I've researched the range the transmission fluid wants to be in (<200°F) and I understand that some people may recommend locking out 5th gear but I guess my question is a bit more nuanced. The deal is, I had a shop flush the transmission and converter (flush not drain). So drain out the old, add fluid back and run through the gears, flush that, then add new again... something like 16 quarts when its all said and done. So that was fine but when I went to tow my 10ft single axle trailer with an empty weight of 950lbs and after being on the highway for maybe 15 minutes, I noticed the trans temp was really coming up into the 185 range. Kept driving and it momentarily went to 205 and thats when I put it into 4th (S drive or whatever) and it slowly settled out to 167°F where it stayed for the remainder of the 1.5 hour trip. So not really a problem per se but if I put my zero turn in the trailer and add another 750lbs there may be a heat issue especially in the summer. I guess I just thought being so far below the towing capacity of 5000lbs (I understand what all should go into that number and GCWR an so on) but towing 2000 pounds shouldn't heat up the fluid like that in my opinion. Ambient was maybe 55°F. If I need to get a trans cooler thats fine but was hoping I didn't need to as I was mostly going to stay below the 11,xxxx GCWR. So 3 day old fluid and pretty high temps. Does that sound in the realm of normal? If not are there any suggestions?
Towing Question
- Thread starter KF4R2011
- Start date
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Where are you measuring? Pan or Torque converter?
When watching temps pulling ~5000 lbs up a grade, I see ~250F at torque converter, ~225F at pan peak. Once I get to transmission lockup the temps come down below 200F. I have seen over 200F at the torque converter going up grades without a trailer. I have never seen torque converter lockup in 3rd gear, just 4th and 5th.
Probably 4,000 miles of towing and 65,000 miles total on original factory fill. Transmission still working fine. I will probably do a flush this month before another 1,000 mile round trip tow.
Just drive it, how many threads do you see on here about transmission failures?
When watching temps pulling ~5000 lbs up a grade, I see ~250F at torque converter, ~225F at pan peak. Once I get to transmission lockup the temps come down below 200F. I have seen over 200F at the torque converter going up grades without a trailer. I have never seen torque converter lockup in 3rd gear, just 4th and 5th.
Probably 4,000 miles of towing and 65,000 miles total on original factory fill. Transmission still working fine. I will probably do a flush this month before another 1,000 mile round trip tow.
Just drive it, how many threads do you see on here about transmission failures?
The temp changes were fairly dynamic so I’d say I’m measuring at the converter. I’m using OBD Fusion with the extended Toyota PIDs. There are 2 PIDs for trans temp and one of the other threads seemed to make the point that one is the pan and isn’t too dynamic while the other is what I’m seeing. I guess reading on various threads here and bobstheoilguy.com, my takeaway was the oil itself was to never get above 200-225 due to varnish issues and it gets worse from there. You make a good point about a general lack of failures... I suppose I don’t understand how 250 isn’t rapidly breaking down the fluid regardless of where it’s happening - in the TC vs sitting in the pan. For the record, my coolant temp never broke 197F. I’m used to that temp hovering around 210 or so.
I did a bit more "testing" as well as talking with a P.E. I work under and it would seem that there is an unseen factor in the mix with the higher trans temps that I was experiencing. The camper guys know this but I hadn't thought about the ramp on my utility trailer. The trailer is so light BUT anything over 10mph and the expanded metal ramp acts like a flat plate... or in other words a flat 5'x5' steel parachute. As a comparison I towed anther trailer that is a dual axle 8'x16' with a 750lb zero turn in it - so close to 3000lbs - in the city with stoplights and turns and generally slow speeds. There is one section that I drive about 55mph for a while but the point is that the trans. temps. didn't get over 147F. I suppose lightweight doesn't always equal "I should be able to tow that with no problem".
