Transmission issue when cold outside

SouthernLJ

SouthernLJ

TJ Enthusiast
Joined
Jan 13, 2022
Messages
190
Location
South GA
I have an '06 4.0 Auto LJ. When it's cold out, usually near freezing temps, my auto transmission can't find a gear at times. The last time this happened was a week or two ago. I have about a quarter mile drive to the end of my road, followed by an even shorter drive to the traffic light. I have to take a left at the light and if I give it gas, coast around the corner, when I go to get back on the gas, it's like it's in neutral. I give it gas and the motor just revs. I have to pedal it a little bit until it finds a gear. It sucks because I usually have cars behind me and if it can't find a gear, I have to make a decision whether to keep coasting and hope it finds a gear, or plan to pull off to the side of the road while I still have momentum.

I've tried letting the Jeep warm up more in the morning. I've given it about 5 minutes before taking off to no effect. This only happens occasionally, and always when I'm coasting around a corner and then getting back on the gas. I've started changing the way I drive by staying on the gas around corners. This never happens when it isn't cold outside, I'd say 35 degrees and below is when it happens. Also, it only happens after that short drive leaving my house. If I make it past the left turn off of my road, and the next turn at the light, I'm good. Once I've passed those two hurdles, all is good.

Any thoughts?
 
What he said. If you do a proper fluid check and it’s full, then you have an internal fluid leak. Usually one or more of the seals inside is bypassing until it expands a little from getting some heat in it. Idling won’t heat the trans up very fast. The trans only really generates heat under load. It takes a long time for engine heat to transfer to the trans internals.
 
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macleanflood said:
Have you checked the fluid level with the Jeep running and in neutral?

-Mac
Click to expand...

If you're getting at what I think you're getting at, the 42RLE pump runs in park as well as neutral, but it looks like he checked it while off which isn't the right way for any auto trans I've ever worked with. It does feel like a fluid problem like a drainback sort of thing only not within the torque converter like we sometimes see in the 32RH.

The fact that it's temperature related is odd....how cold is cold enough to exhibit the problem? How much warmer does it need to be to make it not happen?
 
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hear said:
If you're getting at what I think you're getting at, the 42RLE pump runs in park as well as neutral, but it looks like he checked it while off which isn't the right way for any auto trans I've ever worked with. It does feel like a fluid problem like a drainback sort of thing only not within the torque converter like we sometimes see in the 32RH.

The fact that it's temperature related is odd....how cold is cold enough to exhibit the problem? How much warmer does it need to be to make it not happen?
Click to expand...

The pump is driven by the hub of the torque converter so the fluid is flowing anytime the engine is running. One of the main reasons to check level while in gear is that a lot of transmissions don’t circulate fluid through the cooler till it’s in gear. Newer transmissions have a thermostatic flow valve that won’t flow till full operating temp. Hondas up through the 90’s, you’d check with the engine off. That’s the only ones I’ve seen do that. Not sure why. Not Jeep related, but if anyone knows…….
Transmission seals, especially the Teflon ones, love to leak cold when they get a good amount of wear on them. Heat swells them up. It’s the magic sauce in that trans fix in a can crap. Just agents to cause the seals to swell. Back in the day you’d add a quart of Ford type F fluid to cause the same thing to happen, and buy you a little time.
 
hear said:
If you're getting at what I think you're getting at, the 42RLE pump runs in park as well as neutral, but it looks like he checked it while off which isn't the right way for any auto trans I've ever worked with. It does feel like a fluid problem like a drainback sort of thing only not within the torque converter like we sometimes see in the 32RH.

The fact that it's temperature related is odd....how cold is cold enough to exhibit the problem? How much warmer does it need to be to make it not happen?
Click to expand...

I would say around 35 and below. It doesn't get too cold down here. I'm going to look at the fluid level tomorrow.
 
Geepum said:
The pump is driven by the hub of the torque converter so the fluid is flowing anytime the engine is running. One of the main reasons to check level while in gear is that a lot of transmissions don’t circulate fluid through the cooler till it’s in gear.
Click to expand...

Yes and no. He's got an 04 which means 42RLE, which means yes, the pump is flowing regardless, including park. You're new here so I'm just going to assume you didn't know that the older TJ's have the 32RH which does not run the pump in park. Or maybe I didn't understand the point you were trying to make.

Geepum said:
Transmission seals, especially the Teflon ones, love to leak cold when they get a good amount of wear on them. Heat swells them up. It’s the magic sauce in that trans fix in a can crap. Just agents to cause the seals to swell. Back in the day you’d add a quart of Ford type F fluid to cause the same thing to happen, and buy you a little time.
Click to expand...
Those teflon rings were what I was thinking, but I didn't really figure they were going to be that sensitive to temperature. At least less so than metal rings would be.
 
hear said:
Yes and no. He's got an 04 which means 42RLE, which means yes, the pump is flowing regardless, including park. You're new here so I'm just going to assume you didn't know that the older TJ's have the 32RH which does not run the pump in park. Or maybe I didn't understand the point you were trying to make.


Those teflon rings were what I was thinking, but I didn't really figure they were going to be that sensitive to temperature. At least less so than metal rings would be.
Click to expand...

