How to flush the automatic transmission on your Jeep Wrangler TJ

Chris

Administrator
Staff Member
Sep 28, 2015
30,138
18,193
Salem, Oregon
#1
This flush was done on a 32RH transmission, but the procedure should be mostly the same for a 30RH and 42RLE transmission as well.

I wanted to replace the filter and get all the fluid out of the torque converter. So I thought I would give it a try. There were some questions I had, but I was sure I would figure it out.

I worked at a Jiffy Lube for a couple years before college back in the 90s. I replaced many tranny filters. I also performed flushes with the T-Tech machine. That machine makes the transmission fluid flush much easier, and if you don't mind dropping $120 or so, I suggesting going that route. Basically the machine pumps 5 or 6 quarts of new transmission fluid through the lines, flushing out all the old stuff in the process, and replacing it with the new stuff. It's clean, mess free, and you can literally watch the old, dark, nasty fluid come out of your transmission while the new fluid goes in. However, if you don't mind getting dirty and want to do it yourself, follow this procedure.


Supplies
- 3/8" (inside diameter) flexible clear plastic tube (5 feet give or take)
- 5 gallon bucket
- Wide drain pan
- 12 quarts ATF+4 transmission fluid
(See Wrangler TJ Fluid Capacities for your transmissions fluid capacity, remember that the large number of extra quarts we are buying is to flush all the old fluid out!)​
- Transmission filter & gasket (click on the link below for your model)


Removing Pan
I cleaned the exterior of the pan and tranny of any mud or dirt. Just to avoid getting any in the tranny.

Since the back 1/3 of the pan is covered by the transfer case skid I decided I would drain the fluid from the front. I loosened the front bolts almost all the way out. Then loosened all other bolts working my way backwards down each side simultaneously. I kept the rear bolts tight. It ensures the front side of the pan separates from the tranny and the fluid comes out the front. I gently pried the front of the pan since it was still sticking to the tranny.

1-Drain.jpg



Once the fluid is done draining I removed the pan and filter. Without a drain plug the pan still has fluid in it. Wiped off the mating surface and remove any stuck gasket. I used a gasket scraper. Then wiped a rag with brake cleaner to finish cleaning the surface. Installed the new filter. Apparently, there are torque specs for the filter bolts. I had no idea at the time.

2-Filter.jpg



Clean the pan
I cleaned the pan with brake cleaner. Removed the magnet and cleaned it as well. Then washed in hot soapy water in the kitchen sink. Quickly dried and cleaned again with brake cleaner to remove any moisture quickly. Put the magnet back in and matched up the correct gasket. My kit came with 2. Put the bolts through the pan holes and screwed into gasket. The gasket holes are small enough to hold the bolts. It's important not to screw the bolts in the gasket all the way. It would make it difficult to screw the bolts into the tranny because all the other bolts are fully extended. I put them in so the bolts are sticking out of the gasket a couple threads (even though the picture shows them screwed in fully).

3-GasketInstalled.jpg



Attach Pan
I put the pan up to the tranny and screwed in the bolts. Do not over tighten them! It may mess up the gasket or worse snap a head off. I've done that before. I lost 2.5 quarts of fluid after dropping the pan. I lost some more in spillage. So I put 3.5 quarts in. Now the pan is 1 quart over full. I did not know if another quart would overflow the dipstick tube, so I didn't add anymore, though I probably could have.


Get Ready
The passenger side tranny cooler hose that attaches to the radiator is the one I want. I disconnected from tranny and let hang. Attached the 3/8" plastic tubing to the radiator and secured inside bucket.

4-CoolerHose.jpg



I chose a 5 gal bucket because they're cheap and I can easily see the fluid level through the plastic. I took an empty and clean milk gallon and added one full of water at a time to the bucket. I marked the level with a permanent marker on the side. Then estimated each section into quarters for quart graduations! I got the remaining 9 bottles of ATF and removed the caps. I kept them near the tranny dip stick tube for easy access.


Flush
I applied emergency break, put in neutral, then started. The old fluid started coming out the hose and into the bucket.

5-Bucket.jpg



I started adding fluid down the dip stick tube as fast as possible. Unfortunately I couldn't keep up. It was too quick. I hear park is slower, I'll do that next time. I had to shut the car off about 3/4 the way through to get caught up. You don't want to run it dry. I did notice a gap in the fluid coming out of the tube a few times. That was probably because I couldn't keep up.

