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Putting a 91 AW4/NP231 into my 90-I've got questions

BIGSLVRXJ

BIGSLVRXJ

NAXJA Forum User
Location
Des Moines, Iowa
Let me start off by explaining what's going on here. This is my first time messing around with this area of the drivetrain. I've had virtually everything that bolts onto the engine off of it but before, so I'm pretty confident I can do this, but when I had to replace the engine I had my buddy split the engine/transmission. I'm getting a transmission jack tomorrow and I plan to split the tranny and tcase in the Jeep to pull the old one out and split them to put the new one in. I figure that way the load is much lighter. As of right now I have everything besides the cooler lines and 4wd linkage off the sides of the transmission, so it's more or less ready to come out. I've also got a 99 intake manifold on so I'm running the 91+ TV cable too, so that's not a problem. Right now I've got the original 1990 AW4 and 231 which correct me if I'm wrong, the AW4 is a 21 spline output and the 231 is a 21 input right? The 91 AW4 I'm dropping in is a 23 spline all the way around right? I guess here are my questions...

1. As long as I'm doing the trans and t-case together there is no problem with compatability right? I assume I use my existing flexplate? So there is really no change as far as it bolting to the engine, it's only on the other end right?
2. I'm really worried about getting the torque converter seated against the pump correctly. It doesn't look like anyone matchmarked it at any point along the way, so am I screwed there? Also, is it hard to get it all the way against the pump?
3. I was reading in my Hayne's manual which I trust less than the distance I can throw it, but it says make sure to support the engine so it doesn't move. It also says to keep the trans and tcase level while pulling them and reinstalling. This put a halt to my plan because I planned to have the engine pivot downward to get to the upper bellhousing bolts and just in general for removing and reinstalling it. Why do they say to keep everything level? Is it just so fluids don't spill out?

I would really appreciate any help. I had my existing AW4 rebuilt two years ago and dropped almost $2000 and it's gone already. I'm not going to get raped again so this time I'm atleast going to try it myself. If any of you guys can contribute to help a newb at the drivetrain area it would be GREATLY appreciated.
Thanks,
Collin
 
Last edited:
No flex plate problem at all. Torque convertor bolts on the same way Renix or HO.

Apply a small amount of pressure on the front of the torque convertor while you spin it and if it is currently unlocked from the pump you will feel it slide in to the pump. It will set a ways back from the faceof thebell housing when installed correctly.

Tilt it anyway you want don't worry about it. Use that chiltons as knee pad. As long as nothing from the engine hits anything in the compartment such as the fan and the radiator go for it.

Have fun with it the AW4 is rather heavy and its supposed to rain all week around here.
 
comancheon33 said:
No flex plate problem at all. Torque convertor bolts on the same way Renix or HO.

Apply a small amount of pressure on the front of the torque convertor while you spin it and if it is currently unlocked from the pump you will feel it slide in to the pump. It will set a ways back from the faceof thebell housing when installed correctly.

Tilt it anyway you want don't worry about it. Use that chiltons as knee pad. As long as nothing from the engine hits anything in the compartment such as the fan and the radiator go for it.

Have fun with it the AW4 is rather heavy and its supposed to rain all week around here.
Click to expand...
Thanks dude, that makes me feel a little better. Don't worry you'll be getting called as I'm in the process, I just thought I'd give you a little break and see what these guys had to say about it.
 
No problem if it gets carried away I have your MJ has a hostage. LOL.
I called Brad and he will have the tires here by the weekend. I will need your wheels before then to get them mounted up.
 
RenixPower said:
Let me start off by explaining what's going on here. This is my first time messing around with this area of the drivetrain. I've had virtually everything that bolts onto the engine off of it but before, so I'm pretty confident I can do this, but when I had to replace the engine I had my buddy split the engine/transmission. I'm getting a transmission jack tomorrow and I plan to split the tranny and tcase in the Jeep to pull the old one out and split them to put the new one in. I figure that way the load is much lighter. As of right now I have everything besides the cooler lines and 4wd linkage off the sides of the transmission, so it's more or less ready to come out. I've also got a 99 intake manifold on so I'm running the 91+ TV cable too, so that's not a problem. Right now I've got the original 1990 AW4 and 231 which correct me if I'm wrong, the AW4 is a 21 spline output and the 231 is a 21 input right? The 91 AW4 I'm dropping in is a 23 spline all the way around right? I guess here are my questions...

