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Discussion Starter #1
I'll try to keep it short and sweet, but here's the situation. I've taken my new (to me) '08 JK 2dr auto on several trail rides since I've got it a few months ago. The last two times I've headed up into the hills, I end up with a random squeak that appears mostly at idle (any shifter position) give or take a few hundred RPM. If you bring the RPM's up past 2000-3000, the sound generally goes away, for 15-30 seconds, then returns slowly. Yes, I've read plenty about the need for an aftermarket trans fluid cooler, but mine appears to already have one mounted in front of the lower part of the radiator.

My theory is that it has something to do with the transmission heating up. I can drive around town with no noise. Even on the trail, it takes awhile before it begins. I usually do rocky and steep areas in low range, since it seems like it would mean less slipping for the transmission. There are no other noticeable symptoms (warning light, hard shifts, delayed shifts, etc) besides the noise. It sounds a lot like an idler or tentioner pulley when they're nearing the end of their lives, although the sound is less consistent: it will squeak, miss a beat or two, squeak squeak, miss a beat, etc.

I found a few sites that help diagnose different noises and issues reported with auto transmissions. From everything I could gather, the noise pointed to a failing fluid pump, or restricted flow to the pump by way of a clogged filter. That being the cheapest and easiest route, I dropped the pan, changed the filter and refilled. Noise came back the next trip.

I don't know what to do. It already has some sort of trans cooler - not sure if it was installed as an accessory or what. Would a B&M cool better than whatever Mopar (or whatever) cooler is currently in place? Help/suggestions /etc would be much appreciated. I'm worried about the coming summer heat. If I can't go wheeling at 70 deg without it heating up, it'll be useless in July and Aug. :/
 

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Did your Jeep have the recall performed to add the hot transmission fluid indicator? If it did, there would be a page added to the owner's manual. What you describe (I think) is the transmission cooler in the A/C condenser. The B&M would be added as a supplement to the OE cooler; in line after the factory one. I just did one in my Jeep this weekend because of the hot Florida summers. FWIW, my Jeep did not have the recall done.

The cooler will run you like $60 or so depending on where you buy it. It would be well worth the cost versus having to replace the tranny.
 

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Discussion Starter #3
Ah, so what I saw is probably the condenser rather than a tranny cooler. That makes a ton of sense! B&M cooler it is! I'm really wanting to take care of this before it becomes an expensive problem.

Thank you for the fast response! I hope you're right, as that was my next plan of attack anyway.
 

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Ah, so what I saw is probably the condenser rather than a tranny cooler. That makes a ton of sense! B&M cooler it is! I'm really wanting to take care of this before it becomes an expensive problem.

Thank you for the fast response! I hope you're right, as that was my next plan of attack anyway.
Just to be 100% clear... I'm no expert on this stuff, but it seems I've read on here that the OE transmission cooler is in the lower part of the condenser. It seems it doesn't work exceptionally well, hence the recall.

I also have an '08, so I decided to limit my risk and add the B&M. It was a fairly easy install. If you need some help, or some pictures, just lemme know.
 

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Discussion Starter #5
Just to be 100% clear... I'm no expert on this stuff, but it seems I've read on here that the OE transmission cooler is in the lower part of the condenser. It seems it doesn't work exceptionally well, hence the recall.

I also have an '08, so I decided to limit my risk and add the B&M. It was a fairly easy install. If you need some help, or some pictures, just lemme know.
I've been looking at them and it appears that they come with hose and fittings. Did the kit have everything you needed for install or did you require any additional hose/fittings /etc?
 

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I've been looking at them and it appears that they come with hose and fittings. Did the kit have everything you needed for install or did you require any additional hose/fittings /etc?
It comes with everything if you want to tap straight into the lines where they connect to the condenser. I did not. I cut the rubber hose on the return line going to the transmission, so I bought (2) barbed couplers which ran me about $4 and I also bought some extra rubber hose to be sure I had enough to run the lines where I wanted to.

There are some write-ups on here and if you Google it, you'll find more. B&M even has an installation video, IIRC.
 

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Discussion Starter #7
Alright, I installed a B&M 70268 cooler tonight. Now to hope and pray that nothing leaks and it brings down the temps enough to get rid of my noise! :whistling:
 

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Discussion Starter #9
I mounted it sideways. After reading several threads on the subject, the consensus seemed to be that sideways works well. I'm going to go tow a little fishing boat for 2 hours tomorrow, so we'll see how the cooler does. Unfortunately I don't have "before" temps to compare to, but we'll just assume it was too high.
 

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Discussion Starter #10
*** Update ***

As I posted a few days ago, I installed a trans fluid cooler hoping that it would prevent overheating as well as the noise I believed was caused by the high temps. After pulling a small (12' fishing boat, <1000 lbs) trailer across town for less than 30 min, I noticed the sound again. :pullinghair:

Again, it resembles the sound of an idler pulley bearing that is going bad. However, the sound is most clearly heard when you get under the vehicle and put an ear close to the transmission. Its got me afraid to take the Jeep up into the hills, as it would be incredibly difficult to tow it out.

What I find weird is that I don't see any other similar problems noted anywhere online. The traditional symptoms of an overheated JK trans has to do with sticking in gears (usually 2nd) or losing power altogether... I'm tempted to take it to a transmission shop, but I know they'll just say they can't replicate the sound and charge me a few hundred $ for diagnostics. It only seems to occur when the Jeep is under additional load for an extended period of time, and I don't think a mechanic will go tow a trailer around.

Thoughts, ideas, suggestions?
 

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Discussion Starter #11
I'll take the cumulative silence to mean that nobody else has encountered something like this. Now I'm wishing I would have taken the bait at the dealership for that pricey extended warranty...
 

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I would redo all the pulley's and serpentine belt. I don't know about the 3.8 but the 3.7's start squeaking when the water pump is going bad.
 

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Discussion Starter #13
I would redo all the pulley's and serpentine belt. I don't know about the 3.8 but the 3.7's start squeaking when the water pump is going bad.
I really don't believe it to be one of the pulleys, as the sound is much louder when under the vehicle than when listening in the engine compartment with the hood up. However, I will probably hit each pulley with some PB to see if the sound stops after I've heated it up enough to conjure the noise again.
 
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