Chronomancer

Hey guys,

I've read quite a bit on the Hot Oil and Code P0740 on JK's and wanted to see if anyone has experienced what I'm dealing with.

First off, I installed a transmission cooler off of Amazon about a year and a half ago. A week or so ago, my Jeep came up with the CEL and the P0740 code, but never really noticed anything with the shifting.

This weekend, we were headed off to camping and about 30 minutes in to the drive on the freeway, I got the Hot Oil warning - Pulled over and let it cool down. I checked my transmission fluid and the level seemed alright, but it was a little dark - Didn't smell burnt though.

So I limped home, got a new tranny filter and dropped the pan - Replaced it all and noticed after putting in 4 quarts, my gears wouldn't engage everytime - Let it warm up, checked it and it seemed a little low still. Added another quart and ran it around the block.

Came back around, and it went out of gear again. I went through all the gears again, checked the fluid and it seemed alright this time - Took it for another drive and all was well. I pulled the battery and reset the code.

Well yesterday, I took it for a drive to warm up and checked my fluid again - It seemed low still......coming up to the cold level after about 15 minutes of driving. Went through all the gears in park and then added another quart. Now it was at the Hot point again on the dip stick.

So I took it on the freeway and at the same point as last time 30 minutes in, I got the Hot Oil warning with no CEL....I checked my fluid level and it was a little over the 2nd hot mark on the dipstick looking a little high.....So now I'm at a loss, not sure what the next steps would be.

Thanks for any info!

Chronomancer

To follow up, just as I was driving about 5 miles out, I got a P0218 code, which is a hot transmission code...

Xodius

Ok a few stupid questions first. Serious...
1-you bought the cooler but did you install it? Lol I only as because a guy I talked to last week did the same f’ing thing. Bought it but didn’t install it. Lol.
2- did you install it or take it in somewhere?
2a-if you installed it make sure you have the hoses cut and spliced properly. Maybe the cooler isn’t exactly hooked up right.
3-snap a few pics of cooler and lines.
Oh and 4-did you get a factory or aftermarket cooler?

Chronomancer

Appreciate the response!

1-you bought the cooler but did you install it? Lol I only as because a guy I talked to last week did the same f’ing thing. Bought it but didn’t install it. Lol.
Haha, yep, installed it
2- did you install it or take it in somewhere?
Did it myself
2a-if you installed it make sure you have the hoses cut and spliced properly. Maybe the cooler isn’t exactly hooked up right.
I'm pretty sure I did, but I'm gonna tear it all down this weekend and re-do it to make sure
3-snap a few pics of cooler and lines.
Will do!
Oh and 4-did you get a factory or aftermarket cooler?
It's an aftermarket one I got from Oreilly's

SoK66

Are you checking the fluid with the engine running and the trans at operating temperature? If you only put five quarts in that sounds about 2-3 quarts short If I compare to my experience. Mine took nearly 8 quarts with a pan drop and filter change. I have the Mopar Performance accessory cooler.

jedg

Hard to expect it to be the cooler as the problem given the length of time you've been driving with it installed. Perhaps the pump in the transmission is failing and so it's not circulating your transmission fluid? You can check that (with some assistance) by pulling the INPUT line on your transmission cooler and then have someone start the vehicle while you point the hose into a container. It should immediately start pumping fluid. That's not much of a test as you can't be sure it's pumping at the required pressure (whatever that may be).

Maybe inspect the cooler to be sure it's not clogged? What type of cooler are you using on this?

Chronomancer

Yeah, going to check and see if it's clogged tomorrow - It's this one, but looks a little bigger:

https://www.summitracing.com/parts/h...hoCSn0QAvD_BwE

As for the low fluid, that's what I thought, just weird that it was over the high 2nd mark after it got to temp...Unless it rises like that when it gets hot from being low?

Thinking about just running it down to the local tranny shop to have them take a look at it, it shifts totally fine still it feels like.

jedg

So perhaps a silly question. Is the cooler mounted the correct direction? That type of cooler needs to have the inlet at the bottom and the outlet at the top. Some folks will mount them with inlet and outlet at the bottom. This will cause it to have air trapped at the top of the curves. I'm doubting this is the case since it went so long without problems though.