Thanks for showing me the details that made the difference.

 

As I'm in the Hill Country I suppose taking it for a spin ought to tell me plenty once it's loaded up...

 

I have read a few that are at or just above the max and do OK.
I would definitely look into improved transmission cooling, changing the transmission fluid, even getting a temp sensor for the tranny. The 4R70W is the weak link with a Super Crew at max weight, but if your smart about it, it can be done.

 

I have a factory transmission cooler. Is it not up to snuff?

 

if your towing 8,000 lbs in hills and mountians, not really.
Heat is what kills transmissions, so the cooler you can keep the fluid, the better.

 

What is it that makes it marginal? Surface area? As the harder part has been done I could certainly install a larger radiator or do a modification myself.

 

I have a 2002 F150 CREW with the 5.4 motor . I pull a 2800# trailer with a 7000# Bobcat on it from time to time. No problems. I normally don't do this more than 4-5 times a year and only for 50 miles.. Not a lot of hills. My trailer with a 5500# truck setting on it is in the 8000# range you mention. That pulls easy. I am in central Illinois... not a lot of hills, but holds 65- 70 mph on the highway easy. I think you may be a little worried about the weight.. I am not.... your problem will be on the hills. Downshifting and having the 5.4 motor should be adequate.

 

Nice to know. Thanks!

I am concerned in the hills/mountains, and don't care for being a slug from a stop.

 

At higher altitudes the air density reduces causing reduced cylinder filling and lowers torque production.
The general air pressure at sea level is said to be 14 psi. At higher altitudes the barometric pressure is less. This pressure is what fills the cylinders.
Over heating could be the result if the cooling system is not in first class condition.
Nothing you can do about it otherwise.
Engines equipped with Map sensors can account for differences in fuel injection requirements but still does not keep torque levels the same as at near sea level without air to support it.
Under high altitude high engine load conditions, the road speed is slow, the throttle is open wider, engine running leaner all contribute to higher heat levels
Normally there is some Oxygen left in the exhaust gas and the mixture is a little over with excess fuel.
This excess fuel helps limit the valves and cylinder temperatures.
It's a balancing game in all 4 cycle gas engines.
Good luck.

 

IIRR, there is a 2.5% drop in hp for each 1000 foot elevation, gears will certainly help ease the amount of hp/tq needed to move the weight, but, if you are over 8k feet, ford does have a specific software program that will help a little with ensuring the air/fuel mixture stays correct. In reality, increased ignition timing is the next best because detonation at higher altitudes is less promulgated......the only other real fix is to go with forced induction (turbo, blower) since they are really not affected by altitude.

Yeah, use to live in the San Bernardino Mountains.....5,000 foot altitude.....

 

Personally, I would change to 3.73s or even 4.10s. it will tow easier. Ive towed with 355s. and in hills it will downshift quite a bit. (I have a 5.4 2001 with 3.55s) the way the 5.4 runs the 3.55s are too tall. Maybe Im too picky. but I hate it when my truck downshifts to 3rd and it stays there...............unless I feather the gas..

 

I've actually been thinking the 3.73 gears might make a good compromise. I hate to give up on gas mileage, especially since it won't be pulling continuously, but really wonder about 3.55 gears in the hills/mountains.

I live in the Hill Country of Texas and so I figure loading the trailer and seeing what it does will give me the feel for it. However I wanted to get most major expenses paid for prior to buying a trailer and the things needed...

 

One mistake is relying to much on others statements that they pull this and that with their tucks.
It is no real info for you but there opinion and acceptance of what their truck does for them.
For example the statement just made about a truck shifting to 3rd gear is pointless to anyone but that person.
Reason is starting from OD gear and downshifting.
The trans goes from OD to converter 'unlock' then to third gear.
No truck will 'pull' a heavy load in OD and will drop out below 45 mph in any event even if it did stay in OD.
OD is a band circling a drum in the transmission.
It was not meant to put high engine torque on so down shifting is the norm and is detected by the TPS and speed sensor for the PCM decision to down shift.
The motor only has so much torque to produce before down shifting is a must to pull the total weight. This is built into the program.
Lastly, switching the OD off enables the trans to lock up in third to reduce transmission heat produced by fluid shear.
If the OD is not turned off the trans will not lock up and will generate more heat.
These actions can be seen on the Tach for RPM changes..
Also the motor produces max. torque over 3000 rpm.
You cannot pull a loaded trailer much blow 2500 rpm unless it's wide open throttle in a lower gear.
Been there and done it pulling more than 12,000 lbs with a 4.6L/3:55.
If you put a trans temp gauge at the output of the converter it will scare you the first time you see the temps. under high sustained loads.
The temps are the fluid shearing that goes on in an unlocked converter under high loads.


Good luck.

 

Lastly, switching the OD off enables the trans to lock up in third to reduce transmission heat produced by fluid shear.
If the OD is not turned off the trans will not lock up and will generate more heat.
--------
--that's interesting........ I had not thought about it !

 

I knew you were supposed to turn OD off when pulling heavy weight, but didn't know why and had forgotten. Thanks!