I'm new to the RV life and am concerned over the need for a transmission cooler. I will be towing a 26 foot Jayfeather weighing 5050lbs fully loaded, 4500lbs dry. My tow vehicle will be a 2007 Expedition with 5.4 motor. It's tow rated at 6000lbs. without the towing package and 8500lbs. with the package. Mine doesn't have it. I'm not too concerned about the engines ability to pull it, but since I'm close to the 6000lbs should I worry about burning up my transmission and install a cooler? This would have been standard with the tow package. I do live in South Georgia where it gets HOT. Will be traveling with 2 adults and 3 kids under age 10. Would synthetic transmission fluid help also? I've only pulled it about 20 miles from the dealer and the transmission temp did go up just a little, and I had overdrive turned off.

I would add a transmission cooler just for ease of mind. Heat can quickly kill a transmission. Long climbs will run the trans temp up.

Thanks for the quick reply, I edited the post a little. Could you take another look at it?

Yes. I tried pulling a 4700lb loaded , TT on the flat ground in FL with a 4.6 v8, and almost burned one up.It's a cheap and simple upgrade.You can buy one on the net, that is a factory direct replacement. It snaps into the factory bracket that should already be there.You probably want to pick up an extra few feet of hose. They seem to cut it pretty close from the warehouse.

I do NOT think you will get much debate, adding a cooler will be wise. Check your local auto parts store, adding a tranny cooler is normally a pretty easy DIY adventure. Of course, you will get the debate on whether or not it should be run seperate of the exiting cooler, or in conjunction with the existing. :B BEFORE or AFTER :hI go with "in Conjunction". I also prefer adding the new cooler BEFORE the existing one in the radiator. This "Helps" the existing, while still allowing the existing to do its job. Up here in the colder states, we need that warm fluid in winter time.

Transmission cooler | Good Sam Community

Dirtydude
Explorer
May 22, 2015
I run transmission cooler with electric fan installed after the factory cooler. Running down the road in TC lock up it never comes on. a long hard crawl up the mountain it runs a lot. Also installed transmission oil temp guage in the cab so I know what's going on. If you're going to install a transmission cooler get one with a fan on it. If you're towing up a long bumpy dirt road you won't have enough air flowing over your coolers to do as much good. I'd wire in a small LED light (spot for it on the fan) so you know when it's kicking in and out if you don't have a trans oil temp guage.

I got something like this
http://www.etrailer.com/Transmission-Coolers/Derale/D13960.html

I haul lot's of hay and equipment on a gooseneck and bumper pull stock trailer.
majorgator
Explorer
May 19, 2015
Scrap the factory cooler, if you even have one. Quality aftermarket cooler (like a Tru Cool Max) will far outperform the factory cooler. Don't buy a cheap auto parts store cooler. Ditto on getting the biggest cooler possible.

Also, there's often talk in this forum about running your transmission too cool, but don't buy into that. Heat is the #1 enemy to a transmission, but you'll neer hear of anyone breKing down because it was too cool. Change the fluid every 30,000 miles or so.
Rumblejohn
Explorer
May 19, 2015
We have a 2008 F-150 with a 4.6 and the factory tow package. I have checked the external cooler temp many times with an infrared temp gun, and haven't seen temps over 160 yet. TT is a Jayco 26BH that goes 5300lbs ready to go. Admittedly we tow in Florida where it is pretty flat, and 60-62mph is plenty fast enough.
And yes your trans should have come from the factory with MerconV which is synthetic. Service interval for the '08 is 100k, but I change mine every 30k. Oil is cheaper than a new tranny.

John
Terryallan
Explorer II
May 18, 2015
cbshoestring wrote:
I do NOT think you will get much debate, adding a cooler will be wise. Check your local auto parts store, adding a tranny cooler is normally a pretty easy DIY adventure.

Of course, you will get the debate on whether or not it should be run seperate of the exiting cooler, or in conjunction with the existing. :B BEFORE or AFTER :h

I go with "in Conjunction". I also prefer adding the new cooler BEFORE the existing one in the radiator. This "Helps" the existing, while still allowing the existing to do its job. Up here in the colder states, we need that warm fluid in winter time.

Ford puts it AFTER the radiator. Putting it before kind of defeats the purpose, and the fluid will warm back up as it travels thru the radiator, and would be just like not having a aux cooler on it.
wrenchbender
Explorer
May 18, 2015
Get the largest cooler that will fit in the area,forget about running the a/c when hill climbing.
path1
Explorer
May 18, 2015
lbrjet wrote:
path1 wrote:
(edited to reflect OP edit)

Our class C with a 5.4 leaves our driveway at 10,380 pounds. It's a 2003 and we have lots of mountains we go over. My trans gauge hardly moves on our hottest days going up steep grades at freeway speeds. My gauge barley moves going up steep logging roads at real slow speeds. The cooler is stock, so no need to go for a monster size like 6.0's have.

Also when doing the install I would also put in one of these. http://puredieselpower.com/manufacturer/magnefine-2 and NAPA has their own brand also (same thing just painted different).

There's probably more info with spec's that can be found on-line.

Just because the Ford idiot gauge is not moving doesn't mean the tranny isn't getting hot. Mine tranny gauge doesn't budge until 235 degrees. That's why I have a Scangauge. I want to know if if breaks 200, not 235.

How far off is your gauge, if known?
seaeagle2
Explorer
May 18, 2015
The days of the $400 with core C6, 727, TH400 swapout are gone. On my 2010 F150, the lines were run from the radiator to the cooler bracket I just got a oem style cooler and the short line and installed it.
lbrjet
Explorer
May 18, 2015
path1 wrote:
(edited to reflect OP edit)

Our class C with a 5.4 leaves our driveway at 10,380 pounds. It's a 2003 and we have lots of mountains we go over. My trans gauge hardly moves on our hottest days going up steep grades at freeway speeds. My gauge barley moves going up steep logging roads at real slow speeds. The cooler is stock, so no need to go for a monster size like 6.0's have.

Also when doing the install I would also put in one of these. http://puredieselpower.com/manufacturer/magnefine-2 and NAPA has their own brand also (same thing just painted different).

There's probably more info with spec's that can be found on-line.

Just because the Ford idiot gauge is not moving doesn't mean the tranny isn't getting hot. Mine tranny gauge doesn't budge until 235 degrees. That's why I have a Scangauge. I want to know if if breaks 200, not 235.
Ductape
Explorer
May 18, 2015
Check your manual; probably came from the factory with Mercon V syn.

New fluid never hurts. Unless it's an old trans full of sludge- in which case it's too late anyway.
Grandpere
Explorer
May 18, 2015
I would also add a fan to the aux cooler, this will help on slow climbs up mountains to keep air moving through the cooler.