So I went through 11 quarts total. I left the 12 quart in case I needed to add any.


Finish
I reconnected the tranny cooler line. Started vehicle and shifted through the gears a few times. Put in neutral and checked fluid level. It was good. After driving around a day or two I checked the level again when it was hot. I had to add a little. That's it!
 
Likes: GTboosted

lrb6805

Die Living
Supporting Member
Jun 19, 2017
96
109
Grapevine, TX, United States
#2
I did this today, but on my ‘06 Lj with the 42RLE Auto and there are some slight differences. It took me a long time due to a lot of complications and first time doing this on a jeep. In the future I could do this in less than an hour knowing what I know now.

Some things that are different on the ‘06 (so people are aware) is that the clear hose needs to be attached to the metal tube the goes into the radiator. I tried to put it in the hole in the radiator instead like shown above and ended up spraying ATF everywhere. Just make sure to attach it to the metal pipe that is in the exact same location described above. Also, Id use something to clamp it because the clear hose slipped off the metal pipe and again made a mess.

Also, if you have a skid plate...good luck. You have to remove it to be able to change the transmission filter. My bolts just spun in place and I was already too far into it to take it somewhere to be removed. So due to a lack of certain power tools, i had to use a hand saw to cut it off. So I would suggest making sure you can remove the front skid plate protecting the pan long before draining anything.

Other than that, the process was as shown above.


Sent from my iPhone using Tapatalk Pro
 
Likes: Chris
OP
OP
Chris

Chris

Administrator
Staff Member
Sep 28, 2015
30,138
18,193
Salem, Oregon
#3
I did this today, but on my ‘06 Lj with the 42RLE Auto and there are some slight differences. It took me a long time due to a lot of complications and first time doing this on a jeep. In the future I could do this in less than an hour knowing what I know now.

Some things that are different on the ‘06 (so people are aware) is that the clear hose needs to be attached to the metal tube the goes into the radiator. I tried to put it in the hole in the radiator instead like shown above and ended up spraying ATF everywhere. Just make sure to attach it to the metal pipe that is in the exact same location described above. Also, Id use something to clamp it because the clear hose slipped off the metal pipe and again made a mess.

Also, if you have a skid plate...good luck. You have to remove it to be able to change the transmission filter. My bolts just spun in place and I was already too far into it to take it somewhere to be removed. So due to a lack of certain power tools, i had to use a hand saw to cut it off. So I would suggest making sure you can remove the front skid plate protecting the pan long before draining anything.

Other than that, the process was as shown above.


Sent from my iPhone using Tapatalk Pro
Thanks for that update, I’m certain that will help someone in the near future.
 
Feb 17, 2018
77
25
North west arkansas
#4
I know this is a old thread but I'm curious if a aluminum pan would benefit the transmission to run cooler. Not sure if they even make one cause I haven't searched yet but my mind was just wondering.
 
OP
OP
Chris

Chris

Administrator
Staff Member
Sep 28, 2015
30,138
18,193
Salem, Oregon
#6
I know this is a old thread but I'm curious if a aluminum pan would benefit the transmission to run cooler. Not sure if they even make one cause I haven't searched yet but my mind was just wondering.
I don't think so. If you want the transmission cooler, you need to install a transmission cooler such as the one Jerry and I run:
How to install a Derale 20561 transmission cooler on your Wrangler TJ

Do you need to use loc-tite on the pan bolts?
I don't know for sure, but the FSM will say for certain:
Jeep Wrangler TJ Factory Service Manuals (FSM) & Technical Documentation
 

cliffish

TJ Addict
Supporting Member
Oct 22, 2017
1,885
1,731
St James, NY, United States
#8
it wasn't bad on my 05, The only thing that differed is I could not find a barbed fitting to go on the cooler so I used one of those form a funnels to channel the fluid in a bucket. I could not really see the fluid coming out and was doing it myself so I added a quart, ran for a few seconds, shut it off and repeated it a few times.
 
Likes: Nicholas
Dec 3, 2015
84
53
Music City USA
#9
Did this flush yesterday on a 2003 just like the tutorial above except I put a 3/8" bolt in the removed line to keep it from dripping,
started the engine with the trans in park just like I was supposed to and proceeded to blow the bolt out of the removed line like it was a 30/30 rifle round. Apparently the lines were backwards from the factory or its different on a 2003 TJ, other than that it was easy to do. used 10 qts of fluid to do the whole thing flush and all.
 

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