I have a 2019 5th gen with a supercharger, 34's (soon going to 35's), 4.65 gears, and I am EXTREMELY heavy. I also have full skids (which don't help with tranny cooling). Since forever I had my transmission overheating like crazy. 250 was normal Offroad temps for me. 220 on highway I didn't bother to care anymore...
I posted a few threads about this. I have also met people on the trails that have similar issues. So I figured I'd share my experience and solutions:
1st I installed the CSF radiator. My engine temps are good but it promised to increase tranny cooling. It didn't work.
Then I drilled a ton of holes in thought out areas in my skids to increase airflow. That helped by a few degrees.
Then I installed a tranny cooler with a fan (to keep fan going when crawling). That helped a bit.
At this time I was still averaging 200 at highway flats. 220-230 on steep mountain passes. and 210 - 250 Offroad.
I would flush the tranny fluid after every 3-7 day trip (monthly). Half the time it would be burned only after 500 miles of [hard] Offroad driving.
*I flushed to spec (waited till 110 degrees on flat surface and drained excess out).
I then installed a second tranny cooler (with no fan). That helped substantially by lowering all the above specs by 10-15 degrees. However, I was not able to maintain normal temps all the time and once I got to 220+, it wasn't coming down until I stopped.
Magnuson SC gives you a tune for the SC. I contacted them a few times and always got the same answer... they will not customize the tune. I reached out to some tuners that are familiar with Magnuson and our industry and a custom tune was over 1.5K. Plus there is no guarantee it will work.
I was recommended modifying/installing aftermarket torque converter but the cost was over a few K. And no guarantee that it will work.
I purchased a cooler pump that would force the oil to move through the coolers faster and help cool faster. I was warned it may ruin the stock torque converter so I held off on installing it. I figured once my tranny get's worse (as it was already acting funky with only 18K miles)... I would see if the Cooler pump works. If not, I will need a new tranny anyways and at that time can install the aftermarket torque converter for cheap as the tranny will be out anyways.
Then I talked to a friend who works at a cement factory and told me how they have a ton of HD machinery that runs extremely hot. The way they keep operating temps for the oil is by putting in less oil than recommended...
So... I figured why not. I did a full flush (my 6th time!) and put in the exact amount of oil recommended by Toyota (110 degrees, flat ground, remove excess oil...). I drove around for a day and then went back to my tranny and removed a about 3/4 of quart (I was aiming for 1/2 but why not...).
Then the weirdest thing happened... my tranny is now running very cool. I did about 900 miles to Baja and back home after this experiment. I did 500 Offroad miles in the mountains that normally I would be running 250 degrees.
On flat pavement now I am running around 160. On mountain passes on pavement I can't get it about 190. Offroad I am running 180 on average at high speeds where before I would hit 230+. When pushing her hard Offroad I touched 220 once in Baja. Whereas I would have been at 250 1/2 that day in Baja before.
Now I think I may have too many tranny coolers!!
IDK if this will help anyone or is useful information. I don't know exactly why this worked for me or if it will work for you. However, I figured I'd share this as I was at a point where I already made peace with getting a new tranny soon...
FYI... all my tranny clunks and weird shifts also went away...
I posted a few threads about this. I have also met people on the trails that have similar issues. So I figured I'd share my experience and solutions:
1st I installed the CSF radiator. My engine temps are good but it promised to increase tranny cooling. It didn't work.
Then I drilled a ton of holes in thought out areas in my skids to increase airflow. That helped by a few degrees.
Then I installed a tranny cooler with a fan (to keep fan going when crawling). That helped a bit.
At this time I was still averaging 200 at highway flats. 220-230 on steep mountain passes. and 210 - 250 Offroad.
I would flush the tranny fluid after every 3-7 day trip (monthly). Half the time it would be burned only after 500 miles of [hard] Offroad driving.
*I flushed to spec (waited till 110 degrees on flat surface and drained excess out).
I then installed a second tranny cooler (with no fan). That helped substantially by lowering all the above specs by 10-15 degrees. However, I was not able to maintain normal temps all the time and once I got to 220+, it wasn't coming down until I stopped.
Magnuson SC gives you a tune for the SC. I contacted them a few times and always got the same answer... they will not customize the tune. I reached out to some tuners that are familiar with Magnuson and our industry and a custom tune was over 1.5K. Plus there is no guarantee it will work.
I was recommended modifying/installing aftermarket torque converter but the cost was over a few K. And no guarantee that it will work.
I purchased a cooler pump that would force the oil to move through the coolers faster and help cool faster. I was warned it may ruin the stock torque converter so I held off on installing it. I figured once my tranny get's worse (as it was already acting funky with only 18K miles)... I would see if the Cooler pump works. If not, I will need a new tranny anyways and at that time can install the aftermarket torque converter for cheap as the tranny will be out anyways.
Then I talked to a friend who works at a cement factory and told me how they have a ton of HD machinery that runs extremely hot. The way they keep operating temps for the oil is by putting in less oil than recommended...
So... I figured why not. I did a full flush (my 6th time!) and put in the exact amount of oil recommended by Toyota (110 degrees, flat ground, remove excess oil...). I drove around for a day and then went back to my tranny and removed a about 3/4 of quart (I was aiming for 1/2 but why not...).
Then the weirdest thing happened... my tranny is now running very cool. I did about 900 miles to Baja and back home after this experiment. I did 500 Offroad miles in the mountains that normally I would be running 250 degrees.
On flat pavement now I am running around 160. On mountain passes on pavement I can't get it about 190. Offroad I am running 180 on average at high speeds where before I would hit 230+. When pushing her hard Offroad I touched 220 once in Baja. Whereas I would have been at 250 1/2 that day in Baja before.
Now I think I may have too many tranny coolers!!
IDK if this will help anyone or is useful information. I don't know exactly why this worked for me or if it will work for you. However, I figured I'd share this as I was at a point where I already made peace with getting a new tranny soon...
FYI... all my tranny clunks and weird shifts also went away...
