If you’re really tuned into your truck, you can see what’s going on with the transmission by watching the tachometer. There will be a slight but noticeable increase in rpm when the torque converter unlocks and a couple hundred rpm increase with a downshift. There is likely not much of a mpg change using 6th, nor increased engine wear. It takes a certain horsepower (either fewer larger explosions or more smaller explosions) to overcome friction whether the engine is spinning at 1500 or 1800 rpm. I say let it spin freely and use lower gears when towing or working hard.
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- #1,402
I'm sure it depends on the trailer but I can confirm there's maybe 0.5mpg difference between 4th and 5th when towing on stock gearing, and I suspect unless your load is really slight and aerodynamic and the road is flat you're probably not actually staying in 6th gear anyway but most likely sitting in 5th. The only way to save fuel is just to drive a lot slower. If I try to push 75mph I'll barely get 7mpg, but if I do 55mph I can get 9.5-10mpg. For me though it's worth the extra fuel stops on the really long (1000 mile+) trips because losing 20mph adds up quickly.
Edit: Fun calculator at Fuel Economy Calculator | Davis-Moore - https://bigaldavismoorechevrolet.com/fuel-economy which helps approximate the cost of a 1000 mile road trip. In this example it costs $155 to save over 5.5 hours of travel. Assuming you refill 20 gallons each time you stop, the difference between 10mpg and 7.2mpg is only 3 extra gas stops, which at 10-15 minutes still shaves close to 5 hours off the trip. $150 is worth 5 hours of my life.
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lots of good info in this thread....I've had a few years of good experience with a Redarc trailer brake controller....36"DBH Sugar Maple....couldn't lift it with my wee tractor but with the grapple I could roll and push it onto the tiltbed....
Slow Paddler
SILVER Star
First long trip loaded up with all of our stuff from the old Hiker squaredrop; 1369 miles from Northern Ohio to Alabama and back. Now that I have OBD Fusion working showing transmission temperatures, I feel a *lot* better informed.
At some point I want to get it weighed, as I have no idea how much junk I have in the LC. ADGU system with one drawer coming in a couple of weeks, and I'll fabricate my own fridge slide for it. Then I'll have a better handle on the chaos in the back after ten days!
Somewhere around 100 Oliver trailers at the annual rally at Lake Guntersville State Park.
At some point I want to get it weighed, as I have no idea how much junk I have in the LC. ADGU system with one drawer coming in a couple of weeks, and I'll fabricate my own fridge slide for it. Then I'll have a better handle on the chaos in the back after ten days!
Somewhere around 100 Oliver trailers at the annual rally at Lake Guntersville State Park.
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- #1,406
Went up to Wisconsin this weekend. Ignore the MPG, I was light in the throttle, I was really getting 6.7-7.5 most of the trip.
Transmission temps have been hotter than I’d like since I regeared to 4.88s. They’re about 15F hotter than before. Engine oil temp too. No idea what the long term impact is, but I’m pondering ways to increase airflow to the transmission cooler and engine oil cost. I tried removing my front license plate but that didn’t do anything.
Transmission temps have been hotter than I’d like since I regeared to 4.88s. They’re about 15F hotter than before. Engine oil temp too. No idea what the long term impact is, but I’m pondering ways to increase airflow to the transmission cooler and engine oil cost. I tried removing my front license plate but that didn’t do anything.
So your pan temps stayed at or over 200° for the duration?
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- #1,408
Yep, at 70-75MPH.
When I had a stock front bumper (but was on 34s) I would see 196-198F consistently. Maybe it would approach 200F if ambient temps were in the upper 90s and I was at a few thousand feet of elevation (like eastern colorado or western nebraska).
With the winch bumper (and winch inside it), I would consistently see 200-202F. The ~5F difference never really concerned me.
Since re-gearing to 4.88s I consistently see 212-217F. It's typically around 212F when I'm doing 70, and creeps up further when I'm closer to 75. It runs lower when I'm doing 65 (probably 208F) and even lower below that. I run Mobil-1 75W-90 synthetic in the gears right now, though I may change that. I did try 75W-140 for a bit but A/T and engine oil temps were the same so I tend to think this is more about overcoming the drag that is being placed on the engine (particularly when towing)
Adding aluminum skids recently did not make any difference in the temp, FWIW.
It's not just transmission temps it's also engine oil temp. From what I've read it's expected that engine oil temp runs 230-250F, though I'm pretty sure back when I was stock it never exceeded 200F. I don't know where the engine oil temp sensor is though... is it before or after the engine oil cooler? Guess I should look that up.
I am planning to switch my engine oil to 5W-30 next change, given it's summer and I have a small oil leak on the front (probably the timing cover) so I'm hoping it might slow that down a bit. Will be curious to see if the oil viscosity plays a part (unlikely but I like to be scientific).
Trying to wrap my head around this. Helps that you're noting and capturing information.
Backing up and looking at this in totality, the 6.7 to 7.5 MPG (I assume corrected) may tell the story. The drivetrain is working hard to make power to tug the rig. The engine temp also being elevated supports that too.
Curious what your typical computed cruising HP at 75MPH is on level ground? Any change in temps between 4th or 5th? HP output should stay about the same. I'll have to go back and look at what my setup is doing there too.
I'll be putting in a tranny cooler hopefully in the next couple months. Looks like you might be able to benefit too. At least bringing down the tranny temps but it won't do anything for the engine temps.
If I were towing heavy with my 200, I would do this:
forum.ih8mud.com
The OP is in Egypt. Interested to know what parts he used.
I added a cooler to my Tundra. Toyota deleted the Tundra external transmission cooler in 2019, saying it's not needed, yet the previous tow package-equipped trucks all had one, and the 2019-2021 trucks use the same exact drivetrain.
