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AW-4 Tranny...toast?


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Edit: Forgive me as it is not a Comanche... but it is still a Jeep Cherokee, so I thought you guys might be able to help.

 

Well I'm usually a manual transmission guy myself, afer all both my Cherokee was and my Comanche is... but... recently my girlfriend picked up a 1997 2wd Jeep Cherokee (~150k mileage) It's been running well for the past month and a half (aside from slight oil consumption, it is still a Jeep after all :D ) Until about 3 or 4 days ago when it began making what sounded to be a rod knock, after doing my research, I learned that often the flex plate to torque converter bolts will loosen up and cause that exact noise... so I crawled under there, and sure enough they were a bit loose. The noise completely went away. We thought this was great.

 

But yesterday while driving down the highway it seemed to jump out of gear so my girlfriend pulled off, it died. She restarted it and it then drove to a parking lot where it began throwing codes, such as crankshaft position sensor and camshaft sensor. (We were able to limp it to an autozone nearby to get them read) From that point on it refused to engage in any gear both reverse as well as forward and seems to have a bit of vibration coming from the general transmission area. I tried resetting the computer in hopes that being a computer controlled tranny there might be the very off chance this would help, no dice. We got it towed to my shop.

 

So in conclusion, is it worth attempting anything... (common failures etc.) before I just scrap the tranny for the core and replace it with a rebuilt one. We really don't even have the cash to be dealing with this kind of problem at the moment so any help or ideas to a specific problem are GREATLY appreciated.

 

Thanks!

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The transmission would not throw CPS or TPS codes. Not sure, but I believe in '97 the TCU was still a separate box from the ECU, and the OBD-II diagnostic connector won't give you transmission codes. So if you are getting engine codes, then I would suggest before you start throwing transmissions at it -- find out what the problem is.

 

What did the "jumping out of gear" feel like? When the CPS goes bad, the engine may cut out and leave you essentially coasting. I think you probably just need a CPS, but others may have more/better ideas.

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:agree:

"Jumping" out of gear is not something an automatic is prone to do......slip, yes, lock-up problems, yes, but not jumping out of gear. I would look at the CPS first just to see if you hit it or something while tightening up things. Add to that your statement that the codes were CPS and/or cam sensor related........I assume you've checked the fluid, warm, engine running..... Don't know what tranny you have in the '97, but my AW4 is a pretty tough nut, fully capable of outliving the engine...

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@Eagle

I wish I could tell you... I wasn't in the vehicle when it "jumped out of gear" so it's difficult for me to assess exactly what it felt like. I wish I was driving when it happened. From what I can tell now it definitely feels like a tranny, atleast from experience... but if it happens to be anything else I'd definitely be much happier to have it be that. It almost seems to me that the Jeep may have been throwing codes b/c the computer became confused when the motor was no longer giving power to the wheels... but 'm not sure if the Jeep computer works like that at all... I've only messed with the C4 in my 67 Mustang (so of course no dummy lights/error codes), the rest of my cars have been standard.

 

I also had a CPS go bad in my Comanche... which was a manual, but it affected performance and gas mileage in that. How would that affect the auto transmission engagement... just out of sheer curiosity?

 

I'd love for it to be a CPS, because while it's not the most fun you can have it's a hell of a lot better than a tranny :rotf:

 

@Harper

Yes it's an AW-4... and I already checked connection on the CPS... unplugged it (of course won't start) plugged it back in and it started right up... so it is getting some sort of reading, that's not to say it's not faulty of course.

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SubSonic, I meant to check the CPS itself, not the connector. With older wiring, particularly where the CPS wiring is routed, with it's exposure to heat, and all the elements, etc. just movement of old wires can break or weaken them. Insulation gets frayed, cracks, hardens, etc. Maybe while it's idling, get underneath or reach down from above and wiggle the wire near the sensor itself, and see if that gets any results, keeping in mind that if nothing happens, that's not proof positive that the sensor itself isn't bad. These are the kind of analyses I generally do before throwing money at it. Do it carefully, bud.

