Question for the group....I have 1991 XLT Lariat with the tow package. It is the 302 with the E40D trans, pre-wired trailer electrical, and the heavy duty radiator. Did this come with a trans cooler? I took a quick look underneath and did not see any lines running form the trans to the radiator. I am towing a 7K pound travel travel trailer RV with WD hitch. The truck pulls it great and even fairly "strong" uphill. I am pretty sure the trans fluid is getting WAY too hot though and want to put an auxiliary trans cooler in but can't see where to hook it up. Any help is appreciated.

 

All slushboxes have coolers, especially E4ODs. The lines run along the R frame rail, under the starter & engine mount. The cooler is between the grille & condenser, and there's another inside the radiator tank. Read this caption:



Also, check the trans for a sticker or tag indicating it has been rebuilt. If it has, no problems. If not, start shopping for a rebuilder now so that WHEN (not "if") it goes out, you'll know where to take it. It's expensive, but after a rebuild, the E4OD is among the strongest & most-reliable slushboxes ever offered in a 1/2-ton truck.

 

The transmission lines come into the radiator on the drivers side of the radiator, not at the bottom. Make sure when installing an axillary cooler to either use one with a thermostat or run the fluid first thru the cooler and then thru the radiator. You can cool the fluid far too much in the winter and the transmission will have issues with torque converter lockup. You also need to know that if you install the cooler against the A/C condenser that you'll push heat into the A/C and it won't cool near as good as it did. Allow space in front of the unit if installing in front of the radiator.

 

The condenser (with A/C on) will always be hotter than the trans cooler, so no heat will flow from ATF -> refrigerant. And it would take about a foot of separation to keep most of the ATF air from flowing thru the condenser.

 

Steve83, the hottest design limit on any automotive condenser I show in the books is 80C. That's 176F. Transmission temps, as I know you are aware, can exceed 265F while towing otherwise transmission temps generally mirror coolant temps. A/C ain't my thang but in 2004, Ford put a remote transmission cooler on all trucks and it's about 12" in front of the radiator. Considering I have a 91 in the barn, he doesn't have the 12" in front of the radiator so placement is going to be critical....if you want the A/C to work right.

My 91 has an auxillary unit on it rated at 6000 lbs. I first put it in front and on the A/C condenser and the A/C went downhill quick. I moved it behind the radiator and it was okay except when towing max loads. Then the coolant was shoving heat into the ATF with both climbing past acceptable levels. It now resides behind the front bumper. It apparently doesn't have to be in direct air flow from the fan as it works really good there. But I do caution that the flow of ATF must be from the transmission to the cooler, to the radiator. Otherwise, you'll be running the transmission too cold and torque converter lockup may never happen.

 

No, I've never gotten into slushboxes, so I didn't think they ran that hot, especially on 1/2-tons. I've never been burned by an ATF cooler, but condensers & discharge lines...

Even so: I still don't think his ATF cooler will have a noticeable effect on his A/C unless both the trans is messed up (generating too much heat) and the A/C is messed up (already working at capacity).

But I've been wrong before...

 

Guys, thanks for all the advice. The cooler arrived today and I'll be installing it tonight or this weekend. I'll plan on placing the unit behind the bumper in and area with decent airflow. I'll also plan on running trans line to cooler then to radiator as suggested to avoid winter converter lock-up. I don't use the truck much in winter, but just in case. Before next towing season, I'll also switch to synthetic fluid and have the filter changed (this fluid and filter has less than 20K on it). That should get me through without destroying my trans too quickly. The trans has under 90K on it and is still going strong, so hopefully no problems. But this is the first time it is pulling this weight too.

Thinking about cat-back high flow 3" exhaust to help get a bit more horsepower out of the 302 too. Thoughts?

 

@Labnerd, can you take a picture of your behind the bumper placement. I think that is what I want to do, but did not see a good place to mount on quick review last night.