Improving the cooling on our TJs
- Thread starter TexasTJ2004
- Start date
No creeping issues at these ambient temps in idle. Summertime is a very different story when ambient temps are 110*-118* (especially with the AC on).
I've idled a bunch since October in AZ, NV, and UT which included brief offroading adventures to Moab, Sand Hollow, southern NV, and southern AZ in a mix of 4hi and 4low.
FWIW, I found that trailing in 4hi caused my transmission temps to reach and go past 200* with the Derale cooler... I avoided this by switching into 4low to cool it back down to 165*-175*. My ECTs barely budged under load or in idle, which was impressive and comforting.
Edit: this is with a setrab cooler and power steering cooler in the grill.
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Just my luck , I was looking for temps. in K , ( kelvin ) .
You may know this, but in case others don’t, running a trail slowly in high - meaning lower rpm’s at the crank - does not allow the torque converter to lock up as much, and the resulting slipping of the converter is what creates the additional heat.
I did not know the reasoning thanks for sharing man.
My wallet isn’t ready for a rubicrawler & atlas 2.0 combo that Blaine brought to my attention. But, maybe adding a rubicrawler to get the 2.72:1 gearing option would be helpful enough to drop transmissions temps in 4hi situations. I’ll need to confirm if the rubicrawler for the TJ 242 is the same that works with the Atlas.
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my brand new Mopar radiator waiting to be installed.
It has different transmission cooler connector, so I bought these ones to adapt the radiator to transmission cooler lines.
DEWHEL 2pcs Brass 397 Transmission Line Fitting Kit Fits for GM 1996 and Later Snap-in Style Lines https://www.amazon.com/dp/B0BR9L6VV7/?tag=wranglerorg-20
It has different transmission cooler connector, so I bought these ones to adapt the radiator to transmission cooler lines.
DEWHEL 2pcs Brass 397 Transmission Line Fitting Kit Fits for GM 1996 and Later Snap-in Style Lines https://www.amazon.com/dp/B0BR9L6VV7/?tag=wranglerorg-20
It is for 2005/2006 auto, which has slightly different transmission cooler lines.
Trailing in 4HI creates much more load on the transmission. Not healthy for it.
On my last trip to Big Bend, I put into 4L every time when i moved off the pavement into the trail. I have manual hubs in the front (conversion kit), so I kept the hubs unlocked in 4L, and locked them only when 4x4 was really needed (basically it is a 2L mode in some way). The trail was dry, so I had to lock the hubs only one time when i did the step on the Black Gap trail itself.
The transmission temperature stayed relatively low, never reaching beyond 180F, so the derale cooler did not have to kick in.
Well, I guess it’s good that I basically never used 4hi until this October.
I prefer to keep my hubs locked when I’m off-roading, but they are great to have on the highway or in case I break a joint up front.
I don't like the 4:1 ratio on trails that I can go faster on. Might end up going the Rubicrawler route to gain the 2.72:1 gearing option. (would love to add an atlas later/someday)
My Derale fan runs most of the time. My trans temps are usually 160*–180* in 4low.
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I replaced the oil pan with pan with drain plug where I installed the temp sensor and routed it to a gauge in the cabin.
I don't believe the trans temp is reported by the PCM for the 99-04.
IIRC, the 05/06 PCM reports the trans temp since the TCM is integrated. That integration is also why the 05/06 PCMs have a higher failure-rate due to excessive heat (which the WranglerFix PCM resolved for me).
Edit: In case you are interested, Blaine brazed a bung into this Dorman Pan (with drain bolt) that I purchased. I had that done and connected an Autometer (z-series) gauge to it before I owned the obd2 gauge. It worked great.
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Temp sensor is a part of every single 42RLE, so any 2003 to 2011 automatic wranglers have it.
It is located inside the range selector in the bottom of the valve body. It is a thermistor voltage on which changes with the change of it’s temperature and the transmission control reads the voltage and translates it to temperature reading (it uses predefined voltage to temperature mapping table, you can find the spec and the mapping inside 42RLE repair guide).
In 2003/2004 the TCM is not a part of PCM and is a separate module unrelated to PCM, so OBD from PCM cannot present the transmission temperature. In 2005 to 2011 the transmission controller is integrated into PCM so OBD reader can see the exposed data for transmission.
I bought the same oil pan (Dorman 265-818 Automatic... https://www.amazon.com/dp/B00Z7O4OVA/?tag=wranglerorg-20).
Just replaced the drain plug with transmission temperature sensor. Pretty simple.
For my 2004 that was the only option to get the temperature.
I did that method out of necessity so I could watch my temps driving my rig to Blaines before he added a bung. I don't recommend doing that to others because the sensor sticks out like a lollipop and can be snapped off (and cause a catastrophic failure). Also, placing the sensor there doesn't allow the Savvy skid plate to be installed.
You want the sensor to be protected like it is where Blaine places them.
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