Krazeeun Posted April 23, 2006 Share Posted April 23, 2006 well low & behold...theres an MJ in my garage now too.... my room mate bought it from a second owner guy, who has never even tried to put it in 4wd in the 7 or 8 years that he's owned it... SWEET!! I thought..... but NO, NOT SWEET!! I can not for the life of me, make the thing engage in 4wd... I thought maybe it was because the disconnect wasn't working, so I decided to bypass it... I yanked out every 4wd vacuum part there was & blocked off the fittings on the tcase. Then I took off the actuator, I tried just blowing in the vacuum ports to make it shift, no go... so I tried to pull it over... no go... so then I soaked it in PB blaster and manhandled it with a big wrench.. finally it popped free, and it took more soaking in PB blaster & wiggling to make it work smoothly... with that being said, I pushed it over into the engaged position, and put vacuum caps on the ports, so it'll stay engaged, I then put it back together with the axle locked together I thought maybe the front driveshaft spinning would help it go into 4wd, but noo... I checked the Tcase fluid & topped it off, still nothing... I adjusted & readjusted the linkage.... nothing.. nada.. no 4wd When I pull up on the lever, it pulls up, and stays in the right place (4hi) (like my TJ does)... but the case doesnt send power to the front axle... and it will not go into (N) or (4lo) , it makes no noises, nice and quiet.... it just feels like I hit a mechanical block and won't go any further with that being said, this is a BONE STOCK 91 MJ SWB 4x4 with the NP231 case, that hasnt been engaged in 8+ years IS IT POSSIBLE... that I need to split the case and free some things up in there... since it hasnt been used in so long things are all locked up (like the front axle vacuum actuator motor...)???? HOW DO I MAKE 4x4 WORK AGAIN????? HELP!! Link to comment Share on other sites More sharing options...
CWLONGSHOT Posted April 23, 2006 Share Posted April 23, 2006 First off, you have some things mixed up, but I think you are on the right track as far as the linkages are binding. The vacuum on the front axle does two things. It puts vacuum to the diaphragm, which moves the fork and slides the collar to engage the inner and outer axles AND sends vacuum up to a switch on the pass side inner fender making the light on your dash light up. The Vacuum lines at the X-case do nothing in the shifting of the case. When the case is shifted it allows vacuum to run thru different lines and engage the front axle as previously described. In other words the vacuum has nothing to do with the Xcase's ability to shift into any gear. BUT, if it is faulty it can NOT send vacuum to the front axle in effect disabling the front axle. The drive shaft WILL still be spinning, but because of the OPEN front diff power is just sent to the pass side half shaft and NOT to either wheel. Thats why open diffs suck off road, the send power to the tire that is easiest to turn...got it? Now back to your problem....does the light come on the dash when you shift into 4wd and then back off when shifted out? This will not necessarily happen instantly, the collar must be moved back and fourth and sometimes the splines on the shafts done align up right away. A bit of very slow rolling helps. If so, it would appear the vacuum is working as required. Now back at the Xcase, dis assemble the shift linkage and shift tranny into neutral. (Be sure tires are safely chocked...don't need you getting squished!) You may need to get something to give you some more leverage. Say a deep socket and a 6-8" extension. You should be able to shift the Xcase thru its gears, 2wdHI-4wdHI-neutral-4wdLO. It should feel solid/firm as it clunks into every gear. I am expecting you find that the linkage is the culprit. I have had seen NUMEROUS XJ's with the linkages SO RUSTED they couldn't be freed enough to use again! If you Xcase will not shift in thei manor manually. Its likely it needs a tear down. If you fint the culprit IS the linkage you could try to remove and soalk it in PB Blaster but its likely you will just need to replace it. This is all assuming you have a 231 Xcase. Because it has a vac disco axle it came from the factory with a 231...but that dosen't mean its got one now! GOOD LUCK, CW Link to comment Share on other sites More sharing options...
Krazeeun Posted April 23, 2006 Author Share Posted April 23, 2006 I am completely aware of how the vacuum system works... and actually the vacuum doesnt have anything to do with the light on the dash, the light on the dash is turned on/off by the contact switch (the thing with wires) inside of the shift mechanism on the axle. The vacuum garbage is completely gone & plugged off, and the axle is temporarily locked into the engaged position since I manually slid it over, put vacuum caps (nipples?) over the fittings, and put it all back together. The front driveline is not causing the problem. When I put the Tcase into the 4HI position, it sounds & feels like it shifts, but I can still move the front driveshaft freely, and it physically will not go back into the neutral or 4lo position, it just won't go.... with that being said, I will try tearing apart the linkage and manually shifting it.... if not that I'm tearing into the Tcase next weekend... Link to comment Share on other sites More sharing options...
DirtyComanche Posted April 23, 2006 Share Posted April 23, 2006 I am completely aware of how the vacuum system works... and actually the vacuum doesnt have anything to do with the light on the dash, the light on the dash is turned on/off by the contact switch (the thing with wires) inside of the shift mechanism on the axle. On your TJ or XJ maybe. Not on a MJ. Unless they changed that in 91... And did you look at the shift linkage while you're there? You can take it off the tcase and wiggle the tcase into Lo. It's a b*@$£. Then yu can at least know if it's the linkage or case. Link to comment Share on other sites More sharing options...
