Tranny cooler woes

Boostwerks.com said:
How many miles are on the trans? Have you noticed any slippage? Even with some VB pressure mods and shift kit we still run roughly 150Deg with normal driving. Stop and go can get it up to 180-190, but hasn't passed 200. I have a mid size hayden cooler as well.

Before ruling out the trans, I would remove both cooler lines @ the trans and check for blockage. Also the fluid level is critical so this may have something to do with it. I would drain some out until the level is correct when fully warm, running, and in neutral.

Also be extremely careful with leaking atf! It is very flammable after all.

Hang in there!
Click to expand...

200k and no slippage, TC is locking up as it should and i get RPM and ground speed rising together on acceleration as it should.

Good idea on popping the cooler lines loose. I know the tranny outlet is unclogged, I blew fluid everywhere doing a poor mans flush but the rear inlet line could be clogged.

Now I need to hunt down some new O-rings for those fittings on the tranny.
 
Update!

I'm on borrowed time but this tranny is still going! I have cycled it over 300* multiple times and it still shifts fine. The fluid is still a clearish red and does not smell burnt. I know for sure the gauge is reading correctly.

I have one more trail run and I'm pulling the tranny out(fingers crossed)
 
Okay, so many months later I finally got around to swapping out the transmission. Guess what, it still runs hot!

I swapped in a low mileage AW4 and torque converter from a 96 XJ that I owned and was totaled. This tranny always ran perfect and cool(I had a B&M tranny gauge on this Jeep as well) It never got over 150.

So on this XJ, also a 96 its running really hot, 200-300. What is going on? I have eliminated the gauge being the issue. I have 2, yes "2" tranny coolers on this trail rig and it still runs hot. I have blown out the lines, there are no kinks, only two right angles in the cooler lines.
 
xjtrailrider said:
Okay, so many months later I finally got around to swapping out the transmission. Guess what, it still runs hot!

I swapped in a low mileage AW4 and torque converter from a 96 XJ that I owned and was totaled. This tranny always ran perfect and cool(I had a B&M tranny gauge on this Jeep as well) It never got over 150.

So on this XJ, also a 96 its running really hot, 200-300. What is going on? I have eliminated the gauge being the issue. I have 2, yes "2" tranny coolers on this trail rig and it still runs hot. I have blown out the lines, there are no kinks, only two right angles in the cooler lines.
Click to expand...

Where are the tranny coolers located? Are they being warmed by a near by heat source? Are they in a spot that gets crappy air flow?
Try rigging a fan on a switch to the cooler directly before the tranny and see if that makes a difference. Is the a/c condenser clogged and not letting air flow thru It?
 
bluejeepkid said:
Where are the tranny coolers located? Are they being warmed by a near by heat source? Are they in a spot that gets crappy air flow?
Try rigging a fan on a switch to the cooler directly before the tranny and see if that makes a difference. Is the a/c condenser clogged and not letting air flow thru It?
Click to expand...

I have a Derale 2-pass 26" cooler in front of the front cross member and behind the winch bumper and then a small Hayden with a 6" fan just behind the front cross member and pulling air across both coolers using one of the large holes in the cross member.

My next step is to re-plumb the coolers and maybe even eliminate the Derale cooler. It might be that there is just too much for the pump to push the fluid through fast enough.
 
Could be.
Also,,maybe the hole in the front crossmember just isn't big enough to let enough air through. Or, maybe that plus the winch blocking air flow as well might togethor cause a problem
 
Demonoid369 said:
If two tranny's are over heating one one jeep, I'd start looking else where, you geared properly? TC locking up? Etc...
Click to expand...

4.88's and 35's, TC is locking up, no slippage, shifts the same both trannys. This tranny is a known good and i'm on my third temp gauge/sender combo. I have used a infra-red gun and get lower temps on the lines/cooler but infra red is not always accurate.

I'm a good problem solver but this one has me perplexed.

And to beat all, my old tranny is now trashed due to a snapped selector shaft from trying to get the rusted nut off the lever.
 
Well my thought process is that if the first tranny was over heating in one jeep, then add another non over heating tranny to same jeep and now that tranny is over heating, something wrong with your jeep, exhaust leak? Have you checked that nothing is blocked in the coolers? Is it a 00'-01'? Maybe precats are some how heating it?
 
