42RLE auxiliary cooler and temp gauge

BigDan

TJ Enthusiast
Original poster
Supporting Member
Joined
Aug 21, 2021
Messages
139
Location
St-Jean Baptiste , Quebec.
2005 LJ automatic ( 42rle)
I’d like to install an auxiliary cooler and temperature gauge
Any advices or how to ?
Thanks ,
Dan
 
Setrab
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I wont install the sensor in the pan
The most effective way is on the exit cooler line going to the rad

It is not right way of measuring the temperature. This will tell you temperatures that are way higher that how the transmission temperature is defined. Also, the output fluid temperature fluctuates a lot, especially during the acceleration

The transmission itself does not measure that way. The transmission temperature sensor is located inside the range selector column inside the valve body. It correlates very well with with the pan temperature, unless you are driving really fast in the cold weather.
 
I've installed sensor in pan and installed the setrab mentioned above. Saw roughly a 40 - 50 degree reduction during hot times pulling up a hill on the highway.
 
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It is not right way of measuring the temperature. This will tell you temperatures that are way higher that how the transmission temperature is defined. Also, the output fluid temperature fluctuates a lot, especially during the acceleration

The transmission itself does not measure that way. The transmission temperature sensor is located inside the range selector column inside the valve body. It correlates very well with with the pan temperature, unless you are driving really fast in the cold weather.
X2.
 
From the moment that I installed the Derale electric cooler, my transmission never visited above 185F. Like never.
Derale electric cooler comes with 7 inch electric fan, the moment it kicks in, it immediately drops the temperature to ~180F area.
Reason why electric is better, is because it does not impact the airflow to the radiator, and works perfectly fine in very low speeds, like when you crawl.
 
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I did the Derale cooler, made a small cage for it and put the temp gauge on my roll bar pillar. I had Blaine hook up the sensor port and have had no issues.

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Any advices or how to ?


The TJ specific Derale cooler is good for a bolt in solution.
On my LJ, I eventually moved it farther back, under the tub.
So, I could have bought a cheaper one not in a kit.

Here's my gauge.
guage.webp
 
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Bought a drain plug kit from dorman p/n 65128
Retap regular plug thread to 1/8 pipe thread , suits the sensor perfectly ( depth wise)
Took your advices on this one 👍
Thanks ,
Dan
 
Last edited:
From the moment that I installed the Derale electric cooler, my transmission never visited above 185F. Like never.
Derale electric cooler comes with 7 inch electric fan, the moment it kicks in, it immediately drops the temperature to ~180F area.
Reason why electric is better, is because it does not impact the airflow to the radiator, and works perfectly fine in very low speeds, like when you crawl.

have been doing some trails last weekend. Not extremely technical ones, more like light ones, especially taking into account that the land is completely dry.
I got my transmission to 187F, but never went beyond.