I have a 2000 2wd with the 5.4 in it. I tow a travel trailer and loaded is 6500lbs. Today leaving the campground I had to climb an extremely steep hill as soon as you left the campground. No time to build speed. The old Ex made it, but I was definitely worried. The truck ran fine the rest of the 2 hours home. I went to back my camper into its spot to store, and smoke started coming out from under the hood. When I crawled under it, tranny fluid was leaking on the ground. A pretty steady drip. I let it cool down, added fluid and drove around. Didn't leak anymore. Did the tranny just get hot and had to burp??? The drip was coming from where the tranny connects to the motor.

 

The seals between the Torque converter need to be replaced. A newer Viton Seal is available.

@AlaskanEx went through this and should be able to assist.

 

Yep, as Coop said it sounds like your trans did a little overheating and puke out the TC seal, a fairly common event on 4R100s that have been working hard then shifted into reverse and backed (uphill usually) up, most times there is a trailer involved.
There is a new seal (made from Viton) that is much better able to deal with that excessive heat than the original seal. The seal is pretty cheap but the trans has to come out to do the simple installation. As long as the sealing surface on the TC snout is not scored (by any debris exiting there during the puking event) the new Viton seal should be your fix. Being a RWD EX the cost of doing the job should be a little less than a 4X4 model. Unfortunately another way to help limit the heat buildup while reversing is to shift to LOW range, which as a RWD rig is not an option for you. For now if you are not seeing any more leakage with typical daily use you could possibly control the likelihood of another event by letting it cool off in park at idle for 10-15 minutes before doing the backing up that lead to the event.

 

If it has overheated, you'll want to swap all the fluids out. The lifespan of ATF gets reduced drastically the hotter it gets over normal operating range (with a safe max of 225°) and the additives and similar burn off or break down. Starting around 230, varnish can start to form. Seals and such tend to harden around 240-250, and everything above that just causes mass carnage. It may not manifest itself immediately, but the damage has been done. Around the 230-240° range, lifespan has been cut in half for the fluid as well.

I'd also recommend upgrading the transmission cooler for future peace of mind.

 

I did go through this when I bought my camper and brought it home. The fluid itself isn't overheated it's the seal just doesn't want to seal when it gets warm. I had a local transmission shop put in a new seal and some other stuff for $660 same day with new fluid included. Bothered me when I had it happen but it's very common. I had my issue like 3 years ago and since having the work done she's dry as a bone underneath.

 

That was true for 1960s ATF. It is NOT true for modern ATF. This is just scare tactics, there isn't a shred of truth to this.

That's not a bad thing, but it is of limited help in this situation.

The extreme slope you had to climb worked the torque converter very hard. This got it hot, the seal softened. and it leaked. Once it cools down it usually will seal again. If it isn't leaking it's fine.

If it's a 4x4 you can eliminate this problem by using 4L to climb that steep slope.

 

Thanks for dispelling the myths Mark, I appreciate it. OP, I apologize for providing crappy info!

Mark, if the temperatures don't really apply anymore then why do we bother watching them? Not arguing at all, I'm just curious now. Is it to keep other items and components happy such as seals, clutches, etc? At what temperature exposure should one swap ATF?

 

Temperatures DO apply, but the doom and gloom that was in your post is not accurate.

You can run up to 220F all day long with no problem. You can go up to 250F for up to a half hour at a time with no problem.

If you get the internal trans temp over 300F, change the fluid.

 

Gotcha, thanks for clearing things up!