1. As long as I'm doing the trans and t-case together there is no problem with compatability right? I assume I use my existing flexplate? So there is really no change as far as it bolting to the engine, it's only on the other end right?
2. I'm really worried about getting the torque converter seated against the pump correctly. It doesn't look like anyone matchmarked it at any point along the way, so am I screwed there? Also, is it hard to get it all the way against the pump?
3. I was reading in my Hayne's manual which I trust less than the distance I can throw it, but it says make sure to support the engine so it doesn't move. It also says to keep the trans and tcase level while pulling them and reinstalling. This put a halt to my plan because I planned to have the engine pivot downward to get to the upper bellhousing bolts and just in general for removing and reinstalling it. Why do they say to keep everything level? Is it just so fluids don't spill out?

I would really appreciate any help. I had my existing AW4 rebuilt two years ago and dropped almost $2000 and it's gone already. I'm not going to get raped again so this time I'm atleast going to try it myself. If any of you guys can contribute to help a newb at the drivetrain area it would be GREATLY appreciated.
Thanks,
Collin
Click to expand...


I second the no need to keep the engine level. But, you'll be surprised at how level it will sit in the engine bay with no trans/transfer attached. Got your E-12 socket for the two uppewr bolts?

What year did the speedo switch to electrical? You might have that issue to deal with...it's nothing more than swapping the pieces from trans to trans.

:repair:
 
John B said:
I second the no need to keep the engine level. But, you'll be surprised at how level it will sit in the engine bay with no trans/transfer attached. Got your E-12 socket for the two uppewr bolts?

What year did the speedo switch to electrical? You might have that issue to deal with...it's nothing more than swapping the pieces from trans to trans.

:repair:
Click to expand...
I've actually already replaced those stupid E-12 with hex heads so I'm good there. And yes, 91 was the changeover year so I will need to swap the different deal in but that part doesn't concern me. I figured the engine would level back out with no trans/or tcase on it, especially since I have MORE motor mounts I'm sure it'll get pulled right back up. Thanks for the tips.
 
Unbolt the t/c from the flexplate first and use a strap or something to keep it with the tranny. Going the other way, install the t/c onto the tranny first and use a wire or strap to hold it in when you install the tranny. That way you avoid putting too much of a side load on the t/c and you know it's properly engaged before you tighten up the bellhousing bolts (and damage the pump if it's not). You may find you need a chunk of wood and a bottle jack under the rear of the engine to line it up. I found a 2x4 shoved behind the valve cover helps keep it from tipping to far back as well. Of, if the NSS needs done it's much easier to R&R while the tranny is on the bench.
 
lawsoncl said:
Unbolt the t/c from the flexplate first and use a strap or something to keep it with the tranny. Going the other way, install the t/c onto the tranny first and use a wire or strap to hold it in when you install the tranny. That way you avoid putting too much of a side load on the t/c and you know it's properly engaged before you tighten up the bellhousing bolts (and damage the pump if it's not). You may find you need a chunk of wood and a bottle jack under the rear of the engine to line it up. I found a 2x4 shoved behind the valve cover helps keep it from tipping to far back as well. Of, if the NSS needs done it's much easier to R&R while the tranny is on the bench.
Click to expand...
I appreciate the tips, I got it out today and got the parts out of the 1990's to transfer to the 91 Transmission/T-Case and the old tranny is on it's way to the scrapyard. One of my buddies came over today and showed me how the torque converter goes onto the pump and there is an audible noise and feeling when it does. I'm not worrying too much about it, I'm just hoping I can get everything lined back up okay. I'll let you guys know how it goes. And I've heard some people recommending pouring a quart of fluid into the torque converter before reassembly to "prime it" so to speak. Is this really necessary?
Thanks again for the help so far.
-Collin
 
Might as well but its not necessary. If it was a bran new or rebuilt T/C then it would be highly recommended.

There is oil in the bottom of the T/C that will keep every thing lubed when you first start it.
Just make sure you have drained and refill the tranny pan before you start it.
I haven't done an auto in an XJ so i don't now for sure but i thing that dip stick tube has to be removed and if it's any thing like when you remove the pan to service it..............I't a PITA

Flash.
 
Flash said:
Might as well but its not necessary. If it was a bran new or rebuilt T/C then it would be highly recommended.

