[s-cars] After-run Pump

[Wayne Dohnal]

I went through the same thing and know exactly how you feel.  When I got the
car the pump was shot.  I replaced it but never heard it run.  I did the
short-the-sensor test and it worked fine.  Then on one fairly warm spring
day I went out to the garage a few minutes after I came home and this fairly
muted sound came from the car.  When I realized it was the after-run pump
(really the fan because the pump doesn't make much noise) I was so happy
that it was working!  It ran for 30 seconds max.  My conclusions since then
are:

- It runs only on warm days.
- It doesn't run until a few minutes after you park the car.  And not for
very long.
- If you're not right there at the right time you'll never know that it ran.

I though of hooking up something like a turbo timer to run it for a while
every time it is shut down.  But I also realized that of the many quirks
with our cars, turbo failure isn't one of them.  It appears that Audi put
together a very robust turbo system.  So I reverted to the 'if it ain't
broke don't fix it' philosophy.  Maybe with my good intentions I'd be
shortening its life by cooling it too fast some of the time.  Of course it's
possible that your sensor is really broken.  You'd probably have to pull it
out to test it.

Wayne Dohnal
1994 S4

>I have never heard the after-run pump on my car and I suspect something is
>amiss wioth the thermostat that makes it run.  It does run when the temp
>sensor is shorted, so the pump is fine.  Anyone know if it is just the
>sensor or something else.  Any Ideas on troubleshoting?
>
>I had another thought, does anyone know if the after-run pump circuits can
>be modified to run for a set period of time after each shut-down rather
than
>just when it gets really hot under the hood?  Does the realy have a timer?
>Could it be as simple as shorting the wires and letting the existing relay
>control the time.   It might be hard on the battery though.  Anyone ever
>tried this?