I always try to do a little research before I post something as fact.
As do I, as do I! Only I think more than a little research is in order here, in this case. I have actual pictures with the pan off demonsrtrating the the temp sensor does not pass into the sump, at all. It never even extends out of the valve body. The sensor is taking its "sump" tempertures from the valve body circuit, not the oil in the sump. The four images are as follows, 1) Picture of range sensor electrical connection where it enters the transmission (the lime green electrical connector); 2) Valve body from same side as where range sensor is located (notice the absense of any sensor tip passing through the valve body; 3) Valve body from directly below the location of the range sensor and integrated temp sensor. Note: the bolt holes around the rim of the tranny are for the oil pan, the black bolts hold the valve body in the transmission notice the absense of any protruding device(s)
; and 3) the manual's image of the integral range sensor and temp sensor as it would look removed from the transmission. No where does the tip of this thing protrude out from the valve body and into the oil pan (sump).
If you still believe that the temp sensor is taking the reading from the sump, why don't you take the valve body assembly with range sensor and oil temp sensor as you show in your post (above) and flip it over and point with your finger where you believe the sensor is protruding out of the valve body and down into the sump oil? Your picture just shows the sensor as it sits on top of and engages the valve body itself, nothing more. My pictures clearly demonstrate it does not penetrate beyond the valve body.
I found another thread/Internet article quite some time ago when I was reseraching where the best locations for tranny temp sensors should be located since many there were many different opinons on the subject. Turns out, for any automatic transmission, the absolute WORST place to test oil temp is from the pan, especially from the drain plug area where a lot of guys think is a great place to get temperature readings would be. The author of the article was an engineer very valmiliar with fluid dynamics and extreamly knowlagable of automatic transmissions. If I ever find that article, I will download or re-post a link. This engineer said that, due to the volumn of fluid in the pan, temperatures are very slow to react to temperature on a whole is never an accdurate read of what the operating temp actual is inside the transmission while it is running. The best place for the back-yard mechanic to get an fairly accurate transmission reading is of the oil as it leaves the transmission. In other words, the oil in the cooling line right after it leaves the tranny, but before it gets to the cooler (OEM or auxilliary), the closer to the trasmission exit port, the better. That is how HOT the fluid really is getting and what is "felt" or experienced by the majority of the transmission internals, not the oil in the pan, and certainly not the oil in the return line.
The reason I have one sensor on each side is to measure the differential and effeciency of my cooling system (OEM and auxilliary tandem). The cooler the oil is coming back, the cooler it will be on exit (so goes the theory. If your happy with just taking sump temps, good for you, but I, for one, want to know how hot the oil really is getting.
I forgot to say thanks for sharing the article on the mechanical fan option. So thanks, It was a good read! Still think I will have problems with my intercooler piping not clearing the fan, or the shroud for that matter. May just end up with a Derale Hyper-Cool remote cooler mounted in the rear, and bypass the OEM tranny cooler and my B&M aux cooler altogther.
Clearly, you are very lucky to have such low tranny oil temps, even with my deep sump and aux oil cooler, I still experience temps approaching 200, but at least not the 270 I saw before all that. I may still add a remote cooler. I really like the Derale Engine Oil Cooler and I mounted it in the passenger side wheel well. Don't think I have room for the another one on the driver side which is why I am looking at the mechanical option as another approach.