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Question for those monitoring trans temps

Discussion in '2.5 Gen Tundras (2014-2021)' started by Joe333x, May 24, 2021.

  1. May 24, 2021 at 11:08 PM
    #1
    Joe333x

    Joe333x [OP] Member

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    I have been monitoring my trans fluid pan temps since I got the truck. I have noticed that if I keep the truck in S4 in the city and and don't go over 65 on the highway I dont see temps over 220 which is when the thermostat would normally open for the trans cooler anyway. Has any one else come to this conclusion? Im guessing maybe Toyota tested the truck with no trans cooler with a speed limit of 65? I only towed a boat once and kept it in S4 and at 65 and didnt see temps over 220 either. Maybe the solution if you dont want to add a trans cooler is keep it under 65 and S4 in the city? Curious what others who regularly watch their temps have seen. Side note driving in S4 in the city and S5 on the highway at 65 dont seem to have much effect on mpg either.
     
  2. May 24, 2021 at 11:24 PM
    #2
    helidave

    helidave hellacopter

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    At least on my truck, the torque converter locks up and stays locked in 4th compared to 5th and 6th where it unlocks with even light throttle input. This makes a huge difference in trans/converter temps.
     
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  3. May 24, 2021 at 11:30 PM
    #3
    Terndrerrr

    Terndrerrr guzzling dealer repellent

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    The thermostat opens when the pan reaches 190°-195°F. My pan temp usually hovers around there. When you’re cruising at a consistent speed on fairly level terrain, your TC stays locked, which does not generate heat nearly as much as when it’s unlocked.

    The interesting thing I’ve noticed is that my engine coolant can get up to 185°F in a few minutes, but my transmission won’t catch up for 30 min or longer. I thought the hockey puck warmer was supposed to do that quickly.
     
  4. May 24, 2021 at 11:41 PM
    #4
    Joe333x

    Joe333x [OP] Member

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    Are you positive on the 190-195? I had read the thermostat doesnt open til 220 and then closes again when temp are back to 190~, that would operate like most cooler systems which kick in at 220. The coolant reaches temp faster because water heats faster than oil. I watch the engine oil and trans temps and the oil and trans stay about the same all the time. The warmer is used to get the oils up to 60° as quickly as possible. What is odd is no one cares to add an oil cooler even though the engine oil and trans oil temps basically mimic each other by a degree or two.
     
  5. May 25, 2021 at 4:21 AM
    #5
    batman900

    batman900 Yep

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    Takes forever for the trans to warm up. On my 13 mile commute each way to work the hottest I've seen is 190. On my trip last weekend from OK to Austin TX the hottest it hit was 215F in some stop and go traffic otherwise it hovered around 208F running 85mph loaded with around 600lbs of people and suit cases at a temp of 90F outside. I've messed around with S4 and speeds, under 70mph and S4 is definitely where it's happiest. The back roads highway around here is 65mph and while towing a 2k trailer of brush and limbs (probably 3k total) in S4 the hottest I saw was 190-200ish. I imagine with temps getting up to 105F here in summer, I will be hitting around 225F on the main highway unloaded running 85mph or about the same temp towing on the backroads highway at 65mph. Basically as long as I don't decide I need to tow on the main highway I think I'll be fine.
     
  6. May 25, 2021 at 4:27 AM
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    Tundra234

    Tundra234 New Member

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    Just add a tranny cooler and don't worry about it. With my cooler, I towed about 5,000 lbs in regular drive, city traffic, and my temp averaged 192.
     
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  7. May 25, 2021 at 5:43 AM
    #7
    Mad Max

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    Thermostat is 185 to 190 on transmission. I tow in D with 5Klb boat at 72 mph and stay about 198F in Souteast texas. Playing with S4 and staying below 60mph. fk that. I almost get run over at 72 mph!!!!!
     
  8. May 25, 2021 at 8:08 AM
    #8
    jordoncloutier

    jordoncloutier New Member

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    Towing my 6000lb travel trailer , 80 degree ambient temps , after I installed the trans cooler on my 19" CM the pan temps stay around 200 degrees , I tow in S5 with tow/haul on
     
    Last edited: May 25, 2021
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  9. May 25, 2021 at 8:23 AM
    #9
    tttrdpro

    tttrdpro Former Naval Person

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    I tow in D with tow/haul engaged. I have no idea what the transmission temp is doing. I’ve never bothered to check.
     
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  10. May 25, 2021 at 8:29 AM
    #10
    Terndrerrr

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    Yes, the thermostat is supposed to open around 190 @ the pan and stay that way until the pan cools down below that. Monitoring mine, I don’t notice the rush of cooled fluid into the trans until it hits closer to 195. But that might be because of slight inaccuracies in the sensors or the Fusion app I’m using.

    Yeah, drivers are insane around here, too. I blame the CA exodus. 15 years ago, most people did 10 under the limit around here (equally dangerous and frustrating). For what it’s worth, the manual specifies to tow in S4. If you ever have any issues under warranty (prob unlikely), you’re gonna want to be able to tell your dealer you only tow in S4.
     
    Joe333x[QUOTED][OP] likes this.
  11. May 26, 2021 at 9:51 AM
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    SSPey

    SSPey .

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    I see the same thing, because I don’t do much highway driving except for trips. However, pan temps do rise quickly to 220F at 60 mph with light towing (3500 lbs for 30 mins) in 50-70F ambient. With hotter 90-100F ambient coming soon, and longer heavier towing, through mountains, I expect staying under 220F will be wishful thinking.
     
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  12. May 26, 2021 at 10:29 AM
    #12
    crewmaxlmt

    crewmaxlmt How dare you!

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    Driving around town towing 3500 - 5000 pounds, I am seeing temps from 220-240. Never below 220.
     
  13. May 26, 2021 at 6:35 PM
    #13
    2mchfun

    2mchfun Yeah it'll pull it, just don't expect to stop!

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    I put a cooler on and keep it pinned open. Pretty consistent at about 190.
     
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  14. May 26, 2021 at 7:12 PM
    #14
    Cfincke

    Cfincke Mall Crawler but capable

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    My daily driving on the highway i see temps of 185-190 when I am arriving at work after 20 minutes of 75+mph driving.
    When towing our 26ft travel trailer in S4 at 70mph my trans temp is right under 200 degrees. It only goes above 200 on hills or when accelerating from a stop.
     
  15. May 30, 2021 at 8:54 AM
    #15
    blanchard7684

    blanchard7684 New Member

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    I didn't capture it precisely but yes S4 seems almost like a cool-down mode. If my memory serves I was able to hit as low as 198 in S4 at 65 mph in ambients of around 50deg.

    I agree with your point about the engine oil cooler.

    Check out the new Dodge Rams... and their engine oil temps are astonishingly high.
     
    Joe333x[QUOTED][OP] likes this.

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