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Discussion Starter #1
I know quite a few people have done this already, but just thought I'd share what I did.

Although after installing a transmission temp gauge the temperatures looked okay, I was still concerned about the temp when off-road and when the tranny is working hard. As I'm just about out of warranty, I decided to add a transmission cooler.

I went with a B&M 70268, which comes with pretty much everything needed to install it. I retained the factory cooler and added this one in line with it on the return line (the upper transmission cooling line), and spliced into it at the rubber section below the main radiator. In this instance using a couple of 3/8" brass barb splices is better than using the parts provided with the cooler.

I went with the B&M as it is a plate design rather than just a tube with cooling fins, it offers a low pressure drop, and when cold, bypasses some fluid passed the stacked core.

Installation was straight forward and the instructions are pretty clear and helpful. It seemed to fit better sideways, B&M recommend that either the inlet/outlet are facing up or sideways, and that when facing down the cooler will be the least efficient.

I connected it to return line (upper line), connecting the inlet on the cooler (lower connection) to the line coming from the factory cooler, and the outlet (upper connection) to the line going towards the transmission.

When mounting the cooler, be aware of the hood latch and make sure it does not contact the cooler before finalizing the mounting position.

With the new transmission temp gauge installed I could instantly see a drop in temps.

On the highway with the transmission locked I am running at about 120°F, stop and go driving driving is around 130°F, this is a 20-30°F drop in temperature. It should be noted that this is measured from the return line, so this is cooled fluid going back in to the pan. This gives a good indication of pan temp and also shows changes in temp quicker.

I'll be interested to see what the temps are when off-road or working harder in hilly country.



 

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Digging up an old thread.

Has anyone installed the tranny cooler inside the engine bay behind the E-fan? It should get plenty of air and there is plenty of room. Just looking at options.
 

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Discussion Starter #4
You'd have to make up some kind of bracket. I'm guessing it would be less efficient also, as the ambient temp in the engine bay is pretty high, as is the air that's just been heated up by the radiator.
 

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I'm not trying to hijack this thread; but it seemed to be a good place to start. Has anyone tried a cooler with it's own fan assembly? Does it fit in between AC condenser and the grille? Wouldn't this be the best for crawling at high rpm and low speed?
 

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Discussion Starter #6
I haven't found any issue using a non fan assisted cooler, and I wheel in some hot conditions. I personally don't think it's needed.
 

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new reply to older post

I installed this same cooler, same line (upper). I had a tranny warranty issue, so I took it in, got it more or less looked after. The service writer told me I had it hooked up to the feed line and was cooling before the fluid hit the rad. He gave me the mopar instruction printout for the 2010 JK. It specifies that the lower coolant line is the return to tranny and that the lower coolant line is the one I need to splice into.
Anyone care to comment?
 

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There's one way to find out for sure. Disconnect one of the hoses and have somebody start it up for a second (may want a bucket and add some hose extensions into it). You'll know by which way the fluid comes out whether if you have it hooked up right or not. But since the factory cooler is not internal to the radiator, it really doesn't make too much difference either way, IMO.
 

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Discussion Starter #9
There's one way to find out for sure. Disconnect one of the hoses and have somebody start it up for a second (may want a bucket and add some hose extensions into it). You'll know by which way the fluid comes out whether if you have it hooked up right or not.
I thought I did that, but it's been a while so can't say for sure.

But since the factory cooler is not internal to the radiator, it really doesn't make too much difference either way, IMO.
X2 Either way you are cooling just before the factory trans cooler or just after.

I could not find a diagram in the FSM which stated which line was which. I found the schematics showing the main components and fluid flow for each gear, which does show the output to the cooler near the top, but I don't believe the schematic is laid out the same as where the components actually are.
 

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It may not matter but the instructions for my Hayden say to install it after the factory cooler so I'll try:D I'll find out soon (hopefully tonight) and report back for the '08. I've got the cooler mounted and finally got the right hose, the one with the kit was 3/8 and the extra one I got originally was 5/16.
 

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The lower line is the return line, but that is not the line to splice a cooler into. Even the factory cooler's INLET comes from the transmission's OUTLET, which is the one on top.
 

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Discussion Starter #12
Even the factory cooler's INLET comes from the transmission's OUTLET, which is the one on top.
It would have to, but the traditional school of thought says that you want to run an additional cooler on the return line to the transmission. This is also what B&M recommend.

As already mentioned above, I don't think it matters that much if you cool just before the factory cooler or just after.

Of course if I got the lines mixed up, it's most probably connected how you are suggesting anyway :D
 

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This is a great write up and a mod I intend to do real soon. Thanks :D
 

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Thanks to all. Logic (and B&M) tell me I had it right the first time, but my warranty provider feels otherwise. Both ways worked.... No more HOTOIL stupidity!
 

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Can someone tell me if this is right? Or are my auxillary lines mixed up? I am a little confused where the new lines connect in.

 

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Can someone tell me if this is right? Or are my auxillary lines mixed up? I am a little confused where the new lines connect in.

easy way to check... after your JK has cooled off... i.e. tranny, lines, cooler... start it up and find out which line warms up first... that one would be going towards the cooler... you would want the other... the return line.
 

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It's not right if it doesn't include the factory cooler.
Yeah I know it needs to include the factory cooler. I didn't draw it on that sketch, I was only asking of where the aux. lines go after the cut is made to the oem line.
 

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Yeah I know it needs to include the factory cooler. I didn't draw it on that sketch, I was only asking of where the aux. lines go after the cut is made to the oem line.
I gotchya....and I wasn't tryin to be smart. I was just sayin.....I know the stealer will have a leg to stand on in a warranty claim if the factory cooler is bypassed. As long as it's in the system, and the auxillary cooler was done right, they really cannot say much.
 

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easy way to check... after your JK has cooled off... i.e. tranny, lines, cooler... start it up and find out which line warms up first... that one would be going towards the cooler... you would want the other... the return line.
Yes that's right on my '08, I used this method.:D
 
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