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oceanblue2019

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The ZF 8 speed has an internal temp bypass switch and by design likes to run a bit hotter then other autos.
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thrasher

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For the almost 3 years and 70k miles we have had my wife's Jeep and I have monitored temps of oil, tranny and coolant and the numbers you are seeing are normal. We have done 3 cross country trips, wheeled in the hot summer temps of UT and at the high elevations of Ouray. Just cruising along the highway it will hang in the high 190s to 200ish. Climbing hills or hard wheeling it will hit the 210 - 215 mark, maybe even more and then come back down. Interesting to note all temps ran COOLER in Moab at 95 degree ambient temps vs. 50 degree ambient temps in Ouray at 10k feet. I've had a pan drop and fluid/filter change done at around 64k miles and everything looked good. So what you are seeing is what I have seen for many miles with no problems.
I was at 250+ with light to medium wheeling
 

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I was at 250+ with light to medium wheeling
Ouch! The highest I ever recall seeing was like 222 and by then the fan was on full blast. Sorry if I missed that part in the thread, that is freaking high I would say.
 

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Recently my Jeep has unfortunately spent more time in the shop than it has on the road it started with two trips to fix leaking oil and has recently ended with the transmission overheating and a check engine light.
You mentioned earlier that the check engine light came on, is that no longer happening?

Are you just monitoring the temps and randomly pulling over when it reaches 250?
 

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thanks for digging in, this is really good info
No problem, learning too.
Here's one link I gleaned info from:

http://perception.fcaperformanceinstitute.com/FCARepository_con/topiccontent/1588106484/0221308.pdf

If I were to have a tranny steady pegging 250 I'm thinking a couple of things.

1st is the tranny is very top notch, so I wouldnt immediately point trouble in that direction even though possible. Thinking more likely a sensor reporting wrongly. Next maybe the external cooler bypass isnt working properly and the reason so high.

Per what I read at 248 it says that is considered extreme temperature and the tranny reacts by adjusting shift points with no mention of throwing codes.

I would push the dealer, anything labeled extreme is not normal and it appears no other jeep is doing this. Maybe another dealer, or escalate the problem.
 

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No problem, learning too.
Here's one link I gleaned info from:

http://perception.fcaperformanceinstitute.com/FCARepository_con/topiccontent/1588106484/0221308.pdf

If I were to have a tranny steady pegging 250 I'm thinking a couple of things.

1st is the tranny is very top notch, so I wouldnt immediately point trouble in that direction even though possible. Thinking more likely a sensor reporting wrongly. Next maybe the external cooler bypass isnt working properly and the reason so high.

Per what I read at 248 it says that is considered extreme temperature and the tranny reacts by adjusting shift points with no mention of throwing codes.

I would push the dealer, anything labeled extreme is not normal and it appears no other jeep is doing this. Maybe another dealer, or escalate the problem.
Bob, I too am wondering if it’s a temperature sensor issue. If it is, it may adjust shift points needlessly.
 
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thrasher

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You mentioned earlier that the check engine light came on, is that no longer happening?

Are you just monitoring the temps and randomly pulling over when it reaches 250?

Yes last few times ive taken it off road (or sitting in a drive through lane at 60 degrees) you can hear the fan kick on and i pull up the transmission temp and watch it just keep climbing
 

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Hi,

So happy I found this conversation.

I have 2021 jl with 11k miles on it.
After changing for 35s and small lift kit I did notice my transmission is getting over 250f when offroad. After couple of times I did go to the dealer, showed them the temp we got and the took the jeep for 4 days, called back said nothing is worng and there nothing that need to be done...
I went to tons of places and ask a lot off professional and people their opinion about this and thay all said its hot. The fluid is probably burned already in this temperature.
Called the dealer again and asked them to replace the fluid, they said there is no reason to do so. Just like you when off roading i feel its kind of stupid to stop and wait to get to 220f.

After researching alot about this I did go ahead and purchased the mishimoto cooler, I received it on Friday and today, 12/13/21, I took it to my mechanic to install it, once I get the jeep I'm planing to see if its helping and how much if so..
I planing on taking the jeep back to the dealer next week to replace the fluid.

Ill keep you posted about everything.
 

oceanblue2019

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The issue is the cooler is only used when the fluid goes above the temperature the transmission is programmed to open the control solenoid to the cooler. I heard this was programmed to around 255 degrees so pretty hot already - it is an emergency action to open the cooling loop.

