Hot Transmission

[Dotan swisa]

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?

Hi,

We install the mishimoto cooler, no need to replace the bypass valve we replacing the cooler. It didn't help.
I called zf technician, very helpful I must say, the told me that the temp i get are not supposed the reach this level even when off roading, i have 37" on 4.5 long arm kit, even with this setup zf tech guy said not supposed to reach this temperature. He said that the issue is somewhere with the cooling system that is not letting the oil to reach to the front cooler. I took the jeep the transmission place to diagnose, cost me $150, they drove the car and brought the transmission to 240f. Oil levels all good, temperature gauge read accurate temperature, front cooler pipe are cold meaning they operate good, the issue we found is that there is no oil in the cooler, the oil doesn't reach to to cooler to cool down. On the side off the transmission there is another small cooler with a valve, when the temp are high this valve suppose to open and let the oil flow to the front cooler, by comparing the temperature of the front cooler pipes which was cold and the temp of the pipe where the actual transmission whice was hot we believe that the issue is with this valve that not opening to the let the oil flow..

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[Dotan swisa]

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?

So I ended up ordering new transmission bypass heater. We installed it today. The new part DOESN'T have the bypass valve in it, they redesign this heater.

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?

So I ended up ordering and installing new transmission heater for the jeep, mopar part 68485460AB. When I received this part by mail I notice it look different then the the heater that the jeep came with from the dealer. The heater they send me have NO bypass valve in it.. my transmission doesn't pass 195 - 205F after installing the new part, on road or off road. Its just unbelievable. transmission heater cost me $150 after tax and delivery install was $450 (didn't install it at the dealer).

Apparently for "some" reason Part #68485460AB is replacing part #68233384AB which is the original transmission heater came with the jeep..


Attached is a picture of the old transmission heater, the bypass valve is where the mark is.. if your transmission is getting hot this pc might be the reason and that's exactly what ZF technician told me over the phone when I started asking questions about why my transmission is getting so hot.
Again, the new part does not have this valve there.

This is the link for mopar where its also mention part 68485460AB is replacing part 68233384AB. I would call them and give them vin number just to confirm it's actually fit to your jeep.

https://www.moparpartsinc.com/p/jeep__Wrangler/HEATER-TRANSMISSION/94853043/68485460AB.html

 

[thrasher]

So I ended up ordering new transmission bypass heater. We installed it today. The new part DOESN'T have the bypass valve in it, they redesign this heater.



So I ended up ordering and installing new transmission heater for the jeep, mopar part 68485460AB. When I received this part by mail I notice it look different then the the heater that the jeep came with from the dealer. The heater they send me have NO bypass valve in it.. my transmission doesn't pass 195 - 205F after installing the new part, on road or off road. Its just unbelievable. transmission heater cost me $150 after tax and delivery install was $450 (didn't install it at the dealer).

Apparently for "some" reason Part #68485460AB is replacing part #68233384AB which is the original transmission heater came with the jeep..


Attached is a picture of the old transmission heater, the bypass valve is where the mark is.. if your transmission is getting hot this pc might be the reason and that's exactly what ZF technician told me over the phone when I started asking questions about why my transmission is getting so hot.
Again, the new part does not have this valve there.

This is the link for mopar where its also mention part 68485460AB is replacing part 68233384AB. I would call them and give them vin number just to confirm it's actually fit to your jeep.

https://www.moparpartsinc.com/p/jeep__Wrangler/HEATER-TRANSMISSION/94853043/68485460AB.html

This sounds incredibly promising. ordering this today

 

[Rodeoflyer]

Those bypass deletes work.. I have one in the truck. Trans runs much cooler now https://www.dieselpowerproducts.com/ats-thermal-bypass-valve-67l-ram

 

[Silver&Black]

So I ended up ordering new transmission bypass heater. We installed it today. The new part DOESN'T have the bypass valve in it, they redesign this heater.



So I ended up ordering and installing new transmission heater for the jeep, mopar part 68485460AB. When I received this part by mail I notice it look different then the the heater that the jeep came with from the dealer. The heater they send me have NO bypass valve in it.. my transmission doesn't pass 195 - 205F after installing the new part, on road or off road. Its just unbelievable. transmission heater cost me $150 after tax and delivery install was $450 (didn't install it at the dealer).

Apparently for "some" reason Part #68485460AB is replacing part #68233384AB which is the original transmission heater came with the jeep..


Attached is a picture of the old transmission heater, the bypass valve is where the mark is.. if your transmission is getting hot this pc might be the reason and that's exactly what ZF technician told me over the phone when I started asking questions about why my transmission is getting so hot.
Again, the new part does not have this valve there.

This is the link for mopar where its also mention part 68485460AB is replacing part 68233384AB. I would call them and give them vin number just to confirm it's actually fit to your jeep.

https://www.moparpartsinc.com/p/jeep__Wrangler/HEATER-TRANSMISSION/94853043/68485460AB.html

Hey think I’m having the same heating issues. I have a 2.0 sport A/T. Do you think this will help ? I’m wondering if it’ll fit mine.

 

[Dotan swisa]

Hey think I’m having the same heating issues. I have a 2.0 sport A/T. Do you think this will help ? I’m wondering if it’ll fit mine.

Hi,

If this is this is the issue you have this part will fix it 100%.
I did a lot of investigation before I replaced it and the only thing that go go worng with my Issue wast this bypass heater.

I can express enough how happy I am for doing thing this. My transmission is not going over 205 In any situation, off roan on road , crawling. It's just unbelievable to see this.

If you decide to to it I suggest you call the service line and give them your vin number to see if this part actually fit your jeep.

