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Auto Transmission Swap Compatibility

So you got it running with the new valve body that the seller gave you with the AW4 you boought? I bet you are feeling pretty good right now.
 
Yeah, sure did! It was incredible! The Jeep went from no drive to drive with just a short and fairly simple part swap. I love how serviceable the AW4 is! After about 3yrs of sitting the Jeep drives and shifts perfectly. I noticed that on start-up for a few minutes or until drive is selected that right out the front of the bell-housing it leaks trans fluid fairly bad, but then it goes away shortly. Some sort of heat expansion going on with the torque converter or the seals in that area. I don't think I am free and clear yet, but at least it moves under its own power and is capable of driving to and from town.
 
I never attempted removing the transmission so the stock torque converter is still bolted up. I am taking a big chance that it wasn't the torque converter that broke some teeth on the inside and that it wont continue to break and ruin my new valve body. I never was able to locate the exact part that broke or what the root cause was. I took apart my old valve body after I removed it and there were so many small parts and balls that fell out that there was no way for me to tell what broke, if anything, so I kept the solenoids (maybe good, maybe bad) and threw the rest in the garbage.

Honestly, a new filter/fluid, clean pan & magnets, properly working and oiled valve body/solenoids I feel like goes an extremely long way to resolving most trans problems. I knew how the Jeep had been driven when I bought it and I appreciate how durable and well built the AW4 is and I didn't want to see a great piece of machinery being taken out replaced and hauled to the salvage yard. Replacing a valve body and solenoids can be done in an hours time laying on your back under the trans while it's bolted up. I will warn: pay very close attention when removing the valve body when the transmission is bolted in the Jeep. The various sized piston springs, pistons, and plastic ball valve spring thingy will want to fall out along with more trans fluid! I had the benefit of having the 2000 AW4 sitting beside my Jeep upside down where I could see where everything went back properly.
 
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Does anybody have the Napa part numbers for the 1998 AW4 front transmission seals/o-rings I will need to have on hand to swap out when I pull the trans this weekend and identify my bell-house trans leak?

I am confused about how many seals between the torque converter, pump, and input shaft there are.

Thanks!
 
There should only be one seal, everyone calls it different things though. Seal part number from the dealer is 8350 3752, or a National 223830. A few companies are confused and list 30RH, 42/44/46RE/RH transmissions for the XJ, if your parts dealer wants to sell you a seal for one of those he is wrong.

I checked my 98 FSM and it looks like all the transfer case signals go through C107 (which is what I remembered, I just wanted to make sure) so yes, if you end up going 4x4, the 4x4 trans should bolt directly to the jeep and the wiring harness for it should just plug in.
 
Thank you Kastein! The issue where the parts are listed for different transmissions you described above was exactly what was confusing me. Are there any seals on the torque converter that I may want to have on hand in case they are bad?

Also, congratulations on having your photo on ROTM! Quite an honor!
 
I can't think of any, the torque converter itself is all metal on the outside. Its neck slides into the one seal you're replacing. There's a reaction shaft seal as well, but it's buried inside the transmission and I've never heard of one going bad, it's one of those things you just replace while rebuilding one.

Thanks - it's somewhat of a pile these days (well, it always was) and I forgot I even entered until the guy who does ROTM bugged me asking for higher resolution copies :laugh2:
 
So I pulled the transmission and sure enough I had a blown seal. Once I dropped the transmission I could not get the torque converter off by hand it would only move outward on the shaft slightly and seemed loose, but very stuck. I ended up bolting a chain to the bolts on the torque converter and giving it a few yanks it popped right off. My question is I thought the torque converter should've just slid right off? I noticed when I stick my finger in the torque converter and spin the inside spline with the tip of my finger there is a fair amount of play and it is not fixed on one rotational point. Is this normal or is it worn out? Below are a few photos.



 
The rotational play in the torque converter is fine, that's entirely normal as that component is held on its axis by the shaft going into it, rather than anything inside the converter itself.

I can't really tell as I wasn't there to do the pulling, but pulling torque converters on a tranny that's sideways can be a real bear, so that may have been normal. Similarly, getting the damn thing lined up and re-stabbed onto the transmission without removing it from the jeep and standing it on its end is going to suck really bad. It can be done, it just sucks and will be a bit of an arm workout. Make absolutely sure that the entire converter including the snout that seats into the crank bore is below the surface of the bellhousing, so if you put a straightedge across the bellhousing it clears it. On the spare one I have sitting here, the clearance between the straightedge and the snout is 3/16". If it won't seat, try lifting up and wobbling the converter side to side and rotating it 1/4 turn or so back and forth as you push it into the tranny.

Remember to pre-lube the seal lip and the neck of the converter with ATF before installing.

How does the neck of the converter look? Make sure it's not worn/galled/damaged in any way and that the two drive slots that engage the gerotor inside the fluid pump on the front of the transmission are in good condition.
 
Kastein, so after five minutes of trying to put the torque converter on with the trans sideways I quickly took your advice. lol I unhooked the last few things and completely removed the trans for a good cleaning and then literally stood the transmission facing up and joggled the lubed-up converter around and it popped right into place with the 3/16" plus straight edge to snout clearance you referenced. The shaft on the converter looked like a 150k mile shaft, but had no extreme wear, burs, or galling. I bolted the trans back up to the engine with everything nice and clean.

