1st tow with the T4R: what I learned about OD, mpg, and tranny temps

[Rancho5]

Just got back from a Mesa, AZ to Albuquerque, NM trip towing the camper for the first time with my T4R. I used to pull my Coleman Cheyenne (about 2000 pounds) with my 7.3 Powerstroke like it weighed nothing so this was going to be a bit different.

Here’s what I learned.

The T4R towed awesome! Yes it’s lighter than the f250 so I felt bumps but it was fantastic.

Drove 7/8ths of the way to NM with OD off, as many suggested. I got 15 mpg on average going 75 mph on the flat parts (rpms about 3500) according to the instant mpg display on the EngineLink App. Tranny temps ranged from 155-175 on the flats.

On the really steep pulls the tranny temps rose...obviously...once up to 208. I was prepared to pull over if it ever hit 220 but it never did. I just went slow and on the really long pulls (5 miles longest...long for this trip at least) I just put the hazards on and crept up at 45 mph.

Outside of Gallup, where it’s really flat, I clicked the OD button and went back into OD just to experiment. The instant mpg rose to 19-21 and the tranny temps went down a few degrees. The rig never tried to find a lower gear, so I kept it where it was. When the hills approached I clicked the OD button and climbed right up, and the temps didn’t budge.

I also learned that its really tough to get up to the speed limit in OD if you start from a dead stop on even a slight incline. Not many rest stops in NM so I had to pull over to pee on a hill. It was best to click OD off, get up to speed and then click it back on when the road levels out.

Anyway, with the tranny temps not increasing at all on the flats in OD, and maintaining the speed limit, I think I’ll shoot for higher mpg next time, and click OD off when the inclines and hills begin.

The EngineLink App is awesome and so is the Tekonsha P3!

Anyway, thanks for all the great input prior to my 1st tow!

 

[jgue467]

That's what I've always said, use OD on significant hills/mountain passes and at medium speed (say 40-45) when you want to pass a vehicle or otherwise accelerate as quickly as possible with minimal strain on drivetrain.

Next comes ECT lessons!

Kudos to you! :cowboy:

 

[phattyduck]

I got 15 mpg on average going 75 mph on the flat parts (rpms about 3500) according to the instant mpg display on the EngineLink App. Tranny temps ranged from 155-175 on the flats.

I think I’ll shoot for higher mpg next time, and click OD off when the inclines and hills begin.

Slow down to 60-65 and leave OD off is all you need for better MPG. Your short bit of data at 19-21mpg at 75 mph with a trailer isn't real - you were probably on a slight downhill.

If the torque converter stays locked, there is no problem with letting it shift into 4th/OD - that's how I often tow my little 4'x8' utility trailer. If you need more power to maintain speed, just turn off OD as you did.

Up hills, do your best to stay above ~45mph, as that's when the torque converter locks in 3rd with OD off.

-Charlie

 

[Rancho5]

Up hills, do your best to stay above ~45mph, as that's when the torque converter locks in 3rd with OD off.

-Charlie

I noticed that. As soon as I went down to 40, the car downshifted and the temp started to soar. The longest incline was 5 miles and I once got to 208. I was lucky it wasn’t much longer or I would have hit 220 easily.

Any advise for keeping it above 45 mph on long inclines? So it doesn’t downshift.

 

[thecole1098]

I noticed that. As soon as I went down to 40, the car downshifted and the temp started to soar. The longest incline was 5 miles and I once got to 208. I was lucky it wasn’t much longer or I would have hit 220 easily.

Any advise for keeping it above 45 mph on long inclines? So it doesn’t downshift.

Yes, a supercharger. Seriously.

 

[Rancho5]

My mechanic friend wants to supercharge my rig, not even knowing about the towing. What’s a realistic budget?

Never mind. Waaaay out of my budget....

 

[thecole1098]

My mechanic friend wants to supercharge my rig, not even knowing about the towing. What’s a realistic budget?

You should be shooting for around $2-3k. It's certainly not cheap, but it's the best bolt on mod you can do for these. I considered doing it for my 96, but since it is now just a off road rig that mostly sees crawling, I don't see the point in putting that much for something that won't get a lot of benefit with my application. I could spend that money on armor and full float/disk conversion in the rear, etc...

 

[Rancho5]

Yes, a supercharger. Seriously.

Let me rephrase. Any driving tips or techniques to keep it above 45 on hills so it won’t downshift and rapidly increase tranny temp?

 

[Lindenwood]

Great datapoints!

My only caution is I have never seen an after market MPG calculator accurately depict instantaneous MPG based on load--they all dramatically overcompensate for changes in RPM. So, while the 15ish MPG was likely accurate, the quick jump to 19-21, if it was accurate at all, was definitely not solely from the drop in RPM.

 

[fblainen11]

I towed a 20 ft flatbed from South Louisiana to Kentucky and back. There it was empty but on the way home it was probably around 3500-4000 lbs.

I was about to do 60-65 most of the way on anything but inclines. I towed with OD in hills, but once I got up to hwy speed and on flatter land I could stay in 4th without it looking for gears.

Basically as long as it wasn't looking for gears I kept it in 4th.

 

[gamefreakgc]

Yes, a supercharger. Seriously.

Seriously! :zoom:

 

[phattyduck]

Also, don't be freaked out by a few minutes of the tranny temp going up above 200. The factory sensor is on the outlet of the trans (after the torque converter), at the hottest location for trans fluid. In other words, the fluid is at that temp for SECONDS before getting cooled by the cooler and returning to the transmission.

If you keep a decent drain/refill schedule for the trans, a few minutes of high trans temps here or there won't cause any problems - think of how many 4Runners are still on the road driven by people who know none of this information! The idiot light for trans fluid temp on the dash is set in the 280-300*F range...

-Charlie

 

[gamefreakgc]

Also, don't be freaked out by a few minutes of the tranny temp going up above 200. The factory sensor is on the outlet of the trans (after the torque converter), at the hottest location for trans fluid. In other words, the fluid is at that temp for SECONDS before getting cooled by the cooler and returning to the transmission.

If you keep a decent drain/refill schedule for the trans, a few minutes of high trans temps here or there won't cause any problems - think of how many 4Runners are still on the road driven by people who know none of this information! The idiot light for trans fluid temp on the dash is set in the 280-300*F range...

-Charlie

Agree completely. Sustained heat kills, not a momentary spike.

I hit 230* on a long steep hill for my engine coolant temperature and I was on edge waiting to see if I'd blow a head gasket. But it's been great since and was only at that temperature for a couple of minutes at the most. It usually runs at about 180*.

Heat makes transmission fluid lose its lubrication properties so the biggest thing is to change it once it starts to show as brownish and lost the red color. You don't want to overheat burnt fluid, it does not protect the transmission well.