Tranny Temps

So some background, 2001 1st gen 3.4V6 A340E auto TRD Supercharged 4x4, 200K miles.

I have a Hayden 1678 plumbed in series pre-OE cooler in the radiator (fears of overcooling). The Hayden is nearly as big as an old school civic radiator lol. Thought it was overkill and for HD trucks hauling 5th wheels over mountains.

I got my trusty blue tooth OBDII running with the paid Torque app, showing me my tranny temps. Low and behold temps are low (130-160) in daily driving, traffic, work commute etc.

I did a nice canyon run on the way to wheel in Azusa and holly crap temps went up to ~215!!!! WTF!!!

Took the wifes IS250 for a little romp in a short hill run that gets my truck into the 200s for reference and the IS would only get to around 190.

What gives? Is it normal for our trucks to be on the hot side going up hill? Is my tranny making more heat than normal due to wear (200K original miles, TRD boosted)?

I'm thinking of re-plumbing the cooler to be post OE-cooler like the TRD instructions. If that doesn't do it there is always standalone configuration or upgrading to a fan/cooler setup. But I'm thinking something is going on with my tranny- maybe the flow through the coolers is much less than it should be, maybe my torque converter is putting out a lot of heat due to wear?

 

I don't know. Sounds like you are more knowledgeable than I am about trans temps and coolers, but I can tell you that my ultragauge tells me that my trans fluid breaks over the 200 degree mark when I am towing about 5000 pounds in drive (5th gear) on the interstate pulling pretty hard.

I do have the factory tow package which includes the tranny cooler.

 

Do you happen to know where the sensor is on my '12? Before or after the cooler?

 

I'm ashamed to say, but I don't know where the OE sensor is. Heck for the longest time I thought it was just a thermostatic switch for the dummy light, not an actual temp sensor feeding the ECU. If Toyota put it before the cooler/s then I think that is uncommon vs. the many other OE and aftermarket setup monitoring the return/pan- and if Toyota did that then that explains my temps.

I've been reading around that most OE setups seem to run about 160-180 consistently, and 160'ish is where mine hangs (80 degrees outside).

I think most OE and aftermarket installs are in the return or pan. The little I breezed over with 2nd gens, you guys seem to have two sensors and can see both return/pan and right after the TC which should be the hotest it gets. I think guys were showing about a 20 degree difference between the two sensors. Pretty cool to have two and to see the differencial.