This may have been discussed in the recent past but I'm throwing it out again. I have a small boat(2000lb or little less). I have the 5.4 3v with 3.55 rear end in an 05' Screw. After towing it around to a couple different lakes this weekend, I observed the following: 1) While towing this boat with the OD on, the RPMs on the motor were around 1800 at 60mph roughly, which sounded good and I didn't notice the tranny doing any excessive shifting 2) Towing at 60mph with the OD off bumped my RPMs up to around 2300-2500, which made my engine run a lot harder, however the tranny seemed more responsive. My question is this: Even though the towed weight is fairly light, is it better to tow with the OD on and possibly put my tranny at risk or tow with the OD off and put my engine at risk? What's the safer option(besides not towing anything at all, LOL)?

 

And make sure you have a good transmission cooler. I personally use a bottle of Lucas trans additive in every vehicle I own. Dont bother with any other brand, spend the $10. on the Lucas.
With the engine reving at the rpm you mention, the load is actually quite low on both engine and trans. Now that I'm thinking of it, I also use a half bottle of Lucas engine oil treatment in my motor. Only half because these engines like thin oil, I wouldnt want to thicken it up much.
If your going over 60, then I'd use the OD, your rpms would be slightly higher (in OD) to push the extra load easier.
Another thing that might concern you on a long trip would be economy being out of OD will suck down fuel like a pig, reving at 23-2500

If you chose to add it (trans); Drain a qt. out of your trans before adding it. Make sure it's warm (the bottle) or it wont even come out. It's like molasses, I normally fill a sink with VERY hot water and let it sit in there for like an hour. Then wrap a small towel around the warmed bottle to help keep it warm while pouring it in.

 

I'm not sure what the limit is on that. I have burned a tranny up in a PS diesel F350 towing in OD on the highway and that was a Heavy Duty trans. The truck seemed to handle it fine (7.5L go figure ( : ). I was informed that is what screwed it up and not to tow in OD.

BTW - I was trailering another vehicle (1100 mile trip). More weight , but more truck as well.

 

As said in a jillion other threads here, the goal when towing is to keep the converter locked as much as possible. Whether it's in 3rd or OD doesn't matter.

 

I learned to drive when I was 8 years old. It was an old International 3 ton with a 6 banger gas engine. When hauling any load, either in the truck or pulling, if you are having to use half throttle and losing speed- you're in the wrong gear. It's worked for me over the years. If you are having to use half of the gas feed, drop a gear. It's easier on the engine and tranny but more importantly, you.
I also have a 4.6 with cams for pulling that has 3.73 gears. I probably should have gone with a larger truck but I already owned it. It does a fine job at pulling trailers for what it is but I generally will shift the tranny with OD lock out a lot. When going up any incline I lock it out. When going downhill or on level ground, I will have it in OD but I don't crowd the engine for power. I use the gears to pull the load moreso than the engine. For your truck and boat, I wouldn't think that you would need to drop any gears unless you have some fairly steep inclines in your part of the world. It may be a good investment for you to put a transmission fluid temp gauge on your truck. It will tell you when the tranny is getting hot and if you should be running a lower gear.

 

Thanks for the info guys,
I live in Georgia where it's pretty flat. I haven't noticed it shifting out of OD so long as I'm running 55 or faster with the boat hooked up. I was a little concerned on the interstate b/c I didn't feel good about running 60-65mph with the OD off b/c the RPMs seem so high. Guess I'll run it with the OD on so long as it doesn't unlock my TC any more than normal. Didn't know if the OD gear was designed to use as a pulling gear.

 

It's not. OD isn't designed to pull any weight. A little won't hurt it. It's not to the slipping in and out that hurts it - It's cruising speed in OD that heats it up. If your not set up w/tow package and If the fluid is marginal you can screw up that OD band pretty damn easy.

When that one went on me - it never went in and out gear. The fluid wasn't burnt - It just got to hot @ cruising speeds. You might be alright on a very short trip, but I wouldn't chance it , trannies aren't cheap and why chance it?

 

My truck has the tow and go package but Jbrew, what you say makes perfect sense. I can't see how the OD gear is s/u for pulling much of a load. My buddy who lives on a farm and pulls regularly heavy and light loads ALWAYS tows with the OD off. He's got right at 150k miles of hard towing on this tranny and it's still running along. Might take your advice and his for this. I don't mind letting the engine rev but I've wondered about the tranny is towing with the OD on.

 

Seems to me the converter will unlock and/or it will downshift before you overtorque the OD band. It's an unlocked converter that causes the temps to climb.

 

I don't think the TC is unlocking but if it is, I can't feel it. I don't notice the RPMs jumping around. Ford's manual doesn't give a clear description of how to best tow. The manual instead tries to explain towing 101 instead of how to best protect your vehicle's powertrain while towing. The OD on/off button shows a picture of a trailer but doesn't talk of it as a tow/haul button. As far as I can tell the only difference in how the the tranny works is it locks out the OD. On my 03' Z71, the tow/haul button would actually extend out my tranny shift points even to let me enter OD to allow for better towing capabilities. I don't feel any shift differences in that department with the F150. I do notice as I slow down after letting off the throttle with the OD off, the tranny rides the gears down a little more than with the OD on. I can tell this b/c of having the flowmaster mufflers. I can hear it rumble more when slowing down with the OD off.

 

compression braking, just like semis, since the vehicle Physically cant go any faster than the engine can turn (revs), by having a lower gear between the engine and wheel the natural state of a gas motor to want to drop RPMS with no accellerator pedal input the whole thing wants to stop rolling (in essence anyways )

 

Yeah, it sounds just like a semi, but on a smaller scale. I had looked at a Titan not to long ago. This truck has some kind of feature that allows you to manually change gears with the flip of a switch. Sounded good in theory.