Trans coolers

[CrazyCooter]

If you want to keep all temps down, coolant, oil and trans install a RPM Extreme JL fan controller.
You will be amazed at how well it works keeping all temps down.
I have been running one for 3 years now and my coolant and oil temps are down by 25 to 30 degrees.
Your jeep has a transmission heater so you will always see temps about the same as the coolant.


A Mopar transmission heater (also known as a transmission warmer or heat exchanger) works as an oil-to-water thermal regulator. It circulates hot engine coolant through a series of passages directly adjacent to the transmission fluid to maintain optimal fluid temperature and viscosity. [1, 2, 3, 4, 5]

How It Operates

• Cold Starts & Warm-Up: When the engine is started in cold weather, the transmission fluid is thick, which causes sluggish shifting and increased wear. The heater uses the rapidly heating engine coolant to quickly warm the transmission fluid to its ideal operating temperature. [1, 2, 3, 4, 5]
• Thermal Bypass Valve (TBV): A built-in thermostat controls the flow. It directs transmission fluid through the heater until it reaches roughly 180°F (82°C). Once the fluid reaches this threshold, the TBV routes the fluid to the external transmission cooler to prevent overheating. [1, 2]
• Cooling Mode: If the transmission works hard and exceeds engine coolant temperatures, the heat exchanger works in reverse, allowing the cooler engine coolant to absorb excess heat from the transmission fluid to prevent it from overheating. [1, 2]

If you are experiencing issues with your transmission heater—such as a coolant leak, a check engine light, or harsh shifting in the cold—provide the model and year of your vehicle to help determine if the thermostat or heat exchanger needs to be

https://store.mopar.com/oem-parts/m...0PdLuwF91hQpZ3xquKYmrhPzDGXe8hj4aAgm5EALw_wcB

http://www.rpmextreme.com/Product/311/Jeep-JL-JT-PWM-FAN-CONTROLLER-.aspx

It appears as if RPM's controller still doesn't support 3.0 Diesel applications?

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[caryt]

Just use a Tazer ...

 

[willys 41]

How difficult is that to install, I am a busy wiring guy

I am assuming you mean the RPM fan controller.
Very easy. Just take your time and a lot of light to identify the correct wire colors.
I my case with old eyes a magnifying glass helps.

 

[willys 41]

It appears as if RPM's controller still doesn't support 3.0 Diesel applications?

Maybe not yet. Put he may be working on it. I was the first one he maid one for the jeep JL.

 

[willys 41]

Just use a Tazer ...

The tazer is not the same.
RPM Controller. I have never hit the 212°F / 100°C = 75% fan speed. The controller works that well.
Example Fan Speeds by Temperature:

• 195°F / 90°C = 15%
• 199°F / 93°C = 30%
• 205°F / 96°C = 50%
• 212°F / 100°C = 75%
• 218°F / 103°C = 100%

 

[caryt]

Never said its the same, I control the Tazer plus does many other things. I live at 5kft and have 6+* roads everywhere and we get in the high 90's all summer. Even with the fan on high oil temps get over 230++
Water temps never been a issue its oil temps.
$325 for something that does 1 thing vs a Tazer mini for under $280..such a deal.

 

[willys 41]

Never said its the same, I control the Tazer plus does many other things. I live at 5kft and have 6+* roads everywhere and we get in the high 90's all summer. Even with the fan on high oil temps get over 230++
Water temps never been a issue its oil temps.
$325 for something that does 1 thing vs a Tazer mini for under $280..such a deal.

I have both. Tazer and RPM controller on both my wranglers. Its a win win for me.

 

[Gladiator Brad 704]

What is your target temperature for your transmission? Does the transmission fluid circulate in the radiator to assist in warming? Can this warmer function be bypassed?

 

[willys 41]

The normal operating transmission temperature for a 2020 Jeep Wrangler ranges between 175°F and 225°F. During normal driving conditions, your temperature will typically hover between 180°F and 210°F.

Temperature Ranges at a Glance

• Ideal: 175°F to 200°F
• Normal Operating: 180°F to 225°F
• Heavy Load/Towing: 215°F to 235°F is acceptable, though it should be monitored closely.
• Warning Zone: Above 230°F to 240°F
• Danger Zone: Above 240°F to 250°F (Fluid begins to break down, varnish forms,

 

[@californiajeeping]

I have the ecodiesel and 40s with the CSF and unfortunately the heater thingy on the trans keeps trans temps at 200-205 unless its cold out.

You can see it work when it goes from 150-160 to 200 suddenly and holds. Basically without bypassing the factory heater valve you can only do so much.

I get random spikes with no load up to 210-220. I believe its the heater messing up.

 

[Planerdude]

I cant say I've even seen mine that high.......seems like 205-208 sustained while towing heavy at 100°ish ambient, climbing to maybe 217° on some hard pulls, but drops right back down to 205° afterwards.

Now if a trans cooler could reduce heat load from the coolant or transfer heat out.......I'd be in! New low temp thermostats or thermostat deletes are pretty common for the Rams and Grand Cherokees, but I haven't seen anything offered for a JL/JT? May be interchangeable, but wouldn't they be marketed as such if it was?

The 2022 and newer models deleted the thermostat from the trans heater assembly. You can swap them out directly.

 

[willys 41]

Not sure about that. According to mopar one fits all.

Mopar Transmission Heater - Mopar (68485460AB)

2016-2026 Mopar - 68485460ab

Engines: 2.0L I4 DOHC DI Turbo Engine w/ ESS. 2.0L I4 DOHC DI TURBO ETORQUE ENGINE. 3.0L V6 TURBO DIESEL ENGINE W/ESS G3. 3.6L V6 24V VVT Engine Upg I w/ESS. 3.6L V6 24V VVT eTorque Engine Upg I. Transmissions: 8-Spd Auto 850RE Trans (Make). 8-Spd Auto 8HP75 Trans (Buy-Germany).

 

[caryt]

From what I have seen they went to the new cooler in min 2001 so since mine was made 10/2021 I checked and I do have the newer cooler. So based on this I'll get some additional cooling from a larger cooler.

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