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That's possible... I've been under there for the last 2 hours... it's got a weird vibration I've been tracking... one of the tranny to motor bolts had backed all the way out! :eek: I've begun replacing/checking the bolts and have actually gotten the thing to engage... although VERY unhappily and noisy at that but it would to nothing at all prior.... I'll check the flexplate as that is a good point...

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Yeah it seems the bolts were missing on both the left and the right side (tranny to motor bolts) I was able to recover one and put it back in before I discovered the other one missing on the left. I'd prefer not to pull the other one out again just to look at the bolt... so do any of you know what size bolt I need to pick up for the other side?

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No it's not cracked... which is good I guess... still has more vibration then I would like.... It seems that the passenger side tranny bolt was stripped so I used a smaller bolt and put a nut on the other side and locked it down... It's atleast running now... ;) However I found the passenger side reverse E12 Torx bolt just hanging out on the bellhousing.... any tips on getting that one back in? I remember the reverse Torx were a b*@$£ on the Comanche and that was with two people... not sure if I can even get it started by myself... it seems to like one person to hold it while the other is under the car w/ an extension and a wobbler... so any tips to doing it by oneself?

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Well got it all tightened up and back together and it ran perfectly. Picked up my girlfriend and brought her to her car. She got a mile and it started acting up again. It began slipping so badly it wouldn't even move again. We pushed the jeep back to the shop with my Comanche. I'm just about over it. Anything else I should try before I throw in the towel and core it out for a rebuilt one?

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Cherokees are a dime a dozen, even 4wd ones.......hint hint.

AW4s are nearly bullet proof, not very many failures for the numbers.

Myself, I'd forgo a rebuilt tranny, that kind of money could go a long way towards buying a whole nother XJ (4x4 maybe?) either a decent running one, or one for parts. Besides how much is a rebuilt tranny going to cost? Installed? BTW, some shops won't warranty a rebuilt tranny unless they install it. Most shadetree mechanics don't have the equipment to flush a tranny cooler and lines which is essential for a new/rebuilt tranny. Lastly, you could always put a used AW4 with TC in the GFs XJ, saving the rest of the conversion for a later date.

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What I'm considering doing is pulling the tranny myself then bringing it to a transmission rebuilding/supply house here locally that takes yours as a core in exchange for a freshly rebuilt one $400-500 probably. But like I said suggestions are great and if you think that finding a used one makes more sense than a rebuilt one I'll definitely keep my eyes open. For hers I'll keep it 2wd just to keep it simple for her car.

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i sent you a message i also add you are gonna have to pull it one way are another . the way it sounds I'm getting ready to do mine tommorow went tonight and bought a new trans jack at harbour freight cost $109 with 20percent offcoupon :banana:

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i sent you a message i also add you are gonna have to pull it one way are another . the way it sounds I'm getting ready to do mine tommorow went tonight and bought a new trans jack at harbour freight cost $109 with 20percent offcoupon :banana:

 

Yeah I'm always at harbor freight, cheap, cheap stuff for sure. Well let me know how it goes, I'm hoping to have time to tackle some of it monday or tomorrow if lucky... and it would be absolutely great to have insight as your doing yours as well... good luck man! I'll let you know when I get back into the Gf's.

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Any 91-97 tranny will fit any 91-97 XJ as far as I know except maybe the wiring harness connector (clip off, crimp/splice on, done.) Any 98-up will fit any 98-up. 98-up can be made to fit 97-down using custom electronics but not vice versa.

 

With that said, my suggestion would be to grab a 4wd AW-4 and a 231 (cheap and much more common than the 2wd AW-4 at least around here) and install it along with a 4wd rear driveshaft. Just put the transfer case in 2Hi and leave it that way. That way if you ever decide to do a 4wd conversion on it, the only things you have left are the dana 30, front driveshaft, and transfer case shift linkage and lever, i.e. the really easy parts. Should not cost you that much different from just a 2wd AW-4, either.

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