Re: What is the best Thermostat temp?

["Fred Munro" <munrof@isys.ca>]

    Take a good look at the Type 44 Audi's cooling layout. The rad is quite
small (certainly much smaller than the MB 200) and the air passage to the
rad can hardly be described as "direct". In warm ambient temperatures at low
car speeds, the system relies on the cooling fan to pull enough air through
the rad to cool the engine. If the fan does not run, the engine overheats
(BTDT). Given the system parameters, the engine will heat up until the fan
comes on, then cool off until the fan shuts off, and go through that
temperature cycle ad nauseaum.
    The thermostat is capable of accurately controlling temperature - in
winter the temperature on my '91 200q runs rock steady at 85 C because the
outside air is cold enough that the fan is not required at speeds above 5
kph. The coolant flow control provided by the thermostat is sufficient to
keep the engine at the design operating temperature.

Fred Munro
'91 200q  262k km

-----Original Message-----
From: Zsolt Kovacs <zsolt@telusplanet.net>
To: Brett Dikeman <brett@pdikeman.ne.mediaone.net>
Cc: Todd Phenneger <phen9461@uidaho.edu>; quattro@coimbra.ans.net
<quattro@coimbra.ans.net>
Date: Tuesday, December 01, 1998 8:43 PM
Subject: Re: What is the best Thermostat temp?


>This is my 4th Audi (this time an 86 5k CD tq) but they all did that. The
>temperature ranged between about 80C-110C depending on outside temperature,
and
>driving conditions. I am also curious to get an answer from someone with
more
>experience why that is. I had an old MB 200. Once it warmed up the temp
guage
>didn't move. Why does the Audi's?
>
>Brett Dikeman wrote:
>
>> I would definitely leave it alone!
>>
>> Cooler thermostats cause excess cylinder wall wear.
>>
>> Audi knows best with their engines.  Trust 'em, honestly!  Car
>> manufacturers go to great lengths to determine these things, much better
>> than we email-monkeys(sorta like grease monkeys, only we use email :)
>>
>> I think you've got a case of Fiddle-itis.  I'm a former victim.
Everything
>> in the car looks lousy or ill-designed by the OEM when one is afflicted
>> with Fiddleitis.  The noted exception is the GM A/C controller head,
which
>> about everyone who's seen it, wonders why the hell it lasted in the type
44
>> cars until 1991 and why it wasn't dumped after 2 years.  At least the
>> second-generation units(ie, after 1985-86) didn't burn up after a year or
>> two...
>>
>> Ugliest damn thing....ask anyone on the 200q20v list.  We desperately
>> wanted to figure out how to pop in an S6/S4 head...they look SO much
better.
>>
>> Anyone with a donor S4/S6 unit, please let us know.  Back-burner project,
>> but I think it can be done!
>>
>> Brett
>>
>> > I need to replace mine and am wondering what is the best all around
>> > te4mperature switch.  I drive in much snow in the winter but summers
get
>> > up to 100 degrees.  THis is for a 4kq.  Also, what should be used in an
MC
>> > turbo motor.  Same unit?  Same temp.
>> >       How much should these be?  THanks and sorry for the peddly
>> > questions.  L8R
>>
>> ------
>> Brett Dikeman
>> brett@pdikeman.ne.mediaone.net
>> ~)-|
>> "Diplomacy is the art of telling someone to go to hell and making them
>> happy to be on their way." - Mark Twain
>>
>> "Oh no.  Not again." - The bowl of Petunias
>>
>> "... it is important to realize that any lock can be picked with a big
>> enough hammer." -- Sun System & Network Admin manual
>>
>> Statler: "Hey, this one sounds cute."
>> Waldorf: "You old fool, that's not the personals, it's the obituaries!"
>> ------
>
>
>