Thermostat Information

[QSHIPQ@aol.com]

In a message dated 97-01-24 13:48:03 EST, you write:

<< Ho hum.  Is the "thermostat" issue also dead?  I'm still waiting for 100c
water 
 temperature part numbers for any engine, and oil thermostat part numbers for

 the WR, GV, WX, MB, RR and KW engines?
   >>
Hardly Phil, hope this helps you some.  Thanks for the reminder.  Audi lists
the following part #'s for your information, 2 wire interchangeable to 2
wire, 3 to 3.  Here you go:
035-121-113        80C thermostat
035-121-113B      87C thermostat - MC

The Fan switch choices are as follows:

AUDI PN             APP

321-959-481E     2-pin  95-84C
823-959-481D     2-pin  82-77C
823-959-481E     2 pin  70-75C
823-959-481F     2-pin  92-87C
811-959-481       2-pin  95-90C  (86-87 coupe)
321-959-481       3-pin  93-88C/85-80C
321-959-481D    3-pin  102-91C/95-84C

ALL oil cooled audi applications list 100c as the only oil thermo
application.  For Phil's peace of mind let me write this, THERE IS NO 100c
THERMOSTAT.  My post is in reference to the optimal operating temperature for
the audis being 100c.  Phil interpreted this to mean there is a 100c
thermostat, there is not, apologies to anyone that got that impression.  My
advisory is that you be careful running a cooler thermostat, all the above
are listed as specific car applications.  You can see that if you put the 80c
water thermo in a car with a 959 481 3 pin switch, you could have the fan
operating before the thermostat is open, not good.  

If you mess with these, understand: 1) you may not pass emissions, 2) you may
not increase the perfomance of the car, 3) your gas mileage can go down, 4)
you can get oil blow by on an MC motor rings in the winter.  My suggestion as
posted, would be to leave all the thermostats as stock, increasing the size
of the radiator or the oil cooler as the way to address heat issues.  If I
need to be more clear in the above, please do post.  

As for reference to 100c....  There are currently 2 schools of thought
regarding engine operating temperatures, 1 favors the 75C approach to oil,
since that is where the Viscocity index is usually referenced, and the 2nd
references the 100c approach,  75 is not enough to release the moisture
(water) that collects in the oil from heat cycles.  Audi designs it's motors
with the second approach in mind.

Any corrections or additions gladly accepted.

HTH

Scott