1999 F-150, Supercab, 4.6, automatic. Mobil 1 synthetic in engine and Valvoline synthetic (Mercon V) in the transmission.

I had just recently purchased a 4000 lb travel trailer. Toung weight is 280 lbs.

I can tow it ok with my truck. Actually no problems at all except it complains a bit going up hills. I was told not to tow in overdrive. As a result the engine screams at around 2800 rpm when doing 65 mph and my mpg is around 9.

I just recently discovered that I can tow in overdrive with little problems. It will downshift from time to time when going up a slight incline. When going up a hill I will take it out of overdrive.

My question is........am I killing my transmission? The engine temp does not go up at all. Can I continue to tow in overdrive if the transmission doesn't hunt for gears? Please advise, going to Arizona soon.

 

I think you'll do just fine... the only time to worry about towing in OD is if the transmissions 'hunts' a lot... jumping excessively between 4th and 3rd. If it is only happening once in a while, then use the OD.

PS: Tongue weight seems rather light for a 4000 lb. trailer. On average, tongue weight should be in the 10 to 15 percent range for a trailer of this size to prevent sway. You sure it weighs 4000 lbs?

PPS: 2800 RPM aint 'screamin'. My 85 with a 4.10 turned better than 3K at 65... now that's turning.

 

Thanks for your reply. The trailer is a 26' ultra-lite by Rockwood. The weights I posted came out of the manufactures booklet The water holding tank in in the front of the trailer and that holds 25 gallons. When I fill the tank it will add about 200 lbs to the tongue.

The trailer tows great. I get a slight sway when I pass a truck or get passed by one (which seems to be the norm when I tow), other than that it's fine.

When I'm going 65 in overdrive, it turning around 1700 rpm. When you're used to 1700 rpm, 2800 is screaming.

 

I hope that you put on a tranny cooler ??
if you did not you could be sorry
DONT ever let the dealer find out you tow in OD !!!

 

Intresting that the 01 sales brochure for F150 says you need the tow package to tow more then 4000lb. Includes a tranny cooler. But, when I bought mine in 99 the sales brochure said nothing about limits or when the tow pkg was required. But if you look at the 99 towing guid for all Fords, the tow pkg is required on F150 over 4000lb. Seems like real good advice.

 

Overdrive is just a different combonation of the clutch plates and sun/planet gear sets. If your driveing at high speeds i would suggest using overdirve, it keeps the rpms lower. Just before you start to go up hill turn off the overdrive to give you the extra torqe to get up the hill a little better. Basically, if your towing with an automatic drive it like a stick shift. Dont let the tranny chose to shift, you shift it as you go.

 

I just recently towed a 5500 lbs trailer from Buffalo, NY to Bozeman, Mt behind my 2000 expo with the 5.4L, towing package, LLS, 4R100 tranny, and stuff in sig. I could not hold 70mph in overdrive so i took it off about 30 miles outside buffalo and i averaged 10.5 mpg out of overdrive on the way out. then when i dumped the trailer in Montana and my truck would not stay in overdrive at 85 mph. so the bottom line is there really is no difference if you have it in or out of overdrive on long trips, the computer will tune itself for whatever rpm you are running. Keep it out of overdrive if it cannot keep it in.

 

ScottyBones
That didn't make a lot of sense, were you saying the truck wouldn't stay in 4th at 85 mph even without the trailer?

 

Hey indy,

You got it, it would not hold overdrive because i had just drivin 2200 miles out of overdrive. The computer had tuned itself to run out of overdrive at highway speeds. i let it sit for a few days after and then did some city driving and it was back to normal. it just shows you that the trucks will tune themselves to run optimal MPG whatever the load or the gear.

 

I towed my new boat back home today, about 120 miles. The boat on the trailer weighs just over 7000 LBS. I drove with OD on and mine did very well!! Never a hunt one. I would lock in OD going up a hill until it dropped RPM's then it would downshift until speed was back up then conservitivly would drop back into OD. Never had to manually take it out and I hit quite a few hills and inclines (from Lake Texoma to Dallas).

It did great!!! I'm seeing that I did right with all the mods I've done. It was fate. I was moding for towing a boat and didn't even know it!! Got great MPG too for what I was towing and the conditions. See my post in Expeditions under "My Expy Towed Like a Big Dog".

 

I'd just like to repeat what some have been saying... If you tow in overdrive, make sure that you have a tranny cooler. If you tow often, it might not even be a bad idea to install a tranny temp. gauge.

The reason for this is when the tranny shifts out of overdrive and into third, it heats up the tranny fluid. As this heats up, it's lubracating properties begin to break down, and thus, the tranny continues to heat up, causing excessive wear and tear on the gears.

If they had only built today's trannys with the materials of yesterday... these things absolutely would be bulletproof.