All,
I installed the missing thermostat on my TIICo engine.  I put an 80 degree unit in.  Here is what I found.

With the thermostat in, the engine warms up faster, just as you'd expect.  I found that the engine temperature stayed very steady on a hot weather run to Lake Placid NY (250 miles).  My temperature needle stays just over the led now.  The engine temperature went up a few times on long uphills, but the light never came on.  Once the hill was crested, the needle settled back to it's normal position.  Without the thermostat, the engine temperature would continue to increase until the light was blinking, and then stay steady at a higher indicated temperature.  Once the light was on, it stayed on.  The temperature never came back down again...until the engine was stopped.

The fan never came on when underway without the thermostat.  The fan operates normally now, with both low and high speeds kicking in when they are supposed to.  The fan switch was not changed.

I got a lot of responses about what a missing thermostat would do to the coolant temperature. In simple terms, the cooling system was designed to run with a thermostat installed.  It will not run optimally if it is missing this part.  Perhaps lack of water pump outlet backpressure, perhaps increased flowrate through the system (either could lead to cavitation). After my weekend trip, my experience is that a missing thermostat makes the engine run hotter.  Again, this is just my experience, and I'm not going to debate those who don't believe it.  

Bob
East Haddam, CT

~-----Original Message-----
~From: vgonman@earthlink.ne
~To: TiiColist@vgonman.com
~Subject: Fw: Aux Oil Cooler install...pertains to TiiCo
~
~
~Hey guys, I don't know if you were listening in on this thread 
~or not, but 
~I shot a message over to Frank G. (the guy who's building up a 
~turbo motor 
~for his V'gon using a combo of VW and Saab parts) to see what 
~he had to 
~say about the oil cooler thing. Here's his response. As soon 
~as I get time 
~