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High Milage Transmission Flush - 96 ZJ

15K views 47 replies 10 participants last post by  herculeesjr 
#1 ·
I have a 96 ZJ 4.0. Bought cheap from a couple in Kentucky while I'm here at Fort Knox. Bought it with 174k, for only $1500. Did tune up, new tires, shocks, brakes w/rotors. At 180k I did a fluid and filter pan change on the Transmission.Since I bought it the transmission had a slight slip here and there, especially when cold, but I drive highway home once a month back north near michigan. Driving that long haul is pretty easy going and not many issues, especially after the long haul, when the tranny is hot, it shift a little easier, but you can tell it is having trouble. I know there are a bunch of "Do not Flush High Mileage" forums, and I understand that. I would like to do a fresh fluid flush without the middleman, doing it myself. I understand that doing a pan drop only does 4-5 quarts most of the time, and that the filter is good for 30k, so I'd like to not drop the pan and get most of the dirty fluid out, put new in. Im using MaxLife DexIII at the moment. Any suggestions on Fluid for high mileage trannys? Whats the process of disconnecting a "hose" and running old fluid out with engine started, few quarts at a time, while shutting down engine and refilling the fluid? I also SeaFoamed my Engine today. Just did the Crankcase and gas, didnt have a buddy to help with the vacuum process. :( Hope that goes well with my next oil change in about 30-40 miles. *just running it through then doing the change.*
 

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#2 ·
You should be using atf+4 in the Trans. Unless you did a complete flush, which it sounds like you didnt, you will now have a mix of dexiii and atf+4. At this point you will probably have to do the full flush.

Not sure which line to disconnect to flush the entire system, I would assume the return line would be the one you want so you can push all the old fluid out of the system.
 
#3 ·
Yes you need Dex +4 ...... I'd say take it to a shop an get a full flush .. I like the one done with B&G chemicals ..
and I'd say get the filter changed also ..
... If it had 174000 and never had a flush that's a bunch of mile but if it has 260000 like my haul truck but it has had a fluid change or flush about every 30k. and it has had 2 trans in it. So who knows.
 
#4 ·
@sebian Do you know where the return line is located? Also, would the mix of DexIII cause the slip? cause its a strange slip, its like it doesnt know when to shift. Thing is, if I know its missing, like its reving high, if right before it shifts, I give it a nudge on the gas, maybe 500rpm push, it will then shift more smoothly when it actually goes to shift. If I do continuous pressure, like an average driver, its like it is shifting kinda late. Im thinking solenoid issue? with that High of miles, would a complete flush be a good answer? The previous owners were the original owners, and they DID NOT TAKE CARE OF HER. :( Oil was black and thick, Tranny Fluid was black, and the pan had SO many shavings and build up.
 
#8 ·
After doing research, since I do NOT want to do a flush, and I am inexperienced with the Pan and all, I am going to do a siphon trade, take 4 quarts out, put 4 quarts in, through the dipstick port. I'll do it every week for the next month so that in the end I have NEW ATF+4 in my Transmission, and still have 20k left on my Filter.

AS Done HERE.
 
#10 ·
Went to walmart and got the siphon kit and 2 gallon jugs of water for the old fluid/new fluid, drove back,Checked my fluid in Neutral while running today after a 25 min drive, so it was nice and warm, and it was reading below minimum...checked it 3 times... So I added 2 NEW quarts of ATF+4, drove it for 10 min, and now she sits... I checked it and it is at max right now but with the full fluid circulation, I might need 1 more quart possibly. Thats not good! I drove like 8k since my last pan drop and if we didn't put in enough fluid, talk about OVERHEATING. Great way to ruin the trans... Im hopeful though, I'll check over the next few days and monitor the fluid level. Once I get it to the right level, I will then pull 4 more quarts of old and put in new... the cleaner the fluid the better.
 
#13 ·
#14 ·
Just my 2cents I would recommend doing a complete transmission flush, new filter, adjust the bands, and adjust the kickdown cable.
I did so to my Jeep about 10k miles ago (just hit 150k) minus adjusting the bands and it shifts fine, kickdown cable fixed weird shifting points and the flush quickened shifts into gears. Me personally I do not believe in all of this do not flush high mileage transmissions stuff, though I only use AMSOil https://www.amsoil.com/shop/by-product/transmission-fluid/automatic/synthetic-multi-vehicle-automatic-transmission-fluid/?code=ATFQT-EA so that could of made a difference to where I ended up not having problems.
 
