Towing in Overdrive

Bilcin · 08-06-2011, 04:57 PM

I searched the forum and didn't see an answer to this question. If there is a thread with the answer I apologize. I took a round trip of 1000 and used the OD lockout option. I was amazed at my poor MPGs of 8.6 MPG. At 65 MPH I am doing about 2850 RPMs. On a flat section of highway I put the truck in OD and the RPMs dropped and during the 12 miles stretch it went from OD to 3rd gear only once. I was traveling at 65 MPH and towing a Wildwood 26TBSS with my 2005 Ford F150 5.4 liter V8 3.73 gears. How many times is switching gears from OD to 3rd gear too much? I kept an eye on the engine temp gauge and it remained in the same position as when I am not towing.

Bilcin

jackhartjr · 08-06-2011, 05:03 PM

I guess my question is this, why block out the overdrive? Use it, that's what it's there for!
Jack

JoeR · 08-06-2011, 05:13 PM

Does the Ford have a towing package with a larger tranny cooler? If not, I'd consider putting one one for OD towing, as well as, a tranny temp guage.

My 1/2 ton truck has the towing package and it came with the larger cooler and temp guage. I don't mind towing across country in OD. And 8.5mpg is better than 7.5mpg.

Most trucks I've seen get between 7 and 12mpg towing larger rigs.

JR

Bilcin · 08-06-2011, 05:25 PM

Yes, my truck has the tow package, trans radiator sits in front of the bigger engine radiator. The reason I am asking is if the transmission isn't "searching" for 3rd gear or OD is it ok to use OD or towing in OD heating up the trans to the point of damage being done?

daverain · 08-06-2011, 06:52 PM

Bilcin,
It's my understanding from Ford that the trans will not be damaged with some od to 3rd. shifts. The trans in your truck is most likely either a 4r100 or 4r 70 or 75, either case it's computer controlled and will stay out of lockup (od) if the converter gets too hot. My excursion, equipped with a trans temp gauge will lock out of od if the temp gets too hot, but that's only in the mountains, on I95 its in od almost all the time. Just my 2 sense.
Dave and Rainy

Bilcin · 08-06-2011, 07:42 PM

Quote:

Originally Posted by daverain

Bilcin,
It's my understanding from Ford that the trans will not be damaged with some od to 3rd. shifts. The trans in your truck is most likely either a 4r100 or 4r 70 or 75, either case it's computer controlled and will stay out of lockup (od) if the converter gets too hot. My excursion, equipped with a trans temp gauge will lock out of od if the temp gets too hot, but that's only in the mountains, on I95 its in od almost all the time. Just my 2 sense.
Dave and Rainy

Dave,

Thanks, I was kind of thinking the same thing. I read that excessive gear shifting between OD and 3rd gear would overheat and damage the trans. So it makes sence that limited shifting will not do any harm. What are your thoughts about lower RPMs with the same torque on the trans? Does this affect the trans temp?

jimh · 08-06-2011, 07:43 PM

you probably have something in ur owners manual abt it. on my diesel, the recommendation is to leave it in overdrive; the computer will make the choice.
i have taken it out of overdrive on steep grades to help with the braking.

acadianbob · 08-06-2011, 07:49 PM

I have exactly the same truck and tow in overdrive whenever possible. When not hilly or a headwind.

Hybrid21SS · 08-06-2011, 07:56 PM

I added a TransGo shift kit to my Avalanche. The 3-4 shift is sloppy and the kit firms/quickens it up as well as other shifts. Also did the larger Corvette servos. I leave it in overdrive..

Goomph · 08-06-2011, 08:20 PM

Overdrive .... Unless it starts hunting for a gear. When I see a steep hill, before it has a chance to start hunting, I kick it out of overdrive.

I also have a ScanGaugeII which shows my transmission fluid temperature. if I see the temperature rising, I start to go slower and not push the truck to keep my regular speed *55-60 mph), I disengage the overdrive until whatever is causing the TF temperature to rise disappears.

JoeR · 08-06-2011, 09:07 PM

ScanGuage II, everything an information junkie needs and more. I love my ScanGuage. I set my guages to rpm, load, temp, and instant mpg while towing.

JR

Bilcin · 08-06-2011, 09:28 PM

Thanks to all who replied, next Sunday I will be going from Philadelphia to Danville Pa (Knoebles amusement park) and will be traveling on the PA turnpike and route 80. I will let you all know if I have a transmission meltdown!

jimh · 08-07-2011, 06:25 AM

i've been told the heat is built when the transmission keeps going in and out of overdrive.
the factory transmission temp gauge on my truck has always been happy so i doubt that i see changes of a few degrees. those that have more precise instruments can be more of a help as to when it may occur.
i do the same goomph and take it out of overdrive when in hills or at a magic speed that minor changes causes it to go in and out of overdrive.

Zhanna · 08-07-2011, 06:46 AM

I know this is not the same thing but . . .
my Ford Escape owner's manual said to turn the overdrive off when pulling a trailer. So when I was pulling my little sheep wagon, full of sheepies, I would take the overdrive off.

daverain · 08-07-2011, 08:56 AM

Bill,
To answer your question about rpm's. My mileage does go down 1 mpg in 3rd. vs leaveing it alone in o.d. If Your going to up to knoebels you will want to lock it out of od, those hills really beat up the truck. Have fun.
Dave and Rainy

Great Lakes · 08-07-2011, 10:22 AM

How hot is too hot?? What is the maximum allowable transmission oil temperature?

Tom T.

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2011 Rockwood 2104 Mini Lite

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acadianbob · 08-07-2011, 10:35 AM

You need to know what your normal temp is. They are all different. I'm less than 10 degrees warmer than normal when towing.

Great Lakes · 08-07-2011, 10:59 AM

Quote:

Originally Posted by acadianbob

You need to know what your normal temp is. They are all different. I'm less than 10 degrees warmer than normal when towing.

Thanks Acadianbob. I'd been looking in my 2011 Chevy owners manual for some discreet number, but wasn't able to find one. Guess I'll just see what the "normal" temperature is during an unloaded run down the freeway and take it from there.

Tom T.

EDIT: Finally found the normal operating temperature for my truck, which is from 160 to 200 degrees F.

____________________________________

2011 Rockwood 2104 Mini Lite

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Bilcin · 08-07-2011, 11:32 AM

Quote:

Originally Posted by daverain

Bill,
To answer your question about rpm's. My mileage does go down 1 mpg in 3rd. vs leaveing it alone in o.d. If Your going to up to knoebels you will want to lock it out of od, those hills really beat up the truck. Have fun.
Dave and Rainy

Dave,
You are right, there are some nice hills up there. Will not be in OD.

Bill_C · 08-07-2011, 02:32 PM

When the transmission is in OD, with no shifting going on, (tranny discs slip when changing gears which creates the heat) there is no heat generated in the convertor or tranny itself. It is when the engine is getting overloaded and begins to heat, it will transfer its heat to the tranny cooler, heating the tranny oil rather than cooling it.

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