Question about wheeling with an auto transmission

I have a 02 TRD Double Cab, with supercharger and URD 7th injector upgrade. I have been trying to find out how to keep my transmission temps low while offroad. I am getting my readings from a scan gauge II (SG) which I have head but would like to confirm that the SG reads about 10-15 degrees hotter than the actual "system temp". The first few times I took my truck out after I got it I was getting SG temps of around 200-220 degrees (ambient temp was around 75-95 degrees). Subtracting the 10-15 degrees that would mean it was running around 185-210, which in my opinion is still a little hot. So I checked the temp of the outlet on my B&M 70264 cooler with an infrared thermometer, and it read 150-160 degrees. After this happened it was suggested that I run the transfer case in 4lo while offroad. So on Sunday I tried this and the temps stayed really low (granted the ambient temp was much lower, around 45-65 degrees) I think the max trans fluid temp I saw while offroad was 160 degrees. On road going up hill was a different story as it climbed to around 208 degrees at one point doing on highway driving (not in 4wd). I am wondering if I am doing more harm than good driving around offroad in 4lo all the time, most of the terrain does not call for it. I had the transmssion in any one of the three positions (d,2,1) depending on the sitation at hand.

I am wondering it someone can give me some advice on driving offroad in the desert with the setup I have and how to keep the temps low without tearing up my transmission, transfer case, or differntials both on and offroad in mountainous/steep terrain.

Also is there a way to tell if the differential fluid is bad? I think I put all the details in here but if there is some info I am missing please let me know.

 

Auto is better for rock crawling, easier anyway.

Also if you are if 4lo, there is less stress, since you aren't spinning your wheels at 70 MPH. However, more torque in 4lo. But shit, the tranny has a hot temp light for a reason, it comes on, then you shut off your truck.

 

so I should just put it in 4hi, tranny in D and goto town until my temps shoot up? lol

I would like to do the 2lo mod, but I dont know if that is even possible since I have a J shifter TC

 

Someone on here, I can't remember the thread right now, found documentation about what temp triggers the "too hot" fluid warning light in the v6 auto tranny. IIRC the temp threshold was 250*F. That seems quite high to me but I've yet to see temps higher than 225*F in what was fairly severe conditions last summer.

Curious why you say the SG reads high. It is pretty darn accurate in all its other parameters. Why would it be so far off in tranny fuild temps?

 

Quoted from another forum post I had regarding high ATF temps:

 

After readiig that quote, I still wouldn't come to the same conclusion you have.

Having the pickup point for the sensor at the hottest point seems like a good thing. The whole idea is to know what you are up against. Lets say the sensor was located at a point after the fluid cools off in the radiator, how would that help you to know if you have exceeded or are about to exceed the system design parameters? Isn't what you really want from the SG?

 

install an extra tranny cooler in front of your radiator, works great for offroading.

 

I need to run two coolers, instead of just the one B&M 70264?

 

No. Just install bigger heat exchanger on your existing tranny cooler.

 

I thought the one I got was going to be big enough, guess not. Thanks

 

Compare temps with other scanguage users. If the sg is reading false temps i would return it.
Does your at light ever come on?
Have you changed your tranny fluid lately?
Maybe its time to drain and fill a few times. Could be the reason temps are going up.

 

Or you could install a puller fan on your existing heat exchanger to help move air through at slower speed. Can you post how big is your existing heat exchanger?

 

I did a flush and fill about 1500 miles ago. The AT light has never came on. I think the temps the SG is giving me are correct. Normal driving yields lower temps (norma average temps).

I have a pusher fan on my B&M 70264 cooler which is pretty beefy at 11" x 5-3/4" x 1-1/2" this model is rated at 14,400 BTU

I thought when I bought the damn thing it would be plenty to cool the fluid.