42RLE transmission temp problem

[richardh]

I have a 42rle, with a correctly installed derale 20561 cooler, and I'm having a temp problem.

I know I have a temp problem because I finally installed my tranny temp gauge... That's a procrastination story for another time. My gauge is reading 190 or with the probe in the pan, and my ODB2 Scanner is reading 215 from the TCM. Both at the top end of comfortable, and that's just around town.

In diagnosing and poking around 2 things stood out to me:

Lots of dust in the cooler, so I spent a health chunk of time cleaning with a air gun. Note to self, this makes the maintenance list from now on.

The return line is leaking at the 180 bend of the return hose supplied by Derale.

For reference the derale is plumbed

42rle out -> factory hose -> radiator in -> radiator out -> derale hose -> derale cooler in -> derale cooler out -> derale hose with 180 and leak -> factory hose -> 42rle in

Seems I have 2 choices
1) make a hose that goes from the return side of the cooler direct into the transmission. I'm proposing removing the hose with the 180 and the factory hose

42rle out -> factory hose -> radiator in -> radiator out -> derale hose -> derale cooler in -> derale cooler out -> hose I make -> 42rle in

2) repair or replace the derale hose with the 180 and leak and retain the current plumbing.

I'm inclined to just make a short direct hose and get that whole 180 bend out of the system.

if you look at Jerry Banford's install post from years ago, it's the 180 hose in the 3rd and 5th picture.

Has anybody seen this leak? And, what repair did you make?

 

[NashvilleTJ]

OK - before you bump this thread yet again, it is tough for anyone here to provide any helpful info because you have shared nothing about your rig. Year, engine, etc. A few pictures of your setup and problem would help as well. Your profile is not complete, and you have provided very little info here.

A correctly set up Derale cooler does not tell us much either, because it is not a great setup to start with. Is the fan working properly? Have you confirmed that fluid is actually flowing?

If you are just looking to fix the leak, that’s easy. But if you are looking for input on the temps you are seeing, we need a bunch more background.

 

[richardh]

Fair, I added my 05 to my profile.
05 TJ, 4.0, 42rle tranny, Lifted, 4.88 gearing, 35" tires
Derale fan is working correctly
I've not done a fluid flow test, I will do that tomorrow.

I did change out the hose for a hose I made, so the leak is fixed, and the temps are down in my test run.

 

[jjvw]

Fair, I added my 05 to my profile.
05 TJ, 4.0, 42rle tranny, Lifted, 4.88 gearing, 35" tires
Derale fan is working correctly
I've not done a fluid flow test, I will do that tomorrow.

I did change out the hose for a hose I made, so the leak is fixed, and the temps are down in my test run.

Deeper axle gearing will reduce the trans temps a bit because the transmission won't be working as hard to push 35" tires. And the Jeep will be nicer to drive.

 

[Gilaguy23]

let me throw this out for those who have experimented on auto's & gearing. Granted this is on my 99 superduty, which a few early years, including this one, Ford never ran trans cooler lines to thru the radiator, only to a cooler. My observations after 4 cross country trips pulling a 10K trailer. With the load O/D is basically worthless unless your on perfectly flat ground. I'll run hours in 3rd @ 2400 rpm and maintain trans temps at about 195 or just above. Things feel happy there when loaded down. When I can use O/D I will, I then see a 20 degree drop in trans temps regardless of me cringing while trying to run in OD, pushing the gas harder feeling like I'm killing the trans trying to save some rpm's or gas. My point is more RPM's can/will create more heat. So will going to 5.13's hoping to cool the trans work or be worth the cost?

 

[richardh]

Deeper gearing is in the plan, working on the budget part of that equation. The deeper gearing is more for crawling around in the rocks than for highway driving. I only drive my rig on the roads to get to and from trails.

 

[NashvilleTJ]

Deeper axle gearing will reduce the trans temps a bit because the transmission won't be working as hard to push 35" tires. And the Jeep will be nicer to drive.

My thought is that the deeper gearing also allows the torque convertor to reach lockup quicker, and stay there longer. I think slipping the torque convertor must be the biggest single cause of the heat.

In my Jeep, if I run a slow trail in high range, the tranny heats up very quickly. Switch to a lower range and the heat drops almost as quickly.

 

[jjvw]

Deeper gearing is in the plan, working on the budget part of that equation. The deeper gearing is more for crawling around in the rocks than for highway driving. I only drive my rig on the roads to get to and from trails.

The deeper gearing primarily is for highway driving. And it also improves crawling.

 

[richardh]

My thought is that the deeper gearing also allows the torque convertor to reach lockup quicker, and stay there longer. I think slipping the torque convertor must be the biggest single cause of the heat.

In my Jeep, if I run a slow trail in high range, the tranny heats up very quickly. Switch to a lower range and the heat drops almost as quickly.

Thank you, I believe this is solid advice. It's the 2nd I've heard it; I learned the do trails in low range to preserve the tranny advice last week from a fellow wheeler. I hope it helps. When I go out on Saturday with my spiffy new temp gauge, I will be able to tell.

 

[richardh]

Also, I threw a P0218 DTC tranny overheat last time I was out. Advice I can find on the internet says change the fluid including gravity flushing the system. So, I'm going to do that before this weekend also.