A better way is an aftermarket pan like in the link. It holds 2.5 quarts of added fluid and the aluminum construction and fins likely help with cooling.


https://www.ppepower.com/shop/heavy...n-jl-jt-jeep-wrangler-850re-transmission.html
 

roaniecowpony

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Hi,

So happy I found this conversation.

I have 2021 jl with 11k miles on it.
After changing for 35s and small lift kit I did notice my transmission is getting over 250f when offroad. After couple of times I did go to the dealer, showed them the temp we got and the took the jeep for 4 days, called back said nothing is worng and there nothing that need to be done...
I went to tons of places and ask a lot off professional and people their opinion about this and thay all said its hot. The fluid is probably burned already in this temperature.
Called the dealer again and asked them to replace the fluid, they said there is no reason to do so. Just like you when off roading i feel its kind of stupid to stop and wait to get to 220f.

After researching alot about this I did go ahead and purchased the mishimoto cooler, I received it on Friday and today, 12/13/21, I took it to my mechanic to install it, once I get the jeep I'm planing to see if its helping and how much if so..
I planing on taking the jeep back to the dealer next week to replace the fluid.

Ill keep you posted about everything.
I'm interested to see if this cures your high temps. If you had a sticking thermal bypass valve does removing and replacing the OEM cooler eliminate the OEM bypass valve as part of the OEM cooler assembly? Or is the thermal bypass in the transmission?
 

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Recently my Jeep has unfortunately spent more time in the shop than it has on the road it started with two trips to fix leaking oil and has recently ended with the transmission overheating and a check engine light. Picking it up this last time I was informed that the transmission getting to 250+ degrees was working within standards and no need to concern and to just pull over if it gets too hot. Problem is last offroading trip I had to pull over three times because it would climb above 250 and continue to climb without cooling itself. 45min later after watching the temp get back to normal we could continue. The dealership is refusing to fix anything as "nothing is broken" although they were able to reproduce it getting too hot and will not look at it again until I boil it so much it goes into limp mode
1. Anyone else having issue with being in 4wd offroading and the transmission refusing to stay cool
2. Any advice for how to deal with the dealership as pulling over while offroading or on the interstate isnt really a solution
Trade it. And get a manual transmission on the next one. :)
 

heamick

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Recently my Jeep has unfortunately spent more time in the shop than it has on the road it started with two trips to fix leaking oil and has recently ended with the transmission overheating and a check engine light. Picking it up this last time I was informed that the transmission getting to 250+ degrees was working within standards and no need to concern and to just pull over if it gets too hot. Problem is last offroading trip I had to pull over three times because it would climb above 250 and continue to climb without cooling itself. 45min later after watching the temp get back to normal we could continue. The dealership is refusing to fix anything as "nothing is broken" although they were able to reproduce it getting too hot and will not look at it again until I boil it so much it goes into limp mode
1. Anyone else having issue with being in 4wd offroading and the transmission refusing to stay cool
2. Any advice for how to deal with the dealership as pulling over while offroading or on the interstate isnt really a solution
I had 2018 JLRU auto, and the trans ran hot, I called jeep, no help, I put a aux cooler on it
it did not help much,, Jeep said th

  • ere is a thermostat inside the trans, such BS, Jeep got totaled out, got a new 2021 same equipment,, to trans cooling problems, Jeep changed the cooling lines by =going to a larger die tubing, the cooling does not go to the trans but a Mishimoto united right under the radiator cover, big difference.
 

roaniecowpony

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I had 2018 JLRU auto, and the trans ran hot, I called jeep, no help, I put a aux cooler on it
it did not help much,, Jeep said th

  • ere is a thermostat inside the trans, such BS, Jeep got totaled out, got a new 2021 same equipment,, to trans cooling problems, Jeep changed the cooling lines by =going to a larger die tubing, the cooling does not go to the trans but a Mishimoto united right under the radiator cover, big difference.
? I'm not sure what was stated.
 

roaniecowpony

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I was at 250+ with light to medium wheeling
Maybe bring an IR thermometer along on your next outing to get a temperature of some lines and the transmission case in some areas and compare them to a jeep in your group. That might tell you if you have an erroneous sensor or actually have an overheat condition.
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