When I was just about to install my exhaust down pipe I saw the large factory crimp at the top of the pipe so I spent the next two hours to try pop the crimp out only to get nowhere! I thought it would help with the flow and performance of the exhaust and since I am 2wd I don't have to worry about front DS clearance, etc. I am thinking about just bolting it up with the dent, topping off the trans fluid, get the Jeep registered and worry about it later.

I took the opportunity to replace my rear trans seal as well. I noticed some light leaking from it. It would not pull out easy and broke my $7 Harbor Freight seal pick in half. Go figure! the replacement seal that the parts store gave me had a smaller depth on the surrounding metal ring seal flange than the OEM one I managed to get out. I installed the new one so the inside rubber seal was seated to the same depth in the back of the housing extension as the previous one. So I didn't press it in all the way just to the point where it was flush with the outside housing. I think it will be fine, but I will keep me eye on it for any leaks. Easy fix later.
 
The Jeep is all back together and seems to drive and shift great! I went to Smog it today and it Failed!!! The Jeep passed the Emissions Test portion easily based on the calculated averages on the report. However, it failed the OBDII Malfunction Indicator Lamp check and reported codes.

The Smog tech claimed the computer is reporting these codes:
P0700 = Transmission Control System Malfunction
P0740 = Torque Converter Clutch Circuit Malfunction
P1694 = Unknown Trouble Code

My question is that during my whole transmission removal process I never unplugged the battery or haven't really driven the Jeep enough at all for the computer to reset any codes that may have already been stored from the previous mechanical issues. Is it possible that these are just old stored codes and may clear out? I mean seriously after all the work I did and the Jeep starts and drives like brand new. Hard to imagine these types of codes are representative of the Jeeps current mechanical state!

No CEL is illuminated in the dash and I confirmed that the bulb is good and working. The OBDII system is new to me coming from my faithful, easy to diagnose 1992.
 
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Try clearing the codes with a borrowed parts store OBD2 reader, then pull the battery for 20 minutes with the key on and run it for a while. See if the codes stay away.

P1694 is a CCD bus communication error, I forget which one. It's either "TCU can't talk to ECU" or "ECU can't talk to TCU".
 
Thanks Kastein! I am curious, wouldn't the Jeep be having a heck of a time driving and shifting if these codes were reporting the Jeep's current operational state?
 
I doubt it. It might not have torque converter lockup if it was current malfunctions - you can test that easily enough.

The 16xx code just means the ECU and TCU can't talk (rather, one can't see messages from the other) which doesn't really affect anything except OBD2 fault detection. The ECU and TCU manage independently no problem, they just like to chat about what exactly is going on and report errors and will warn you about it if they can't.


... I forget, did you try unplugging the TCU and driving/trying to drive it when you first got it? Because that would certainly result in the ECU not being able to communicate with the TCU.
 
While I was trouble shooting the Jeep, before removing the transmission, I did unplug the connector to the TCU and tried running it for a while like this. Last night, I parked the Jeep overnight with both battery terminals unhooked and then today I took it to a local autobody shop and had them run the codes again. Their reading only showed two codes now:

P1694 = CCD Message from JTEC Failure
P0740 = TCC Solenoid C Functional Fault

Possibly the miles I have driven yesterday or the battery being unplugged cleared the P0700 code (or maybe a difference in the reader). The guy cleared the remaining two codes and showed me the screen as proof that he had cleared them. I might try to go in for another attempt at the Smog test either today or tomorrow.
 
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This morning I went in to the same guy for a smog re-test and the Jeep FAILED again! The tech said he had to fail it because turning the key to on never lights up the Check Engine Light and it never has. Having recently moved from Washington to Cali I am new to the whole smog thing... the computer now reports two codes, slightly different than yesterday:

P0700 = Transmission Control System Malfunction
P0740 = Torque Converter Clutch Circuit Malfunction

At this point I am almost feeling like there could be an ECU type issue. The check engine not illuminating is funny (even on start) and the smog tech thought I was trying to pass it by him with a pulled bulb. I am going to do some wire tracing/cleaning, check grounds for TCU and ECU, and verify my connections are all the way seated to these. When I was trouble shooting a few weeks ago I unplugged all three connections to the ECU and the one for the TCU. I am also going to try a different method to reset the ECU that I read today: http://www.quadratec.com/jeep_knowledgebase/article-89.htm
 
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Hey guys, so I am selling the 4x4, yr 98-01 XJ AW4 trans left over from this Jeep project and there is a guy on Craigslist that wants to know what is required to swap it into his 2001 Jeep Grand Cherokee 4x4 with a 4.7 engine? How much work in modification is required for this type of swap? Thanks!
 
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ohhhh boy... yeah that isn't gonna work at all without a ton of work. Sorry :(

4.7 shares a bellhousing pattern with the 5.2 and 5.9, rather than the 4.0, unfortunately. So he'll need to make a custom bellhousing adapter plate (if no aftermarket one exists), a custom flexplate and/or torque converter setup, and the electronics are gonna be a barrel of laughs too. I'm not really sure I'd recommend it.

If he had a 4.0 it'd be much easier, but even so, it's going to require a lot of electronics fun to make it work without setting the CEL.
 
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