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Re[2]: 5KCSQ Turbo After-run Circuit/Thermo Switch



Thanks for the reply.

Dealer list is $28.35 and I can get a 10% discount.  After several 
$20-$50 hoses and other components, I'd hate to replace the switch if 
it is OK.  

I understand that the switch is supposed to come on at 110 Degrees C 
(230F) which is hotter than the radiator fan thermoswitch of around 90 
Degrees C.  So I hypothesize that I've just not been running the car 
in conditions that get the latent engine temp up as high as the 
switch.  My driving typically is just far enough to get the fan to 
come on and then I park.  I have yet to get stuck in gridlock on an 80 
plus Degree day.

It would be ironic if both the switches as I swapped from the '86 are 
defective. There is no question that the system comes on if I bypass 
the switch.

How would one test the switch - Heat up antifreeze on the stove with the switch 
in it while checking continuity?  Sounds dangerous!

I'll probably end up breaking down and getting the dealer switch for peace of 
mind, but appreciate others experiences on this.  The system certainly does not 
seem to be functioning exactly the way various literature (BENTLY / SJM 
Auto-Technik) describes.

Regards,

Ben 

______________________________ Reply Separator 
_________________________________
Subject: Re: 5KCSQ Turbo After-run Circuit/Thermo Switch
Author:  wallace@remdesign.com (Wallace White) at SMTPGATE
Date:    5/12/99 11:56 AM


Ben -

To your last question: yes, the system comes on a lot of times after 
driving. It usually comes on 30s or 1 min after shutoff (coolant temp 
does rise after shutoff) and runs for a couple of minutes. Long run 
times usually indicate a bad pump--but perhaps your dead thermo-switch 
(or whatever's wrong) has kept your pump from running so long that it 
actually still works.

That's very interesting, that the fault appears to be with the 
thermo-switch. I haven't heard of that being a typical failure. Can you 
check continuity across the switch? Should be completely open then 
completely closed. I don't know off-hand what the threshold temperature 
is supposed to be, but it corresponds to about 12 o'clock on the temp 
gauge.

If you do need a new one, you can always call The Parts Connection and 
get a more reasonable price. How much was dealer list?

- Wallace
  '87 5kcstq 154k

BSWANN@arinc.com wrote:
>
> Greetings,
>
> I recently aquired an '87 5KCSQT Wagon.  I have been observing that 
> the after-run circuit Fan and Pump does not seem to come on in my
> daily driving, which only occasionally gets the fan to kick on when 
> the car is at slow speed or parking - temp guage needle right in the 
> middle vertical.  I have not experienced any severely hot days yet,
> but want to make sure I don't have a problem leading to a cooked turbo 
> as summer weather approaches.
>
> I bypassed the Thermo-switch by connecting the two wires together, and 
> the system operates - both fan and pump.  My local AUDI dealer wanted 
> some crazy amount for this switch, and did not stock it -- we weren't 
> even sure if they had the right part no.  Since I have an '86 CSQT not 
> yet on the road, I swapped the Thermo switches.  I still have the same 
> results.
>
> Question for the collective experience of this great list:  Should I 
> always be expecting this circuit to kick on after I turn the car off? 
> Is this something that only would occur under severe driving
> conditions on a hot day stuck in traffic and then turning the car off. 
>
> I'd rather not purchase non-refunadable electronics parts at dealer 
> prices if the switches are really not defective.
>
> TIA for your replies. In the mean time I let the car idle for 40 sec 
> before shutting off.
>
> Ben Swann
> '85 4ksq
> '86 5kcstq (parts/rebuild?)
> '87 5kcstq Wagon

--

 Wallace White                             wallace@remdesign.com 
 REM Design                                     tel 415.621.3922 
 290 Division St., Suite 401                    fax 415.621.4024 
 San Francisco, CA  94103               http://www.remdesign.com