afterrun coolant pump

Phil Rose pjrose at
Fri Oct 2 09:06:21 PDT 2009

Actually, I believe the afterrun relay has a specific "heat soak" 
time of 5 minutes (more than "a couple") before it can turn on the 
fan and pump. I find that my car's afterrun fan speed is so low (and 
quiet) that you can be unaware of its operation unless you're paying 
attention and also standing fairly close by. As George states, the 
running cycle is  fairly brief. If the engine is really hot and the 
ambient temp is also hot (i.e., summertime) the 1st afterrun period 
may be followed by additional "on" cycles. On the other hand, if it's 
wintertime--or even if you simply pop the hood open in moderately 
cool weather, the engine cools down so fast  (i.e., naturally) that 
afterrun is not triggered.


At 8:35 AM -0700 10/2/09, Gsidman wrote:
>On the '91 200 20v the coolant pump and the fan should come on couple of
>minutes after shutting off the engine, and both should shut off
>automatically after a few minutes.  Otherwise the pump should not be running
>at all when the engine is running. Apparently it takes a couple of minutes
>for the heat soak to build to the point that it trips the sensor.
>I have installed an over-ride switch with a timer relay so that when things
>are really hot I just flip the switch when I shut off the engine, and the
>fan and pump come on immediately and go off after five minutes.
>George Sidman
>Chairman & CTO
>WebLOQ, Inc.
>2801 Montery Highway
>Monterey, CA  93940
>Office     831 372-2600
>Mobile    831 601-1776
>200q20v mailing list


Phil Rose.....Rochester, NY USA
'06 A3q 3.2 V6 (20K, silver)
'91 200q	(165K, Lago blue)
Gone to Audi Valhalla:
'91 200q   (Tornado red)
'89 100 (Bamboo gold)

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