Transmission cooler
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Actually the confusion over the transmission Aux cooling from 2014 to present is well founded.
Different configurations/options had it like Tow Group, AD2, and all Trail Hawks.
A few thoughts:
All transmissions in all vehicles I have ever had going back 40 years have had transmission cooling lines running to the bottom of the radiator. That is the standard cooling for the transmission.
If a mini radiator is added to the radiator that could very well constitute HD trans. cooling. No different than the vehicle's air conditioning coils you will find attached to your radiator.
Also the size of that trans. cooling unit could also differentiate STD or HD cooling. More air flow equals better cooling.
I would guess that it is very possible that after the transmission fiasco of 2014 and 2015 models FCA decided it was much cheaper in the long run to spend the few bucks and put aux coolers on all models or all V6 models. That is to protect the compact ZF transmission from over heating and damaging the lifetime fluid. In the old days transmission fluid got changed out on a maintenance schedule early especially when towing.
Towing 2,000lbs or less would be a cake walk for the Cherokee, especially with a V6. And that is with standard equipment.
Also there are add on aftermarket Aux transmission coolers available for the Cherokee that a good transmission shop could put on that would enhance protection especially if you are towing very heavy.
*** Also the big point to remember is transmission fluid is not lifetime at that point when you tow in my opinion. Depending how you tow, weight you tow, and frequency you tow will all determine how early you will need to change. All my previous Jeeps had a schedule for towing or severe service maintenance. This one seems to be hard to find.
Different configurations/options had it like Tow Group, AD2, and all Trail Hawks.
A few thoughts:
All transmissions in all vehicles I have ever had going back 40 years have had transmission cooling lines running to the bottom of the radiator. That is the standard cooling for the transmission.
If a mini radiator is added to the radiator that could very well constitute HD trans. cooling. No different than the vehicle's air conditioning coils you will find attached to your radiator.
Also the size of that trans. cooling unit could also differentiate STD or HD cooling. More air flow equals better cooling.
I would guess that it is very possible that after the transmission fiasco of 2014 and 2015 models FCA decided it was much cheaper in the long run to spend the few bucks and put aux coolers on all models or all V6 models. That is to protect the compact ZF transmission from over heating and damaging the lifetime fluid. In the old days transmission fluid got changed out on a maintenance schedule early especially when towing.
Towing 2,000lbs or less would be a cake walk for the Cherokee, especially with a V6. And that is with standard equipment.
Also there are add on aftermarket Aux transmission coolers available for the Cherokee that a good transmission shop could put on that would enhance protection especially if you are towing very heavy.
*** Also the big point to remember is transmission fluid is not lifetime at that point when you tow in my opinion. Depending how you tow, weight you tow, and frequency you tow will all determine how early you will need to change. All my previous Jeeps had a schedule for towing or severe service maintenance. This one seems to be hard to find.
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MY trailhawk 2015 has an external transmission oil cooler, and a dual fan behind the radiator, However, the dual fan system is not enough to cool the oil down when you drive on the sand. The system keeps overheating therefore the 4WD system shuts down until you stop and let the system cools down for 5 or 6 minutes. It's really annoying. I'm gonna install a second fan specif for the transmission oil cooler. I noticed that once you move the car (having only the froont wheels available) and get some airflow coming from the front of the car, the system cools down quickly. The radiator fan basically does not reach the transmission oil cooler. I'll try an extra fan before trying a second oil cooler,
Are you sure it's the transmission that's overheating?
I remember years ago there were multiple reports of the 4x4 system overheating and shutting down after people had been driving on sand for a while, but it was always the rear diff (the RDM) that overheated, not the transmission.
The RDM has a clutch pack that allows variable power transfer to the rear wheels. It's this thing that causes a lot of heat build up when it's only partially engaged.
If I remember correctly, there was a TSB that updated some internal parameters in the RDM. This is circa 2015-2016 so it's been a while.
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I’m sure about it, the temperature is reaching 115ºc when I drive on the sand. Once you stops, the temperature drop’s quickly back to 75º. It’s clear that the cooler size is to small
That is excessive. Maybe your oil cooler thermostat is malfunctioning and isn't opening. I'm pretty sure there are many people who do heavy off-roading, including in sand, as well as tow heavy loads at highway speeds, and they don't report any over-temp issues like this on the transmission.