I highly recommend it.

 

[Silver&Black]

Hi,

If this is this is the issue you have this part will fix it 100%.
I did a lot of investigation before I replaced it and the only thing that go go worng with my Issue wast this bypass heater.

I can express enough how happy I am for doing thing this. My transmission is not going over 205 In any situation, off roan on road , crawling. It's just unbelievable to see this.

If you decide to to it I suggest you call the service line and give them your vin number to see if this part actually fit your jeep.

I highly recommend it.

That’s awesome ! Thanks for the reply. I wonder if the engineers decided to change this for 2020 +. I have a 2019

 

[Jeepskiy]

Hello, I have a 21 Rubicon. 3.6 with 850RE. My transmission temps have always been in 220-230s. At 17K miles I needed up burning up the transmission driving on freeway. Dealer replaced the transmission and transmission oil cooler under warranty, now the temps are 230-240. Dealer said that those temps are normal.

 

[CarbonSteel]

When at full engine operating temperature on the highway, the coolest I have ever seen the transmission is 190°F, but I typically run 203°F - 208°F going down the highway even in the mountains.

I have seen a high temperature of 240°F while off-roading at high elevations where I am moving slowly and the Jeep is pulling hard to climb.

With that said, 250°F for any sustained length of time is too high. The fluid in ZF8 transmissions has a synthetic blend base stock and not full synthetic and while 250°F is not in the danger zone, it is "up there" and over time sustaining that temperature will cause the fluid to begin to break down and will require changing more frequently.

 

[roaniecowpony]

Hello, I have a 21 Rubicon. 3.6 with 850RE. My transmission temps have always been in 220-230s. At 17K miles I needed up burning up the transmission driving on freeway. Dealer replaced the transmission and transmission oil cooler under warranty, now the temps are 230-240. Dealer said that those temps are normal.

In looking at the parts lists for the transmission, it shows a "heater", which looks like may have a thermostat built in to it. That would be on my list of suspects. Another possibility is an issue with the Powertrain Control Module.

 

[Jeepskiy]

In looking at the parts lists for the transmission, it shows a "heater", which looks like may have a thermostat built in to it. That would be on my list of suspects. Another possibility is an issue with the Powertrain Control Module.

I wonder if that comes with the new transmission as assembly or if they swapped it over from the old one.

 

[roaniecowpony]

I wonder if that comes with the new transmission as assembly or if they swapped it over from the old one.

I suppose it depends on how bad the problem is. Hard cut-in changes happen when the issue is intolerable. If it's a low percentage issue, a soft cut-in for production would be more likely. Soft cut-ins would use existing stock until depletion, but all new manufacturing orders of the component would be the new part. Hard cut-ins purge all the stock at warehouses and in production system, and sometimes stock at dealers. There's variations to these two cut-ins. The cost of hard cut-ins can be huge, depending on inventory and delays to production.

 

[roaniecowpony]

I ordered the new Heater-valve assembly 68485460AB yesterday. They're now $65 at Mopar Parts Giant 68485460AB - Mopar Parts Giant I will also look into eliminating the heater portion of this. The heater is intended to warm up the fluid to operating temperature quickly. But I live in a warm climate and hate the cold. So, not much chance of me needing a pre-heat for the transmission fluid.

I just recently eliminated the thermostat in my GMC truck 6L80 transmission, which was also known to cause high fluid temps. That mod dropped my normal operating fluid temperatures by about 30-40 degrees. Those transmission were never equipped with thermostats for many years, until my model year.

 

[Jeepskiy]

Hi,

We install the mishimoto cooler, no need to replace the bypass valve we replacing the cooler. It didn't help.
I called zf technician, very helpful I must say, the told me that the temp i get are not supposed the reach this level even when off roading, i have 37" on 4.5 long arm kit, even with this setup zf tech guy said not supposed to reach this temperature. He said that the issue is somewhere with the cooling system that is not letting the oil to reach to the front cooler. I took the jeep the transmission place to diagnose, cost me $150, they drove the car and brought the transmission to 240f. Oil levels all good, temperature gauge read accurate temperature, front cooler pipe are cold meaning they operate good, the issue we found is that there is no oil in the cooler, the oil doesn't reach to to cooler to cool down. On the side off the transmission there is another small cooler with a valve, when the temp are high this valve suppose to open and let the oil flow to the front cooler, by comparing the temperature of the front cooler pipes which was cold and the temp of the pipe where the actual transmission whice was hot we believe that the issue is with this valve that not opening to the let the oil flow..

I do believe after doing some comparing to other jeeps (my wife’s and coworkers) that the front top cooler pipe is the return fluid that’s supposed to be cold and the bottom cooler pipe is fluid going in and should be hot/warm. Both of the pipes on my jeep are cold after getting the temperature up to 240. So I’m pretty sure my heater bypass isn’t working.

 

[Dotan swisa]

I do believe after doing some comparing to other jeeps (my wife’s and coworkers) that the front top cooler pipe is the return fluid that’s supposed to be cold and the bottom cooler pipe is fluid going in and should be hot/warm. Both of the pipes on my jeep are cold after getting the temperature up to 240. So I’m pretty sure my heater bypass isn’t working.

Hi,

Try to replace the heater, I'm sure you will never see 240f again.
When I had the issue 8 called ZF technical support and the tech guy told me that the heater valve should get fully open once reach to 180f. He said healthy temp for this transmission is 180f to 220/230f.
He was the one who actually told me that the issue I have is for sure the heater valve..
I'm towing smittybilt scout ovarland trailer with 4 person tent on it and water tank, never got more then 208f since I replace this part.

Good luck.

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