Re: Rad fan dosen't run after engine off !

["Arun Rao" <rao@frisbee>]

On Sep 1,  2:07pm, Steven Buchholz wrote:
> Subject: Re: Rad fan dosen't run after engine off !
> > OK, which is it?  My '82 Coupe's radiator fan is shut off when the ignition
> > is shut off.  Why drain the battery just to cool the radiator?  This would
> > make sense on a turbo if water is still circulated to the turbo.  Don't
> > some turbo models have a special water pump for this?  In any case the
engine
> > will just sit and cook because the water pump is not circulating coolant.
> >
> ... yup, that's it.  The newer cars have an auxiliary water pump that runs
> with the fan to keep the turbo's water jacket cool.  I know that it is used
> in '86- turbos, and that it was not used in '83.  There isn't much use for
> it on non-turbocharged cars of any vintage.  From what I have heard, al-
> though other manufacturers use water-cooled turbo jackets Audi may be the
> only manufacturer that has such a cooling system on their stock turbos.


	My '85 5KT doesn't have the water-cooled turbo (engine code KH
	doesn't have it, MC does), but the fan runs after shutdown. So
	does the injector fan, when it's really hot. What's more, my
	'80 Fiesta used to do it, and my '92 Accord sometimes does (both
	as normally aspirated as they come, of course).

	My turbo-diesel Volvo 740 didn't do it, but then it would have
	had to start up the engine to do so :-)

	Anyway, maybe there's more to it than meets the eye: I find
	it hard to believe that all these different manufacturers would
	find it expedient to build in a feature which is useless, especially
	one that probably costs money to put in and has zero customer
	visibility (audibility?).

	-Arun


--
Arun Rao
Scientist
Pixar
1001 W. Cutting Blvd.
Pt. Richmond, CA 94804
(510)215-3526