Using O/D while towing or not

[MaverikDS]

Hi All,
I know there are different beliefs for this so I'm hoping to get some feedback for my specific scenario. I have a 2001 that I'm going to tow a 1970 Mercury Cougar Convertible with. I'm going roughly 175 miles (+/-5 miles) on what I would consider pretty flat land. Probably going to leave early in the morning when temps will get to maybe a high of 70 by the end of the drive.

I do not know if my expo has a tow package or any of the accessories that it came with. I'm using a u-haul trailer and connecting with a regular 4 pin connector. I'm driving in CA so the max speed I can go is 55MPH. I don't anticipate that the car will want to shift from O/D to 3rd frequently hunting for gears, if it did I will definitely turn off O/D, but am unsure if I should drive with O/D off anyway.

The arguments I have read are that leaving O/D engaged and allowing it to be used will cause more heat. The resulting higher heat will be more harmful and a higher likely to risk the transmission. The other side of people believe that provided the transmission is not hunting, allow the transmission to use O/D. This will allow the engine to work less and result in better mileage.

I checked the owners manual and it did not say in the towing section to disable O/D while towing unless you needed the engine braking or preparing to accelerate in hills basically. Although I always try to get the best mileage, I do not mind driving with O/D off if it in some way would be better for the overall health/longevity of the expo.

For anyone truly interested:
Driving between Chico CA and Oakland CA. I don't plan on speeding I will just get behind a semi and use cruise control at 55 probably. Thanks for your thoughts.

 

[Mediamonkey11]

It all depends on if the truck starts hunting, I think that weight and speed will put you in the grey area where you'll have to just see for yourself... I'm not a fan of using CC while towing though, it doesn't give the truck room for speed error to reduce strain when going up slight inclines, I'd rather drop 5 mph than rap the engine personally lol! Just use your best judgement, my bet is it will likely be fine with O/D on if you don't use CC, if you do it'll likely start to hunt on the slightest incline.

 

[toms89]

I have always used overdrive while towing as per the manual. Only if it would start to hunt or going down steep declines do I turn it off.

Not sure how overdrive would create extra heat unless the converter was unlocked and slipping. But our torque converters are generally locked except in first gear when accelerating from stop.

 

[AskMeLater]

We used to be taught that you should not use the overdrive if you're towing loads that were on the "heavy" side. The reason being that the o/d gear is weaker and can burn out easier when subjected to the extra stresses associated with pulling a "heavy" load. I would guess that that's the heat you're hearing about. It's not that using the o/d causes more heat. It's the extra load which is causing the heat, and that extra heat/stress is bad for the o/d gear.

At least, that's what I remember learning when I went to school back in the early 90s. Maybe things have changed since then. Maybe some of you other old timers can help me out or correct me if I'm wrong.

 

[toms89]

One thing I did not consider is while in drive (3rd with 4 speed) there is no gear reduction or overdrive. The input shaft is locked to the output shaft for a 1 to 1 ratio. In overdrive the output shaft is spinning faster than the input shaft thus it can potentially create more heat depending on the load as said.

But still think you would be ok towing on level ground. If you feel the engine being loaded up and/or it starts hunting I would then consider turning overdrive off.

I personally do not like the increase in rpms on the motor unless it becomes necessary.

 

[MaverikDS]

One thing I did not consider is while in drive (3rd with 4 speed) there is no gear reduction or overdrive. The input shaft is locked to the output shaft for a 1 to 1 ratio. In overdrive the output shaft is spinning faster than the input shaft thus it can potentially create more heat depending on the load as said.

But still think you would be ok towing on level ground. If you feel the engine being loaded up and/or it starts hunting I would then consider turning overdrive off.

I personally do not like the increase in rpms on the motor unless it becomes necessary.

That is what I was seeing in other posts about the heat. I ended up towing using O/D for the most part. I would lock it out if I knew I was coming up on a hill or something else but for the most part it was fine. I did notice that the car liked 57/58MPH more for going into O/D vs 55 and I didn't think I would get a ticket just a little over so that's what I did for a majority of the trip. Was sure nice driving back home once I got the trailer off though. I was also really surprised by the MPG I was able to get while towing. Although I didn't refill at all on this trip (360ish miles roundtrip) I thought towing the extra car would dramatically drop down the efficiency. I suppose doing just under 60 towing a car isn't that hard on the expy once you are up to speed.

 

[GJarrett]

Well, the trip is already history so this post is for the record... but here's one other thing I was thinking while reading your original post. You're asking for towing advice pertaining to a 175 mile tow and worried if using O/D could hurt your transimssion.

Lessee here and think this one out... you can simply not use it and get maybe 5~6mpg less than if you played around in and out of it to keep the Expy from hunting gears and overheating. So another way to ask your question is, "is it worth the risk to fry my transmission so I can save 5 gallons of fuel?"

On the other hand, I don't know what Expy you have, but I know mine would haul that tow no problem no matter what, so no-harm-no-foul.

 

[bedrck46]

On the other hand, I don't know what Expy you have, but I know mine would haul that tow no problem no matter what, so no-harm-no-foul.

Just to nit pick a little

If you looked at the OP's profile you would see he has a 2001 xlt with 5.4

But when I looked at your profile it shows you don't have an expy as a matter of fact it doesn't show any vehicle


Have to chalk this up as the laugh of the day

 

[GJarrett]

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