Jeep wrangler transmission slips between shifts when cold

[2000Trooper]

I’ve got a 2012 wrangler jku with 200k on her. On hot days she still drives great. When it gets cold the transmission slips between shifts until the fluid gets warm. Alternatively if you put it into sport mode it shifts fine, granted it shifts at higher RPM when you do this. Though I would think the higher RPM would cause more slip. The transmission has been serviced regularly and currently the fluid looks new and is at the correct level. Used transmissions for these things can set you back 2-3k from a recycler for a unit under 100k miles. What are your thoughts on what’s causing this behavior? My transmission knowledge isn’t the best though I can wrench. If it’s clutch packs or the bands that have worn out it’s out of my league. But if it’s a solenoid or two then I can do something like that, however I don’t want to throw money away just putting in parts.

 

[racer12306]

Which transmission is that?

 

[Jetronic]

I'd look for a fluid that is thinner when really cold for the next change. The 40C viscosity is not much help here, I'd look at -40C viscosity if it's known, or anything that resembles cold start temperatures.

Filter is clean and fluid is correct for the, right?

 

[clinebarger]

Which transmission is that?

Should be a NAG1

 

[oldhp]

I would go to a real life transmission shop and let them run cold line pressure and see what a scope shows as it warms up. Don't those have a trans fluid thermostat? "Maybe" it's sticking and not letting full line pressure when cold.

 

[ripcord]

Does it do it if you put it in first and manually shift it through the gears?

 

[joegreen]

Should be a NAG1

If it is a nag1 they are quite robust. I would try and solve the problem before replacing.

 

[Bailes1992]

Are you sure this isn't normal?

Both my '18 and '19 Volvo V40's with an Aisin TF71SC used to leave the torque converter unlocked which can make it seem like slip until the fluid got to a set temperature. I think my Wife's Saab 95 with an Aisin AW55 used to do it too.

 

[totegoat]

The NAG 1 or W5A580 transmission not holding correctly can be caused by a faulty clutch, faulty solenoid, lack of fluid or fluid contamination according to a search. Good luck.

 

[Lubener]

Your transmission has "morning sickness". Internally with age, rubber seals harden, parts stick and do not do their job well when cold and soften or free up and start doing their job as the fluid warms. Other than doing repairs on the transmission, you could try an additive such as lubeguard or Seafoam which may address these issues.

 

[PontiacHO]

Comment above regarding hard clutch pack seals is correct. There are many “trans tune up” products out there to try. Some may actually help - for a while.

 

[demarpaint]

I'd give the LG red a shot, that's if the fluid is clean, at the proper level, and the transmission was recently serviced. I would not add a solvent type cleaner additive though. Over the years LG brought a few transmissions that were questionable back to operating properly for a few friends I helped.

 

[Chris142]

Does that one need the level checked in park or neutral? It matters.

 

[demarpaint]

Does that one need the level checked in park or neutral? It matters.

In PARK.

 

[atikovi]

With 200k, sounds like a valve body problem.

 

[Chris142]

In PARK.

And it says park on the stick?

 

[demarpaint]

And it says park on the stick?

I haven't looked at the stick in a while. It says park in the owner's manual, along with the procedure they want you do use to check the level with the dipstick. I use this: Dorman Dipstick Tool instead of the dipstick, along with a temperature chart when I service mine, and follow the shop manual directions.

 

[KiNETiCA]

Drop the valve body unit and see how much metal debris accumulated on speed sensors (they are magnetic and stronger than pan magnet)

 

[2000Trooper]

I'd give the LG red a shot, that's if the fluid is clean, at the proper level, and the transmission was recently serviced. I would not add a solvent type cleaner additive though. Over the years LG brought a few transmissions that were questionable back to operating properly for a few friends I helped.

This stuff?

I’m guessing if an additive like this works then it points the finger at worn clutches and seals correct? My understanding is that these just thicken the atf a bit?

Lubegard 60902 Automatic Transmission Fluid Protectant, 10 oz https://a.co/d/6BeEeHG

 

[2000Trooper]

Are you sure this isn't normal?

Both my '18 and '19 Volvo V40's with an Aisin TF71SC used to leave the torque converter unlocked which can make it seem like slip until the fluid got to a set temperature. I think my Wife's Saab 95 with an Aisin AW55 used to do it too.

It did not always do this. So I’m sure. Unless the government is forcing over the air updates lol