Not to hijack, but this may help...
Since I got the trans rebuilt (picked up the truck yesterday) the trans has been running at 220 deg in moderate traffic/interstate.
Before the rebuild it was normally at 160-170 degrees???
I followed the instructions from the link posted above and my bypass works fine...I also flushed the cooler which was clean, and ran the test again. Still fine. (36 oz for 15 seconds, nothing out of the rear port) trans temp was at 150 durring the test.
Drove it a few miles, and back up to 210 it went...I stopped at a trans shop along the way. The owner and I took it for a test drive. he sais he blocks off the bypass when he rebuilds a 4r100, it isn't needed.
He also used an infared temp gun on my cooler lines. Gauge said 210, inlet and outlet lines at the cooler were 180, at the trans they were both 193. That dosen't make much sense to me...Im seriously thinking of blocking the bypass and adding 6.0 cooler.

 

typically you can 80 to the outside temp and you should be close. i usuall run around 160 and have hit 190 pulling a load.

 

Here is the answer to your question. You have a 99 acording to your sig. The 99's did'nt come with an O-T-A Oil to Air Cooler. When I installed my woods tranny I went to ford and boughta '00 radiatiator with new cooler lines to run to the new built in OTA. John says you must do this when you own a 99. My numbers before the OTA were 210/220 with the OTA and 6.0 cooler in One hundred and teen temps I never see above 180 degrees. You should be running 180 thru 210 that is considered normal tempature operating range. Get a new radiator ASAP IMHO
Hope this helps.
I did the blocks offs because my bypass valve clogged causing me to burn up my old tranny.

 

I did read that I need a 2000+ rad for the bypass block. You are correct.
I parted a 99 that had a new rad in it, I thought I saw the ATO fittings (blocked off) on the rad when I pulled it ( I cant remember) I'll check out my parts pile tomorrow and hope for the best.

 

Not necesarily for the bypass, thats a personal preference, but sounds like all you need is a cooler line. I'll check and see if I still have the P/N#'s for you. Also don't forget the magnafine filter I swear by those.

 

I wouldn't block the by-pass Frank. If the cooler plugs up, the trans is shot with no by-pass.

 

I'm on the fence.....at this point I dont know what to do

 

Its really 6 of one or half a dozen of the other. Like I said persenal preference, I lost my tranny to a cloged Bypass valve.

 

Why would you want to run fluid you are trying to keep below 160 through a heater (radiator) that runs at 210.

 

That a great question. You would think that the 210* coolant would heat the trans fluid, but I have read that the radiator never heats the fluid, it always cools it.
I guess I dont understand the fundimentals of it all.
Im guessing the trans fluid is hotter than 210* when it leaves the trans, the OTW cooler should in theory knock the fluid down to 210*, and the OTA cooler will cool it down to yet a lower temp before it returns to the trans.
So if thats the case, what temp is the gauge port reading:
1 The incoming (cool) fluid temp ?
2 The outgoing (hot) fluid temp ?
3 The inbetween (average) temp?

Maybe Mark will chime in.

 

I thought the same thing too..lol I have a hard time trying to grasp the theory of that concept.. hot fluid run through a cooler surrounded by another hot fluid cools it how??

 

The coolant in the bottom of the radiator is going to be considerably cooler than 210, figure around 160 or 170. You gotta realize coolant flows from top to bottom, so at the bottom it has radiated all the heat it can.

 

I knew I was gonna feel stupid for asking that question...
Great answer, Thanks. it makes perfect sense.