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Cracked AW4 body

I haven't been able to find anything on the subject here, I was chasing down what I thought was a leaky trans oil pan gasket but after I replaced it, still leaking. I thought it was the seal on the selector shaft that goes through the tranny because the leak was coming from behind the NSS switch so last night I removed the NSS and found a hair line crack about six inches long and about an inch behind the NSS shaft. The crack is in the actual body of the tranny.


My question for you guys is what is the suggested route to remedy this problem, should I try and put a bandaid on a bullet wound and JB weld it or is it done for good. I think the only reasonable explanation is an air bubble in the casting.


My main concern is that it compromised the structural integrity of the transmission body, I can't imagine how it happened because all it's seen are road miles. I bought it almost 2 years ago and shortly thereafter I got my current job and I work so much all I have time to do is work for money then wrench on the jeep for fun. I live in FL and the jeep belonged to an old man before me that bought is new. 98x xj AW4 140k, I've put alot of time and money in the jeep working on it and modifing it to its current state so that when I get done with this strech of working that I will be able to take it out and abuse it.


I have a local U-pull-it that has a bunch of jeeps and I know I could get one for cheap but I'm not sure of the usable life span of the AW4, 300k 500k?

I appriciate everyones input on the issue, I will try and take some pics tonight when I get home.

TIA-Kelvin
 
Well my '91 4.0/AW4 went 240k before I parked it.

Nothing wrong with it and the fluid was brown since I got it at 184k, and I beat the CRAP out of it.

I'd say it could have gone to 300k.
 
Casting leaks in trannys are fairly common, the recommended fix is JB weld. But if it's a stress fracture, JB isn't gonna hold. Second is. the aluminum is fairly porous and getting it clean enough for the JB weld to hold can be iffy.
 
My bet is the Jeep was in an accident. My Jeep was in an accident before I owned it. I know because the previous owner was my sister. The bell housing was cracked near the starter. I then broke it in about 5 pieces in Moab, 2200 miles from home.

That sucked....

I would change out the tranny. Any amount of band-aids are not going to stop the crack from getting bigger. I would be worried about a panic stop or evasive manuever putting forces on the cracked area, making it frag in more pieces unexpectedly.

A.
 
If you do go the JB route, try and grind the surface of the crack, so it can bite into the casting. Its a last ditch effort to fix a big problem (I know the feeling, I used a modified C-clamp on a chevy caprice th400 detent cable that I broke the mounting bolt on the trans, It worked until I nailed a 4 point buck at 75 mph :( ) Back to topic, I would try and find a good used Aw4 even if the JB method works because sooner or later you might need it.
 
You can find a low mileage Jeep AW-4 for less than $100. on www.car-part.com. I would swap in a different tranny and keep the leaker for spare parts.
 
Tim_MN said:
You can find a low mileage Jeep AW-4 for less than $100. on www.car-part.com. I would swap in a different tranny and keep the leaker for spare parts.


I was leaning twoards that route but I wanted to see if anyone else had repaired a problem like this first. I have bought parts from car-part.com before with good results so I think that's what I'll do. I just called on a 01' w 81k for $400, I think that I'm going to pick it up on monday and get a trans jack from Harbor Freight and start the battle.

Is there any special trick to removing the tranny cooler lines from the trans or is it pretty straight forward? I'm going to start reading my manual asap.

Thanks for all the input guys!!
 
Just did the same swap. The transmission lines are easy, squeeze the little plastic retainer clips and the lines slide right out of the trans.

The hardest part is the top bolts on the bell housing to the engine. Buy a E12 reverse torx socket. Pull the cross bar and lower the back of the transmission and use several long extensions to get to the top bolts.

I also made a set of guide bolts that work great. I took one the large lower bolts to the store and bought two long bolts the same size and thread. I cut the heads off of them and cut a slot for a screwdriver in the end. These can be threaded into the engine and used to guide the transmission back into place. I used the first to replace the clutch on my 96, but they work well on automatics too.
 
One of the local XJ guys got a 2000 aw-4 with 75,000 miles on it for $90. It came with a 1 year warranty also. $400 really seems to be too much.
 
Tim_MN said:
One of the local XJ guys got a 2000 aw-4 with 75,000 miles on it for $90. It came with a 1 year warranty also. $400 really seems to be too much.

I've been shopping around and $250-$400 is average price for a decent tranny with a warranty. I am in central FL, and I think that has something to do with. I've checked from Miami to Tallahassee and there all about the same. I appriciate you guys helping me out. thanks!:us:
 
Sorry to dredge this up from the grave, but I'm just curious if anyone has any more thoughts on this. Mine did the same thing (99 XJ), and it's getting swapped out this weekend, but I can't figure what the hell made it crack right there? And I haven't heard of it happening a lot, but mine is split the exact same way Pierce's is.
 
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