rxfoot

OK...I'm a newbie to this forum and I thought my truck info would automatically show. Mine is a 2008 F150 Lariat Crew Cab, 5.5 bed, 5.4L, with, I think, a 3.55 or 3.73. Also came with the factory towing package. and THANK YOU for all the comments.

smokeywren

No, there is no automatic signature with your truck info. If you want it to show, then you must edit your signature to add the relevant info. To do that, scroll up to the top of this page and click on "user CP", then scroll down to "edit signature" and click in that. After you write your sig, be sure to save it.

Then your new sig will be included with all your posts - even the post above that doesn't show a sig yet - unless you specifically tell the post editor to omit your sig for a new post.

A sig takes up space and bandwidth, so I try to remember to include my sig for my first post in a thread, but then omit it for subsequent posts in that thread - or at least on that page of the tread. I'll make an exception and include my sig on this post, so you'll see what a simple sig could look like.


I don't have specs on the 2008 F-150, but I suspect it's the same rule as applies to the '11-up. The factory tow pkg, both the regular and the max, came with both an OTW and an OTA tranny cooler. It's not practical to enlarge the OTW cooler in the radiator, so your best bet is to replace the stock OTA heat exchanger in front of the radiator with a larger heat exchanger - or replace it with a much-larger tranny cooler under the truck.


The Ford tranny engineers discourage folks from adding a third heat exchanger to the tranny cooling system because very few would do it right. "Right" includes not reducing the flow of ATF through the cooling system. If you do add a third heat exchanger, or replace the OTA heat exchanger with a bigger unit mounted under the truck, then when you think you're done, the last step is to do an ATF flow test.


To do that, disconnect the return line from the tranny just before it goes back into the tranny. Then point the disconnected return line to a clean container and start the engine. As soon as you have full flow of ATF out that disconnected line, move the line to another clean container for exactly 15 seconds, then move it back and kill the engine. On a Ford 4R100 tranny, you should have at least one quart of ATF in your container (or one gallon per minute (GPM)) flow. (I suspect the same 1 GPM rule applies to any Ford auto tranny, but check a shop manual to be certain.) If you don't have at least one quart in 15 seconds, you have added too much restriction to the tranny cooling system. Maybe a kinked line, crimped connection, or maybe your new heat exchanger simply has too much restriction built in. In any case, do not drive the truck until you have restored the full flow of ATF through the coolers.

tony montana

Just got back from camping today. I watched my Trans temp closely. Highest I seen was 203 and that was only for a minute or so. But we only went 50 miles away from home. Mainly stayed in the lower to mid 190's. My tt weighs 5100 dry and I would say with me wife and kids and cargo about 6100.

rxfoot

Follow up: spent about an hour with the service manager and transmission specialist at my dealership yesterday discussing my problem. They found a blocked by-pass valve. May or may not be the total problem but, coming home, the temp stayed at 161 degrees. Going to the dealership it went up to 229. Thanks again for all your replies.

smokeywren

Yep, that will do it. That usually means the hot ATF comes out of the torque converter, hits the bypass valve and bypasses the tranny coolers and instead goes right back into the tranny without cooling down any.

rhicks20

I have some questions about the tranny temps also.
My 2014 and the 2013 I traded for it run around 190+ on the highway and get there pretty quick.

I rode in my fathers 2014 with a 5.0 this weekend and his temps never went over 160 on the same route I was on. When he pulled in, he was at 150 and I was at 195.

Both of our maintenance intervals on our trucks show 140000 miles for fluid and filter change. If mine runs 40+ degrees hotter, how are our intervals the same. It would seem that mine would need to be changed sooner than his.

The trucks are the same except motor and mine is 4x4.

tony montana

My tranny runs about the exact temperature. About 190. I wouldn't worry about it

smokeywren

Modern ATF will live without deterioration at higher temps than the older formulas of ATF. Way back when "type F" was the Ford ATF of choice, about 175° was the max sump temp before deterioration began. But today that max sump temp is over 210° for the MERCON LV ATF that is factory fill in your tranny. The sump temp red line is still 225°, so realize that your tranny is probably going south in a hurry if you see over 225° tranny temp.

desert_rat

I am pretty sure the redline is not 225 degrees. I had my trans temp up to 230 once and it was while pulling a 26' travel trailer up a steep grade from a stop. The gauge barely read over the halfway mark. The redline must be much higher than 225.

Platinum T.C.

My 2012 Fx-4, 3.5 Eco, 3:73 ran around 1992 to 195 Deg.
Whet up to 205 one time 4-wheeling up to 13,000 from 10,000ft.
It was a steep & hard climb.

Haven't had my 2014 3.5 Eco. 3:55 Lariat off Road yet.
It stays around 192 to 195deg.
Next Summer when the Snow melts in the High Country.