What is the normal operating transmission temperature? And what is the high temperature that could cause damage?
2005 4.0
4 speed Automatic 42RLE
2005 4.0
4 speed Automatic 42RLE
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The Factory Service Manual says 240° is overheating.
I think the normal operating temps should stay around 120-160°, but in my temp gauge & IR thermometer have shown it runs around 180-200° in stop and go traffic on a 90°+ summer day. in the mountains, climbing switchbacks in 1st and 2nd @ 15-30mph, it runs very hot, around 200-240°.
the radiator runs at 210°F, and the tranny fluid is running through that. Both "hot" and "cool" trans lines pass less than 1/2" away from two catalyitic converters with a heat shield radiating 600-700°F. I tend to think the 42RLE runs very hot in the TJ.
It's programmed to lockup whenever possible, in an attempt to reduce the temps. Also note every other 42RLE equipped Jeep came with a big ass auxiliary tranny cooler (thinking of the Liberty specifically).
One thing that will drive transmission temps up is running larger diameter tires than stock, and not re- gearing. The 42RLE has a crazy tall overdrive, and requires a surprisingly short axle gear ratio to keep from overworking the transmission.
I installed a gauge today. @ 65mph with 33x10.5 tires and an empty Uhaul motorcycle trailer, my tran temp fluctuates from 178 to 191. KY hills.
The Derale is on my spring list. Thanks for all the info. Love this forum.
With those tires, you really need 4.88-5.13 gears.I installed a gauge today. @ 65mph with 33x10.5 tires and an empty Uhaul motorcycle trailer, my tran temp fluctuates from 178 to 191. KY hills.
The Derale is on my spring list. Thanks for all the info. Love this forum.
With those tires, you really need 4.88-5.13 gears.