My truck is used for a plow truck in the winter. I take extreme caution in trying to do as much maintenance as possible. My problem is this. Normally when it is cold out my tranny temp gauge docent move very far from 100 degrees, but three times this weekend it has came up and slightly went past the 210 degrees mark. It takes a while to do this but it does happen. Each time I would have to stop and let the truck idle to bring the temp down. The trannys is a two year old ford rebuilt job with about 30,000 miles on it. I have drained the fluid in the pan once and dropped the pan and did the filter and fluid once. Those have both been done in the past six months. I haven't drained the fluid out of the torque converter because I didn't think that was possible without taking it out, and I figured that the new fresh fluid would work it's way in there. Am i wrong on that? I bought a larger tranny cooler to install but then I got to thinking that when I am not plowing I am going to be running the tranny to cold. Is there a way to put in some valves to only open the cooler when i am plowing? Or should I put a electric fan on the radiator to help cool? But then I am worried about cooling the engine to much. I have also seen tranny coolers with fans on them like in summit, is this a good option? Any help or suggestions would be great. Sorry about the long post I just wanted to give the whole picture. Thanks

 

What year is your truck? IIRC mid 2000 is when Ford added the OTW cooler in the rad. If you dont have one just adding a radiator with the cooler will be a huge help at slow speeds (plowing) The fan will keep air moving thru the cooler at idle. A new radiator is under $300
There are coolers with thermal bypass valves.
Here is an
example.transmissioncoolers.us: Tru-Cool MAX transmission cooler with external thermal bypass
I run the same cooler but without the bypass. I would mounted it directly in front of the engine fan for cooling at low speeds.
Someone can correct me, but I think till mid 2001 the TC's have a drain plug. If yours was rebuilt, It may have a newer design without the drain plug?

 

I have a early 99 F-250 Ext. Cab 4x4 with the 7.3. You are saying put a fan on the radiator or put a extra cooler by the fan?

 

The tranny is a ford reman with all the update's or so they say.

 

E99's don't have a trans cooler in the bottom of the radiator, your cooler is only efficient when the truck is moving. You could add a cooler like the one in the link I posted, and mount it in front of the fan. And/or add a OTW radiator. Both will provide trans cooling at low speeds and at idle.
I did both and my trans temps dropped for 190-200 down to 140-150.

 

Do what I did and install a 26-row 6.0 trans cooler....your trans will never overheat then. Mine worked well throughout the dry/humid Texas summer and kept my trans cooler than it's ever been.

 

I was thinking something along these lines, they have a thermostat switch that turns the fan on at 180 and off at 170. I thought that would work well. What do you guys think?

Derale Cooling Products 12742 - Derale Performance Dyno-Cool Remote Fluid Coolers - Overview - SummitRacing.com

 

I like the idea of a cooling fan, but personally, I wouldnt want the hassle of wiring up a fan when there is a big one right in front of the engine thats already moving..., but thats just me.
Bigger is better especially if your working the truck like plowing, Take into consideration the GVW and BTU rating of the cooler that you like. A stacked plate cooler is also more efficient than a fin and tube cooler.

 

Definately look into the 6.0 cooler mod and if you do it replace the tranny bypass valve. I think its like $30 to $50 from ford.

 

Where would be a good place to get a 6.0 cooler and what is the bypass valve all about?

 

Search ebay or some of the site vendors sell a kit with all the needed fittings and the cooler. Here is a link to the bypass valve. I put the 31 row cooler and a new bypass valve, hottest she got was 160 during the summer heat. I learned about the bypass valve after I did the cooler. When i did the cooler it was still running a little warm then I did some more searching on another site and learned that the check valve will go bad in the bypass valve and cause tranny to run hot., so i put a new one on and she is back to normal. Good luck. hopefully link works.

1999-2003 Ford 4R100 Transmission Cooler Bypass Valve

 

How much air does the fan pull at idle to low speeds? If I put a 6.0 cooler in will the fan pull enough air through at idle and low speeds to keep my temps down? Will the 6.0 cooler then keep my temps too low during highway speeds, were I am okay right now? What is the ideal temp for a auto tranny to be at?

 

According to Diesel Site where I bought my Tru-Cool, you don't need the themal bypass for the 2000 7.3 . It states the transmission already has one. I'm installing my new HD 4R100 today and i wasn't planning on installing the one that came with the cooler. Now I have my doubts that i shoud.

 

Yes, the tranny bypass valve already comes with the tranny from the factory. I think it helps in cold climates to help warm the fluid quicker. I replaced mine when i put my 6.0 cooler on because supposedly it is one of those things could just go bad. If im not mistaken guys in warmer climates delete the bypass all together. Maybe someone with more tranny expertise will chime in. Good luck. Where did u get you new tranny?

 

So I understand you. Your saying that if The original transmission is replaced then a new bypass must be installed. Was the bypass in the old transmission inside the transmission and nothing that can be seen without tearing into the tranny. I've poked around under the truck and don't see anything that resembles a bypass. If the new HD4R100 doesn't have one I should probably install the one that came with the Tru-Cool. What you think?