Demonoid369 said:
Well my thought process is that if the first tranny was over heating in one jeep, then add another non over heating tranny to same jeep and now that tranny is over heating, something wrong with your jeep, exhaust leak? Have you checked that nothing is blocked in the coolers? Is it a 00'-01'? Maybe precats are some how heating it?
Click to expand...

Its a 96. I blew out the lines while the tranny was out and got solid air flow through the lines and coolers. No exhaust leaks(passes the VA state safety inspection) and no precats.
 
MoparManiac said:
Move the cooler in front of the mechanical fan.

You're not getting any airflow being behind your winch bumper.
Click to expand...

When I had the cooler in front I had engine overheating issues. That is why i went to the Derale cooler. The cooler is mounted so that air flows over it through the gap between the bumper and the front cross member. Then I added the fan.
 
xjtrailrider said:
I have a Derale 2-pass 26" cooler in front of the front cross member and behind the winch bumper and then a small Hayden with a 6" fan just behind the front cross member and pulling air across both coolers using one of the large holes in the cross member.

My next step is to re-plumb the coolers and maybe even eliminate the Derale cooler. It might be that there is just too much for the pump to push the fluid through fast enough.
Click to expand...

That Derale Heat Sink is not going to cut it. Get rid of it. What is the other cooler you have? You need a good purpose built transmission cooler with matching fan. What is the temperature at highway speeds?

My XJ have a Summit 4 pass 20 inch tube and fin and the temperature sometimes get up to 230* in stop and go traffic in the summer. I have added a 300 CFM Derale fan that helps but not enough for me to be comfortable with. I will be changing it soon for something better soon.

I do not have a winch or winch bumper but the oil cooler is also behind the front cross member. It run between 150 and 160 after 10 minutes on the highway.
 
techno1154 said:
That Derale Heat Sink is not going to cut it. Get rid of it. What is the other cooler you have? You need a good purpose built transmission cooler with matching fan. What is the temperature at highway speeds?

My XJ have a Summit 4 pass 20 inch tube and fin and the temperature sometimes get up to 230* in stop and go traffic in the summer. I have added a 300 CFM Derale fan that helps but not enough for me to be comfortable with. I will be changing it soon for something better soon.

I do not have a winch or winch bumper but the oil cooler is also behind the front cross member. It run between 150 and 160 after 10 minutes on the highway.
Click to expand...

My other cooler is a Hayden 4-pass with a 6" 300cfm fan pulling through it. I could mount that cooler somewhere else and delete the derale, I just don't know where to mount it.
 
Are you grounding out the temp sender properly? I always used to get high readings, I added a small section of wire from the T junction I used on the cooler line to the frame rails to provided a good ground. Low and behold, my gauge read normal after that.
 
foxwar71 said:
Are you grounding out the temp sender properly? I always used to get high readings, I added a small section of wire from the T junction I used on the cooler line to the frame rails to provided a good ground. Low and behold, my gauge read normal after that.
Click to expand...

Yes, separate grounds to both senders. I have a sender on the outlet and inlet of the coolers and ran through a switch to the gauge, I can read one or the other.
 
My opinion is that either your gauges don't indicate correct values (and ir thermometer reading on the tranny pan should give you the closest real readings), either the cooler you use is not getting enough ventilation. I would really get a big tranny cooler, mount it in front of condenser so it gets the maximum air flow. You may need to spend 100+ for a new one, but considering the hassle you've been through, I think it's worth.

You could go to an auto parts store, buy an ir thermometer, use it to confirm the temperature and then return it back (since it seems you're not sure about the accuracy of the one you used).

I attached a pic with how I set up my cooler, and I had never seen temps greater than 170, but I also run 31s with 3.55. I don't think though that tire size is a cause since it seems you have the proper gearing, if anything it should be an issue with my gearing generating more heat, lol.

pu8aje8y.jpg


This is the pic with a new one, same as the one I have, just as an idea regarding the size.

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A cooler like this is slim enough to fit between the grill and condenser, making some brackets is very easy also. I think I paid about 120 from eBay.
 
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It's really not that big. It's just wide, but fins are pretty slim. On the kj crd I have, I installed a bigger one, but I occasionally tow. Price - Wise, it's also not too expensive either, for a new unit. A serpentine cooler that's about half size is over 50 bucks. For this stacked plate cooler, you don't even need a thermal bypass, aw4 heats pretty well even in Cleveland winter. Imo, it's a good investment.

Btw, part number for this cooler is LPD 49211 and it's a tru cool.
 
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