The process is fairly simple. The only trick is making sure your transmission pan is level (for removing excess fluid after you add) and making sure the temp is in the 99-113ºF range when you add fluid to fill the new cooler. There is a process for shifting through all the gears to help circulate fluid, and then open the drain until the excess reduces to a trickle. I would think the process is similar with the 200.
I used Genuine Cooling Systems. He makes kits for the Tundra. I'm sure you could modify the bracket for the 200. An electric fan like the guy in Egypt added would be nice, too.
Transmission Cooler (Radiator) Upgrade
Been over a year now since I installed a larger transmission cooler with a thermostat and a cooling fan. Since I've had it running without trouble, thought I'd post it here.. could be useful for those towing or getting stuck in hot climates. Used to overheat transmission oil. Now, even with...
forum.ih8mud.com
The OP is in Egypt. Interested to know what parts he used.
I added a cooler to my Tundra. Toyota deleted the Tundra external transmission cooler in 2019, saying it's not needed, yet the previous tow package-equipped trucks all had one, and the 2019-2021 trucks use the same exact drivetrain.
The process is fairly simple. The only trick is making sure your transmission pan is level (for removing excess fluid after you add) and making sure the temp is in the 99-113ºF range when you add fluid to fill the new cooler. There is a process for shifting through all the gears to help circulate fluid, and then open the drain until the excess reduces to a trickle. I would think the process is similar with the 200.
I used Genuine Cooling Systems. He makes kits for the Tundra. I'm sure you could modify the bracket for the 200. An electric fan like the guy in Egypt added would be nice, too.
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- #1,412
Yeah mine came off, it wouldn't have done much if any good with the new bumper. I've thought about trying to make some sort of air "dam" (fairing) to direct some additional air over the existing cooler, just not sure how to do it with my setup. I don't know how much it would help much though, given the pre-gear change left me only a few degrees hotter. I mean I'd take a 5F drop for sure, but I don't think it'll pull me down 20F
If I were towing heavy with my 200, I would do this:
Transmission Cooler (Radiator) Upgrade
Been over a year now since I installed a larger transmission cooler with a thermostat and a cooling fan. Since I've had it running without trouble, thought I'd post it here.. could be useful for those towing or getting stuck in hot climates. Used to overheat transmission oil. Now, even with...
The OP is in Egypt. Interested to know what parts he used.
I added a cooler to my Tundra. Toyota deleted the Tundra external transmission cooler in 2019, saying it's not needed, yet the previous tow package-equipped trucks all had one, and the 2019-2021 trucks use the same exact drivetrain.
The process is fairly simple. The only trick is making sure your transmission pan is level (for removing excess fluid after you add) and making sure the temp is in the 99-113ºF range when you add fluid to fill the new cooler. There is a process for shifting through all the gears to help circulate fluid, and then open the drain until the excess reduces to a trickle. I would think the process is similar with the 200.
I used Genuine Cooling Systems. He makes kits for the Tundra. I'm sure you could modify the bracket for the 200. An electric fan like the guy in Egypt added would be nice, too.
Good stuff. Trying to gather strategies broadly as I look to add an additional cooler sequential to the OEM one. As simple as possible for weight and complexity, increasing transmission cooling, and without impacting engine cooling.
A more specific thread here
Tranny Cooler Upgrade Planning
EDIT: results in this thread https://forum.ih8mud.com/threads/diy-aux-transmission-cooler.1317943/#post-15063292 Not sure I've seen this done and could use some help brainstorming for an upgraded candidate transmission cooler. I'm towing outside of design parameters at 15,620 lbs total weight...
forum.ih8mud.com
We have an extended road trip coming up in a couple weeks with a lot of different towing conditions. I’ll have my wife take some data down along the way to have something to compare with yours. Different gears have been something we’ve been considering and the info you posted is interesting to me. We’re built and heavy but stock gearing 8 speed. I’ll report back after I get some data.
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- #1,415
Thanks. Fwiw it takes about 20 minutes or so if highway driving at 70+ before the temps really warm up and settle in. Around town my pan temp sits around 200F. I don’t know if the 8 speed will be different either
Is the torque converter locked in 5th gear?
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- #1,417
Yep that’s the green ring
I’m experiencing something I quite put my finger on. It’s likely feedback from my hitch, I have recently changed the entire tongue and coupler on my camper and this is the obvious suspect but I’m only experiencing it under specific conditions.
While towing uphill in 2nd or 3rd I feel a slight jerkiness while accelerating from 2000-2500 rpm’s. Once the rpm’s climb I do not feel this. Idk if it’s slight imperfections in the pavement giving me feedback through the hitch that goes away at a higher speed or something else fuel/air mix related or something along those lines.
No other issues or weirdness at any other speed or condition.
Any ideas or have I just been behind the wheel too much in the last couple days?
While towing uphill in 2nd or 3rd I feel a slight jerkiness while accelerating from 2000-2500 rpm’s. Once the rpm’s climb I do not feel this. Idk if it’s slight imperfections in the pavement giving me feedback through the hitch that goes away at a higher speed or something else fuel/air mix related or something along those lines.
No other issues or weirdness at any other speed or condition.
Any ideas or have I just been behind the wheel too much in the last couple days?
I have noticed the same on mine at the same load/ speed. I’ve really wondered if it’s a misfire, but it’s never thrown a light.. it’s done it a handful of times
I’ve read that the 5.7L pulls 10-13 degrees of timing on 87 fuel. It’s not a misfire, but under a load at RPMs that are below peak torque (which comes on at 3600rpm), it might be what you’re noticing?
