ZF 8 sp transmission temperature

[RubiconHemi]

Hi, this does not apply to the 392 transmission. 1. The 392 trans is special, it was built in Germany. The one in this video is built in the US. 2. The 392 transmission cooling system is set up totally different. My guess is you don't have a 392? Feel free to remove the video, so it doesn't create any confusion. Thank you.

 

[Infidel09]

What are most of the 392 owners seeing for transmission temperature when driving on the interstate? My transmission gets up to between 195-200 degrees after running at 65 mph for over 20 minutes. That doesn’t seem bad; however, I have the same transmission in my Ram 2500 6.4L 8 speed ZF runs less than 180 degrees under the same conditions. It never gets to 190, even when towing. I know the Ram has a transmission oil cooler and not sure if the Wrangler does. That may be the difference. Anyone seeing similar temps on their 392 Wranglers and/or know if the Jeep has a tranny cooler?

If you have more than 60k miles on the jeep you should consider a transmission flush with filter change. My temps dropped and shifts are nice and crisp again..

 

[Mud]

Hi, this does not apply to the 392 transmission. 1. The 392 trans is special, it was built in Germany. The one in this video is built in the US. 2. The 392 transmission cooling system is set up totally different. My guess is you don't have a 392? Feel free to remove the video, so it doesn't create any confusion. Thank you.

I had a 2021, and I have a 2023 now.

 

[Un4seen4]

If you have more than 60k miles on the jeep you should consider a transmission flush with filter change. My temps dropped and shifts are nice and crisp again..

this is my next project (all be it, reluctantly) along with a PPE 'normal' +1 Qt pan.

idk why but doing idea of doing the flush/drain-fill on our trans makes me really nervous

 

[Keithbickford]

Thanks! I am not inclined to remove the thermostat/bypass feature. It’s gotta be there for a reason - one that I don’t currently comprehend. I understand that without a thermostat all of the fluid is flowing the entire time and will stay cooler, longer. And I understand the thermostat is there to keep it at operating temperature and limit the fluid flow during warm up. And I also notice, on both the Ram and Wrangler - it takes a lot of driving to get the transmission temperature above 170. So for some reason, the Jeep engineers want to keep the tranny at 190-200 degrees when fully warmed up with and Ram engineers don’t care? The only difference is the Jeep might warm up quicker with the thermostat/bypass feature?

I speculate all fluid temps are kept higher for efficiency (MPG ratings) as warmer thinner fluid reduces drag. But does that compromise longevity? That’s the unknown.
I’ve not concerned myself with transmission temperatures, but I’m concerned about 260°F engine oil temperatures. I think our Jeeps would benefit from a true external oil cooler.

 

[Un4seen4]

I speculate all fluid temps are kept higher for efficiency (MPG ratings) as warmer thinner fluid reduces drag. But does that compromise longevity? That’s the unknown.
I’ve not concerned myself with transmission temperatures, but I’m concerned about 260°F engine oil temperatures. I think our Jeeps would benefit from a true external oil cooler.

I believe you are on the money with the thinner oils for efficiency, if i recall correctly the newer GM 6.2 V8s that had a bunch of crank bearing issues was solved by moving to a heavier weight oil.

I would also argue that while our over all coolant/oil temps are higher, most likely done at the 0.0001% gain in efficiency, they are in the 'functional range' of the fluid. Granted its at the sacrifice of longevity of said fluids but I would hope or at least id like to think that is the way they designed the whole to operate at the higher end of the operational range of the various fluids.

Which also brings the follow up question of: if so on the purposeful higher temps, would lowering them by a significant margin cause any issues in the system?

butttt.... i do agree that seeing temps at like 220 for water, 250 oil and 200 trans makes me nervous and want to do something about it.