There is a thermostat that is part of the transmission cooler and it is supposed to open at 185F.
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I’ll check this sensor, maybe the problem is there. But remember, I live in UAE, we drive under 115F temperatures
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See if this Post is helpful: Transmission Temps = 190plus, anyone else?
Somewhere I thought somebody said there was a transmission cooling fan. I am not aware of one.
The radiator cooling fan speeds are controlled by the PCM? using pulse width modulation (PWM).
On my old Saab I had switches on the dash so I could turn ON either radiator fan, worked really well, but of course it did not use PWM.
Not sure if you could supply an alternate 12VDC source and use a blocking diode or not.
When I am off road I use the A/C just to keep the transmission temperatures lower. Of course it might only be 60 degrees F outside.
I have never driven my TH when the temperature is above 95 degrees F.
I think a "pusher" fan in front of the transmission cooler controlled by a switch would help.
Somewhere I thought somebody said there was a transmission cooling fan. I am not aware of one.
The radiator cooling fan speeds are controlled by the PCM? using pulse width modulation (PWM).
On my old Saab I had switches on the dash so I could turn ON either radiator fan, worked really well, but of course it did not use PWM.
Not sure if you could supply an alternate 12VDC source and use a blocking diode or not.
When I am off road I use the A/C just to keep the transmission temperatures lower. Of course it might only be 60 degrees F outside.
I have never driven my TH when the temperature is above 95 degrees F.
I think a "pusher" fan in front of the transmission cooler controlled by a switch would help.
Ahh.. I did not notice that you lived in UAE. That high ambient temperature may definitely change things.
I myself had my first ever occurrence of engine oil temperature above the 2/3 mark of the temperature gauge a few weeks ago when we had a heat waver over here and it was 110F and I was climbing a mountain, going 55-65mph.
At the same time, the transmission temp had gone up to 200F, which is just about the highest I have ever seen it.
Admittedly, this is a very different situation, but I have done the same drive many many times and have pushed the cherokee just as hard, and temps have never gotten that high.
Typically, the engine oil temp will only ever go up to 2/3 on the scale, and my transmission temp never exceeds 180 going up the same mountain, even when towing my small utility trailer.
2019 Trailhawk Elite 2.0T Olive Green Metallic Pearlcoat
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Many people here live in places like, say Phoenix, AZ, and I haven't seen this issue. I'm going with RDM overheating from possible sand driving technique. Are you dropping air pressures? That sand over there is like Glamis sand, equivalent of driving in very fine sugar...😎
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Just FYI the OP mentionned seeing 115°C for the tranny... and that is 240°F...
I remember @David_Baker , in Australia, explained in detail how his 2015 TH would overheat in the sand. He drove on the sand a lot... Maybe he'll stop by and let us know how it went for him, how he mitigated it.
I remember @David_Baker , in Australia, explained in detail how his 2015 TH would overheat in the sand. He drove on the sand a lot... Maybe he'll stop by and let us know how it went for him, how he mitigated it.
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Updating this treat..
The overheating remains when you push a bit hard on the desert... Last week I have installed a extra 10inch fan in front of the transmission cooler to push some airflow there, even if the car is parked I'll keep the fan running. I'll post a photo. On the next desert drive I'll monitor the results. Don't mind with the instalation, I have done myself in a "non invavise way" , the car is still under extended warranty coverage then I don't want to take risky of the delaer blaming my mods as a warranty void. Its easy to remove all this parts in case the car show another non related issue.
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We always deflate the tires, which is the default action prior to the drive. Yes the sand is very soft and slippery, it's a fun challenge the desert drives we do here in UAE
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Example of additional transmission cooler...
If the extra fan does not work, I'll try this one once the warranty expires
If the extra fan does not work, I'll try this one once the warranty expires
Mishimoto - MMOC-F Heavy Duty Transmission Cooler W/Electric Fan : Amazon.ae: Automotive
Mishimoto - MMOC-F Heavy Duty Transmission Cooler W/Electric Fan : Amazon.ae: Automotive
www.amazon.ae
2019 Trailhawk Elite 2.0T Olive Green Metallic Pearlcoat
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