Shameless plug for the Harbor Freight ICON T7 diagnostic computer, it just works.

 

[jjvw]

Thank you, I believe this is solid advice. It's the 2nd I've heard it; I learned the do trails in low range to preserve the tranny advice last week from a fellow wheeler. I hope it helps. When I go out on Saturday with my spiffy new temp gauge, I will be able to tell.

I've not heard that one. I often do trails in low range to get through the trails.

 

[Gilaguy23]

Thank you, I believe this is solid advice. It's the 2nd I've heard it; I learned the do trails in low range to preserve the tranny advice last week from a fellow wheeler. I hope it helps. When I go out on Saturday with my spiffy new temp gauge, I will be able to tell.

One of my diesel ram trucks used 2 coolers in a series. The second was under the bed behind the drivers side layed flat and had a fan and shroud covering the entire cooler. Going slow obviously means little air movement across the cooler even when the engine fan is turning IMO.

 

[B.E. Coyote]

I'm no expert at all but I did just order that same cooler and have been reading about the install.

In probably the main install thread here, there was conversation about whether black (typically ground) wire should be used as power and the power wire used as ground for the fan to pull instead of push or vice versa. OP said reverse but later posters said that was incorrect. I am not saying who was right.

Not sure if maybe you followed that thread to install. Did it ever work correctly?

NashvilleTJ, why do you say that it isn't a great set up? I think you are the first I've seen with a negative comment.

 

[richardh]

I didn't follow the thread because it was installed by OP. However, I did read the thread and instructions to validate the install of my cooler. Derale recommends wiring the fan as a puller fan for maximum cooling, so that blue wire to hot as I recall. I check that my fan is indeed pulling by ensuring the air flow is through the cooler out the fan using my hand to feel the air move.

The one change I just made is to remove the factory return line and make a custom hose from the return side of the cooler directly into the return side of the 42RLE. That shortened the hose by quite a bit, and the return no longer runs next to the cats and exhaust twice.

To do that, get the following:

1/2" NPT to -6AN straight
Permatex 54540 Pneumatic and Hydraulic
2 -6AN Push lock 90 degree bends
5' of push lock SAE J1532 (that's important) hose
hose clamps for the hose

 

[NashvilleTJ]

...

NashvilleTJ, why do you say that it isn't a great set up? I think you are the first I've seen with a negative comment.

Personal experience.

I ran one behind a supercharged 4.0 and the 42rle. It was crazy loud (for me, embarrassingly loud), very vulnerable to damage - especially if you mounted it as recommended (as Jerry did), and in my experience it did not do a great job at cooling. It helped, but I routinely saw temps under heavy load well over 200 degrees. I did mount mine tucked up high next to the tub, so it was a bit safer up there - but even there an encounter with a sharp stick would put your tranny out of commission. And really making it safe from damage compromises the airflow.

A dedicated cooler mounted in front of the radiator is a much better solution IMO. It is what I run now in front of the Hemi and a 545RFE. It is quiet, safe from damage, and much more effective at cooling. My current cooler is much, much larger that that Derale unit.

 

[B.E. Coyote]

Personal experience.

I ran one behind a supercharged 4.0 and the 42rle. It was crazy loud (for me, embarrassingly loud), very vulnerable to damage - especially if you mounted it as recommended (as Jerry did), and in my experience it did not do a great job at cooling. It helped, but I routinely saw temps under heavy load well over 200 degrees. I did mount mine tucked up high next to the tub, so it was a bit safer up there - but even there an encounter with a sharp stick would put your tranny out of commission. And really making it safe from damage compromises the airflow.

A dedicated cooler mounted in front of the radiator is a much better solution IMO. It is what I run now in front of the Hemi and a 545RFE. It is quiet, safe from damage, and much more effective at cooling. My current cooler is much, much larger that that Derale unit.

Without a fan?

 

[NashvilleTJ]

Without a fan?

If you are asking about the cooler mounted in front of the radiator, no, there is not an integrated fan as with the Derale setup. The reason to mount it in front of the radiator is to take advantage of the engine fan.

This is my current setup. The tranny cooler is on the bottom. The cooler on the top is for the hydro-assist steering and brakes.

 

[jjvw]

If you are asking about the cooler mounted in front of the radiator, no, there is not an integrated fan as with the Derale setup. The reason to mount it in front of the radiator is to take advantage of the engine fan.

This is my current setup. The tranny cooler is on the bottom. The cooler on the top is for the hydro-assist steering and brakes.

View attachment 704038

View attachment 704039

Same setup on mine. Derale for PSC hydro assist steering on top and Setrab for the 42rle on the bottom.

Jerry's continued insistence on the fan cooled Derale trans cooler was long outdated quite a while ago.

 

[B.E. Coyote]

Well dang....
You guys still using oem radiators and fan clutches or are you electric?

I just got my cooling sorted with the traditional set up. I'd be a bit hesitant to put anything else in front of the radiator.

 

[jjvw]

Well dang....
You guys still using oem radiators and fan clutches or are you electric?

I just got my cooling sorted with the traditional set up. I'd be a bit hesitant to put anything else in front of the radiator.

Cooling is entirely factory. And mine has a supercharger. Engine temps rarely lean past straight up 210. Trans temps rarely exceed the low 200s.