's at least, the side of the fuse box to
tap into is the side FURTHEST from the fender.  Not that I now have the lead
for my driving lights arc-welded to the inner fender because I had the wire on
the unfused side of the fuse box or anything, I just thought I might share some
information with the group.  Anyone with guesses about my oil pressure light?
 I really think I know the problem, but if I'm wrong I'd appreciate knowing
why!

-Mike
87 5000CS TQ