I’m definitely new here. I have been a master auto tech my whole life and I own an 01 which I’m sure you know is the 32. I’ve changed bands, clutches, and seals in 3 so far. I’m not sure what you mean by the pump not running in park. The trans oil pump is in the very front of the case and is driven by the torque converter hub on all transmissions I’ve studied. If that pump wasn’t pumping the torque converter bushing would seize due to lack of lubrication since the torque converter housing is attached to the flex plate/flywheel. The notches on the very end of the torque converter snout is what drives the pump. Similar to how you have to have the t-case in neutral to flat tow or how the rear driveshaft has to be removed if you tow a rear wheel drive car on its drive axle. Also if the pump didn’t flow in park my apprentice wouldn’t have pumped 3 quarts of atf on the floor because he forgot to connect a cooler line after the trans flush. He just started it in park and let it run for 4 minutes. 😂 If there’s something I missed like the trans having a secondary pump, please let me know. I’ve seen that before on a few different trans.
 
Geepum said:
I’m definitely new here. I have been a master auto tech my whole life and I own an 01 which I’m sure you know is the 32. I’ve changed bands, clutches, and seals in 3 so far. I’m not sure what you mean by the pump not running in park. The trans oil pump is in the very front of the case and is driven by the torque converter hub on all transmissions I’ve studied. If that pump wasn’t pumping the torque converter bushing would seize due to lack of lubrication since the torque converter housing is attached to the flex plate/flywheel. The notches on the very end of the torque converter snout is what drives the pump. Similar to how you have to have the t-case in neutral to flat tow or how the rear driveshaft has to be removed if you tow a rear wheel drive car on its drive axle. Also if the pump didn’t flow in park my apprentice wouldn’t have pumped 3 quarts of atf on the floor because he forgot to connect a cooler line after the trans flush. He just started it in park and let it run for 4 minutes. 😂 If there’s something I missed like the trans having a secondary pump, please let me know. I’ve seen that before on a few different trans.
Click to expand...

I've rebuilt a couple as well but am by no means an expert. Maybe what we really mean is that while the pump might run in park, it doesn't push fluid in such a way to allow for a good fluid level reading (the FSM states it must be in N to check the level for the 32RH vs park on the 42RLE), but also other functions don't happen in park, such as re-filling the torque converter. There's a thread on the 1st or 2nd page right now where the TC is draining overnight and letting it idle in park does nothing to refill it. If they put it in N for a few seconds it immediately becomes drivable.

So it's probably/possibly a slight laziness in terminology, or maybe a total lack of understanding.

EDIT: DUH, I was referencing THIS thread. Recursion is recursive, what can I say.
 
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hear said:
I've rebuilt a couple as well but am by no means an expert. Maybe what we really mean is that while the pump might run in park, it doesn't push fluid in such a way to allow for a good fluid level reading (the FSM states it must be in N to check the level for the 32RH vs park on the 42RLE), but also other functions don't happen in park, such as re-filling the torque converter. There's a thread on the 1st or 2nd page right now where the TC is draining overnight and letting it idle in park does nothing to refill it. If they put it in N for a few seconds it immediately becomes drivable.

So it's probably/possibly a slight laziness in terminology, or maybe a total lack of understanding.

EDIT: DUH, I was referencing THIS thread. Recursion is recursive, what can I say.
Click to expand...

I totally agree that different things happen and fluid flows differently depending on gear which affects how various trans are checked. Like you said, torque converter drain back or fluid flow through the cooler, etc. I think we’re on the same page for what we’re trying to get after though. Now if only someone can explain why Hondas are checked not running. I’ve pondered that a long time. Thanks for the discussion. That’s why I joined this forum. It’s a rarity to have good technical convos with people willing to be open minded and not getting butt hurt. What is the purple on your Jeep in your photo by the way?
 
@SouthernLJ did you ever get around to checking your ATF level while the engine is running? Your symptom sure could be caused by the ATF being a little low. If it's low, just insert a small funnel into the dipstick tube and add ATF+4 until it's all the way to the full line and even a little over would be great. Where an automatic transmission is concerned it's far better for it to be slightly overfilled than even slightly underfilled.
 
Geepum said:
not getting butt hurt.
Click to expand...
There's no shortage of that here.

Geepum said:
What is the purple on your Jeep in your photo by the way?
Click to expand...

The purple is my Alien Sunshade which is actually the one for an LJ. I wanted the shade to extend further back so my kids could have some level of shade. I also just realized that picture is cropped, I'm actually next to some lovely swimming hole deep in the National Forest I found one day. Instead it looks like I'm just on a gravel road.
 
hear said:
There's no shortage of that here.



The purple is my Alien Sunshade which is actually the one for an LJ. I wanted the shade to extend further back so my kids could have some level of shade. I also just realized that picture is cropped, I'm actually next to some lovely swimming hole deep in the National Forest I found one day. Instead it looks like I'm just on a gravel road.
Click to expand...
hear said:
There's no shortage of that here.



The purple is my Alien Sunshade which is actually the one for an LJ. I wanted the shade to extend further back so my kids could have some level of shade. I also just realized that picture is cropped, I'm actually next to some lovely swimming hole deep in the National Forest I found one day. Instead it looks like I'm just on a gravel road.
Click to expand...

PM’d you.
 
Jerry Bransford said:
@SouthernLJ did you ever get around to checking your ATF level while the engine is running? Your symptom sure could be caused by the ATF being a little low. If it's low, just insert a small funnel into the dipstick tube and add ATF+4 until it's all the way to the full line and even a little over would be great. Where an automatic transmission is concerned it's far better for it to be slightly overfilled than even slightly underfilled.
Click to expand...

Hey Jerry, I have not had a chance yet. But I will. I do have some ATF+4 in the garage and will fill it to maybe an 1/8" (?) over the fill line if it needs some.
 
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