Overheating Transmission

[odoyle]

I was finally able to get my LJ out of the garage and up to the mountains this weekend, but as soon as I got to the trailhead I discovered I had ATF spewing from somewhere on the upper passenger side of the tranny. I wasn't quite sure at the time where it was all coming from (it seemed like a lot of fluid), but I could visibly see some of it coming out of the vent tube. Upon further inspection, after trailering it back home, I wasn't able to see any other areas that may have been leaking, which leads me to believe it was all coming from the tranny vent tube and just dripping all over the place.

I have had the LJ for only a few months and have had it on the highway a handful times without any overheating issues. This trip was definitely the most demanding drive so far, about 60 miles with 5,000 ft of elevation gain. The check engine light has been on previously for other issues, but I ran my scanner and now its showing P0700 and P0845 transmission related codes. I am assuming that my issue is the 42rle is overheating, but what should my next steps be?

The transmission is currently cooled by a basic auxiliary cooler that is mounted on the front of the radiator and it bypasses the stock radiator cooler. I am wondering if I need to get a beefier cooler or if there are other adjustments that need to be made. Any input or thoughts are appreciated!

 

[-T.]

I've seen them burp fluid like that when they have been overfilled. Any reason why the factory cooler was completely bypassed, rather than run in line with the aftermarket? Seems counterintuitive. Maybe the auxiliary cooler isn't cooling enough? I don't know that those are designed to be the only cooler for the trans, or just to provide additional cooling.

 

[rouxbicon]

I've seen them burp fluid like that when they have been overfilled. Any reason why the factory cooler was completely bypassed, rather than run in line with the aftermarket? Seems counterintuitive. Maybe the auxiliary cooler isn't cooling enough? I don't know that those are designed to be the only cooler for the trans, or just to provide additional cooling.

Exactly...

In most cases the auxiliary cooler is just that...an auxiliary or extra cooler, not intended to replace the factory in-radiator cooler. I would definitely run it through the radiator cooler, and then also the auxiliary cooler if you feel you need the extra cooling.

 

[S.McArthur]

bypasses the stock radiator cooler

Read here about bypassing the transmission cooler, I'd type, but it's best to go here.
https://wranglertjforum.com/threads/auxiliary-transmission-coolers.10489/

 

[odoyle]

Thanks for the feedback. The current cooler setup was done by the previous owner so I am not sure what there reasoning was, but I am going to go ahead and route back through the radiator and then through the aux cooler. I am also going to add a temp gauge so that I can monitor it. If that doesn't work then I will probably upgrade the cooler to a Derale or at least something with a fan.

 

[pagrey]

Save your money, don't buy another cooler. You'll probably need to rebuild your transmission. A cooler won't fix broke. An overheating 42RLE doesn't throw codes, the factory didn't think it was a big deal. Opinions vary but I trust the people that built the machine.

A temp gauge is probably a good idea.

 

[toximus]

Save your money, don't buy another cooler. You'll probably need to rebuild your transmission. A cooler won't fix broke. An overheating 42RLE doesn't throw codes, the factory didn't think it was a big deal. Opinions vary but I trust the people that built the machine.

A temp gauge is probably a good idea.

Regardless of who you trust, there is an extremely high correlation between overheating the 42RLE and it's lifespan.