The factory transmission cooler is a bit of a weird set up. It basically is
in parallel with the radiator. The goal was likely to provide cooling with
relationship to load. Flow will follow the thermostat. The down side like
the oil cooler is only has the warm engine coolant to begin with. In winter
the t-stat will remain throttled so little flow for the trans cooler. The
torque converter fins are doing all the cooling and with no t-stat there
will keep the transmission cool, maybe too cool. As the t-stat opens heat is
actually being added.

Dennis

-----Original Message-----
From: Vanagon Mailing List [mailto:vanagon@gerry.vanagon.com] On Behalf Of
Robert Clemmer
Sent: Sunday, June 28, 2015 9:01 AM
To: vanagon@GERRY.VANAGON.COM
Subject: FW: Auto tranny cooling

In my 91 2.1 wbx automatic I had the transmission shop weld a bung in the
transmission pan when they rebuilt the transmission.  I have no cooling
other than the factory coolant/oil cooler.  The temperature will seldom go
above 190-200 unless I get into stop and go traffic after driving at high
speed.  In the winter months it would be rare to see it over 150.  The
exception was this past week returning from FL.  The OAT was 100 -105.
Driving at 70 mph had the oil temps in the transmission up to about 215 and
the engine oil up to about 245.  Once it got that hot, I simply slowed down
to 65 and temps cooled of by 10 degrees or so.  This was the first time ever
I had the radiator fan come on high speed while driving in 24 years.   I
never see engine oil temps over 210 and transmission temps over 190 until
the OAT's are over 90.  In my humble opinion, the engineers damn good job.

Bob C