#15 ·
did the pan drop and filter less than 8k ago... why would I do it again when I'd be doing the same thing, pulling oil out and putting in new... this is why i'm using the siphoning technique... and its one thing if a few people say it not to be flushed after a certain point, but when 90% of people both amateurs and vet mechanics all say the same thing about it... yeah, i'll listen.
 
#17 ·
The problem with flushes is you can easily run it low in the process. The best thing to do is a series of pan drop fluid oil changes. I use a marine oil changer to suck as much out of the pan thru the dip stick and the drop the pan with no mess.
 
#18 ·
I would start with adjusting the kick down cable. The shifting issue you describe sounds like an adjustment issue. You will see information about doing this in the Haynes manual. If you don't have one, go get it. Best $20 beans you'll spend.

Next I would have a shop drop the pan, adjust bands and leave filter alone since you just recently replaced it.

If you can drop the pan, go for it. If it makes you weary, don't. Trannys are not cheap.

Btw, that's a very decent ZJ. Especially for $1500 buckaroos…

Sent from my Raul iPhone using JeepForum
 
#21 ·
I would start with adjusting the kick down cable. The shifting issue you describe sounds like an adjustment issue. You will see information about doing this in the Haynes manual. If you don't have one, go get it. Best $20 beans you'll spend.

Next I would have a shop drop the pan, adjust bands and leave filter alone since you just recently replaced it.

If you can drop the pan, go for it. If it makes you weary, don't. Trannys are not cheap.

Btw, that's a very decent ZJ. Especially for $1500 buckaroos…

Sent from my Raul iPhone using JeepForum
I live near Louisville, Radcliff/Fort Knox area, and would like to know where a good shop would be to adjust the bands, do the pan drop/filter change, plus new ATF+4 for a decent price... also is the Kick Down cable where the pan is? or deep inside? cause that is a nogo for me, inexperienced hands + transmission = BROKEN/NOT GOOD. I learned a long time ago, if you don't know something, ask how to do it, watch it be done, then repeat the steps, never go on a whim and do something new without reading up. Which is why I have JeepForum! :highfive:
 
#19 ·
@porrsher, I appreciate it! but she did NOT look like that when I got her, she was sitting in a Kentucky Backwoods area with green sap and leaves covering it up bad, tires bald with wires, shocks rusted completely. She is in good hands now, I replaces the brakes(both rotors, and pads- mid grade, not cheapo stuff), Brand new tires (thank you for Walmart putting on the wrong weight ratio tires, they had to upgrade me to the only set of 4 in stock, original price I was going for $390 set of 4, at $412, I got a set of 4 that were SUPPOSED to be $138 a tire!), New shocks(mid grade as well), new valve cover gasket, new plugs, wires, distributer, radiator (+ all new hoses)... new bulbs in EVERY light (interior+exterior) and just some chrome fogs on the front, I liked how it looks with the chrome grill. So far so good, but want to get her running 100% to get her past 250k at least. everything works on her too, even A/C and Cruise!
 
#24 ·
@LouC and @herqulees Both are AWESOME, AS being a noob, had no idea about the drain plug of differential! and I will check my kickdown cable now!

I also siphoned out 3quarts today through my dipstick port, here is a side by side of the fluid, obvious which is the new! What I removed was TERRIBLE... and cause I was at the max, I went ahead and left out 3/4 quart of new. I will drive around a week and repeat this process for 2 more quarts, then I will wait to do it all again at next oil change, until my fluid is nice and red! ;) What are your thoughts on this, since I just changed less than 8k the pan fluid and filter...? NO, I didnt do the trans tune, not going to either.

I also Degreased my engine bay today with PURPLE POWER! :) Stuff works GREAT! I had buildup behind the serpentine belt, the intake, valve cover, back wall, everywhere! but this stuff helped strip it off and clean! awesome stuff!
 

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#25 ·
We never recommend doing a trans flush on high milage 42re's. Believe it or not, that dirt is holding everything together.
 
#28 ·
happens all the time. its a dealer only clip
 
#30 ·
yup gotta order it. This is why we make the big bucks haha
 
#32 ·
cable, unless you find a weird clip
 
#36 ·
Going from my memory of what the clip looked like that looks like an exact replacement to me. FYI the Jeep is still driveable, however I would not recommend any further than across town as the transmission no longer knows how to adjust it's shift points so it will pick the wrong gear a lot. I ended up driving about five miles on 45mph roads to a WalMart for superglue, other than accelerating from a stop (it would shift first - second - first (for a split second) - second - third) it was still driving fine.
 
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