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2009 Jeep Wrangler X

2009 Jeep Wrangler X

Monday, June 20, 2011

JK Automatic Transmission Overheat Problem

Well, as you owners of JKs may well know, the 42RLE auto-tranny has some overheat issues. I decided to track the oil temp using two Glow-Shift transmission oil senders and gauges. I installed one on each oil cooler line as close to the tranny as possible. I took a test run up Highway 79 to Palomar Mountain Road out of Pala (I-15).

The outside ambient air temp was a cool 63 degrees outside.

By the time I reached the Hw79/Palomar Mt. Rd (S. Grade Rd.) split, my tranny was a whopping 288 degrees! This picture of my gauges is proof positive...the one on the left (blue) is on the transmissions oil "in" line (post-stock cooler) and is reading 252 degrees; the one on the right (red) is on the tranny oil "out" line (pre-cooler), which is reading nearly 290 degrees...ouch!

Even though that's not burning the oil, so to speak, it is seriously shortening the oil-life down to about 15k miles from what should be 100,000 miles.

This issue has been posted on and and the reasons for this are many, not the least of which is a poor design from the factory as to where the stock-transmission cooler is mounted inside the housing of the engine radiator.

I suspect that I have also compounded the problem with the Warn PowerPlant Winch sitting so high in front of the JK grill.

However, I have a solution to the problem which will be a two-pronged approach. I plan to do what most of you all do, and install an auxiliary transmission cooler in line with the stock cooler, but, as a secondary solution, I am swapping out the stock transmission oil pan and replacing it with the Rock Krawler Deep Sump oil-pan. The larger oil-pan will add about two-full quarts of oil capacity, aiding in cooling and all but eliminating oil pump starvation when inclined on those level 10 off-road hills and rocks! Here are some photos of the B&M Transmission cooler and Rock Krawler oil pan I will be installing...

Here are the web-site links for the items I will be installing in the near future:

Rock Krawler Heavy Duty Deep Sump Tranny Pan:
Note: The Tranny-Pan doubles as a skid-plate, eliminating the need for the stock skid plate which I will have to remove anyway as recommended by AEV when I install the 3.5 inch Premium Lift Kit.

P.S. I after the installations are complete, I will repeat my run up to Palomar Mt. and post my temp readings/results.


  1. You have presented each compound of this jeep very well. I must appreciate this great work. Nice job.

  2. “Congratulations TDmaster! Thank you so much for taking the time to share this exciting information.”

    read more

  3. Have the same problem, not solved with the cooler!

  4. I am thinking of getting a class action going against Chrysler for this my tranny just went in my jk 2011 and they wont cover under warranty , even tho I have brought it in for service for that issue amongst constant complaints of tranny overheating , please contact me