rad fan behavior

[Huw Powell]

> I haven't been able to find any documentation which states the correct
> behavior for the radiator fan in an '85 4000s quattro.  Here's what mine
> is doing:
>
> 1. Coolant temp is high and radiator fan is running.  I turn off the
> engine - radiator fan immediately stops.  Shouldn't it continue to run
> until the coolant temp has dropped, even with the engine off?

that is normal.  there are two completely separate circuits running the
"engine on" and "after-run" radiator fan.  although, as some have said,
your '85 might not even have the afterun setup.

The after-run sender is on a bracket mounted to the two rearmost cam
cover studs.  pull the wires and short them (if it is there), if the fan
runs, you've just tested everything but the sender.  pull the sender,
attach the wires, and drop it in boiling water to check the sender
crudely...

>
> 2. When the car is first warming up in the morning, and coolant
> temperature is starting to climb up to normal operating temp, the
> radiator fan flicks on and off repeatedly sometimes, until normal
> operating temp is reached.

that's not normal, you might have a faulty sender in the radiator.

> 3. The radiator fan is very loud compared to later model cars.  Is this
> normal?  Is there a quieter fan from a late model Audi that will fit (or
> that can be modified to fit) a 4000q?

hurricane only... I think there are three and five blade fans that were
used there, can't remember what is in my coupe right now, or what
year/model it came out of, but I can hear it with the radio off and
windows closed, but not too loudly.  Yours might also have a chipped
blade which would make it louder.  or a noisy motor...

--
Huw Powell

http://www.humanspeakers.com/

http://www.humanthoughts.org/