There is oil in the bottom of the T/C that will keep every thing lubed when you first start it.
Just make sure you have drained and refill the tranny pan before you start it.
I haven't done an auto in an XJ so i don't now for sure but i thing that dip stick tube has to be removed and if it's any thing like when you remove the pan to service it..............I't a PITA

Flash.
Click to expand...
Yeah the dipstick actually pulls in half, it already is as a matter of fact so it's not that bad. I think there is still a little bit of fluid in the bottom of the T/C, and I've had multiple people tell me it's not necessary to prime it, I just figured I would ask one more time straight out. Once I get it into place, I'm going to atleast pull the drain plug and replace the fluid that comes out that way. I assume the filter will still hold about a quart in, but I will probably do a pan drop/filter change after a while here. Thanks for the help.
-Collin
 
Colin,
Fill the TC as much as you can with fluid before you put it on. And, if you haven't already, replace the front input seal (that the TC snout fits inside)....it's only a $3 seal, but now's the time to do it while you have access to it, not later.

Use a couple drops of loctite on the flexplate bolts when reinstalling, too.

Have fun!
Jeff
 
Jeff in VA said:
Colin,
Fill the TC as much as you can with fluid before you put it on. And, if you haven't already, replace the front input seal (that the TC snout fits inside)....it's only a $3 seal, but now's the time to do it while you have access to it, not later.

Use a couple drops of loctite on the flexplate bolts when reinstalling, too.

Have fun!
Jeff
Click to expand...
Will do, it's all of $2.49 at O'Reilly's and I'm pretty sure that's where my old tranny puked it's fluid out at the day it decided to go. Is it a dry install seal or do I need to do something special with it?
 
smear a small amount of tranny fluid around the ID, to help prevent it from tearing when you initially fire it up and you'll be good to go.

Jeff
 
Jeff in VA said:
smear a small amount of tranny fluid around the ID, to help prevent it from tearing when you initially fire it up and you'll be good to go.

Jeff
Click to expand...
Thanks
 
Well it's in, I have it to the right fluid level and it goes through the gears (park to reverse and neutral to drive) a lot easier than my old 2 year ago rebuilt one did, I'm so glad it's finally done. Took me almost a week and a half because of school all day and working. I do have a problem though, I can't get it above idle speed without it bucking and backfiring very badly. I haven't really been able to test drive it because all it does is stumble and buck. Idling it is fine and smooth. With any throttle it runs like crap though. Can anyone think what I may have tampered with and/or not hooked up that would cause this? I used the Renix CPS and it is firmly seated against the bellhousing. It doesn't have to set in there a certain way does it? I had my 02 sensor out in the rain since it's in my exhaust but I can't imagine water would affect it that bad. And the CPS was sitting on my garage floor but it didn't come in direct contact with water either. I'm slightly confused here... Any ideas?
 
Hmmmm..... I know that my 89 has a ground strap that go's form the back head bolt,stud, to the fire wall..........could some one have moved that strap to the tranny bellhouisng bolt and it didn't get put back one?

Or maybe that ground strap broke or got pulled out of the fire wall.:dunno:

Flash.
 
Flash said:
Hmmmm..... I know that my 89 has a ground strap that go's form the back head bolt,stud, to the fire wall..........could some one have moved that strap to the tranny bellhouisng bolt and it didn't get put back one?

Or maybe that ground strap broke or got pulled out of the fire wall.:dunno:

Flash.
Click to expand...
I appreciate that suggestion. All my grounds are very tight and clean and that ground braid has been replaced with 2/0 gauge welding cable. I'm just trying to think what I might not have hooked back up that would be causing this.
 
I dont know if it matters, but are you running the same flywheel?

The CPS is located into position by the shoulder bolts...i had lost one when i swapped a motor, it wouldnt start.

When i swapped my first AW-4 i pinched the CPS harness between bellhousing and block, noticed it before attempting to start. If it's grounding out perhaps it could cause this symptom.
 
John B said:
I dont know if it matters, but are you running the same flywheel?

The CPS is located into position by the shoulder bolts...i had lost one when i swapped a motor, it wouldnt start.

When i swapped my first AW-4 i pinched the CPS harness between bellhousing and block, noticed it before attempting to start. If it's grounding out perhaps it could cause this symptom.
Click to expand...
Yeah I'm running the 1990 flywheel which is the original for my engine. I am also using the 1990 CPS since that is what my computer is looking for. The CPS is way tightened down and it is seated all the way against the bellhousing, no known issues there. It starts and idles just fine, it's just when I give it gas it bogs waaaay down. The harness is also way up out of the way on mine. I appreciate the suggestions though guys, keep 'em coming.
 
As mentioned in your other thread it sure sounds like a timing issue, but i'm suspect of the CPS still.

Was the CPS installed to the bellhousing before or after mating the trans to block? Could it have been damaged during install?
 
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