Krazeeun Posted April 24, 2006 Author Share Posted April 24, 2006 I am completely aware of how the vacuum system works... and actually the vacuum doesnt have anything to do with the light on the dash, the light on the dash is turned on/off by the contact switch (the thing with wires) inside of the shift mechanism on the axle. On your TJ or XJ maybe. Not on a MJ. Unless they changed that in 91... And did you look at the shift linkage while you're there? You can take it off the tcase and wiggle the tcase into Lo. It's a @#$%. Then yu can at least know if it's the linkage or case. on the MJ in my garage, there is a contact switch (like a button), when the shift fork slides over to the engaged position it presses the switch, and the light turns on.... thank you for the input, I will post again after I try to manhandle the tcase into submission :twisted: Link to comment Share on other sites More sharing options...
CWLONGSHOT Posted April 24, 2006 Share Posted April 24, 2006 Good luck!! Sorry if I offended, didnt mean to suggest you didnt know what you where speaking of. But the way your first post read, it left me wondering. On the dozen or so XJ/YJ/MJ's I have worked on the vacuum is hooked to a little blue vacuum switch on the pass side inner fender. That is wired to the dash to show the 4x4 light to shine if and when there is vacuum to it. The Posi-lok has a contact switch inside as you describe. Let us know what you find!! CW Link to comment Share on other sites More sharing options...
Krazeeun Posted April 24, 2006 Author Share Posted April 24, 2006 I've collected another good tip from Cabz, over at the Florida Jeepers board.... he suggested pulling the plastic piece from around the tcase shifter and seeing if anything has gotted lodged in there and not allowing it to pull back all the way.... thats actually a damn good idea!! I will let everyone know how it works out when I get to it... thank you for the advice. :-D Link to comment Share on other sites More sharing options...
m0brando Posted April 24, 2006 Share Posted April 24, 2006 Just a note that a stock 91 MJ shouldn't have a factory disconnect axle. I know all YJ's had them but I believe in '90 they got rid of it for XJ's/MJ's. I know neither 92 that I have/had were disconnect. If your 91 has it could mean some modifications were done somewhere along the way (?). Brandon '92 MJ '97 XJ Numerous other J's Link to comment Share on other sites More sharing options...
Krazeeun Posted April 24, 2006 Author Share Posted April 24, 2006 this thing is stock as stock gets.... its got a d44 LSD w/D30 HP disco Link to comment Share on other sites More sharing options...
Eagle Posted April 24, 2006 Share Posted April 24, 2006 FWIW, the vacuum for the light works as CW said -- the switch should be on the passenger side of the firewall. The axle disconnect housing should have 3 vacuum tubes to it, but no electrical wires. As to the feeling that the t-case shifter moves back part way and hits a block: you are aware that there is a detent, right? It's a straight pull back to 4-HI, then you have to slide the handle to the right (offset) before pulling it the rest of the way for 4-Low. Link to comment Share on other sites More sharing options...
pingpong Posted April 24, 2006 Share Posted April 24, 2006 this thing is stock as stock gets.... its got a d44 LSD w/D30 HP disco 91's did not come with a d44 rear axle. they were only an option between 87-89. or this is what my research has found. also as pointed out by one of the other members, 90 should have been the last yr of the disco housing. Either some one has changed parts, or did something cause your jeep was not offeredc that way. Patrick Link to comment Share on other sites More sharing options...
Krazeeun Posted April 24, 2006 Author Share Posted April 24, 2006 Fact #1: this jeep is a 1991 Jeep MJ SWB Fact #2: it has a D30 HP disco with (2) vacuum fittings, and no sort of switch on any fender anywhere, it has only a contact switch with two wires inside of the housing that functions the dash light Fact #3: it has a D44 with LSD & 3.55 I will take pictures & prove my insanity!!!! :lol: I HIGHLY EXTREMELY DOUBT that this is ANYTHING BUT stock, it has stock shocks on it for christs sake.... BONE STOCK Link to comment Share on other sites More sharing options...
Pete M Posted April 24, 2006 Share Posted April 24, 2006 All the info I've seen says that the disco axle was discontinued in 94 and before that, all MJs/XJs that had the np-231/207 had the disco and all MJs/XJs with all-wheel drive had the non-disco (meaning a handful of 86 MJs got it). It's a very easy swap though, I plan on doing it to my 90 in a couple weeks (mostly to gain the 3.55 gears). Plenty of crazy things happened back then, so it's impossible to say what exact the factory was throwing on the trucks. Link to comment Share on other sites More sharing options...
Cooter Posted April 25, 2006 Share Posted April 25, 2006 My JY info is the same as what you have seen, peter. Krazeeun, where are you located? I got the ASAF part, but a little hazy on the rest... Link to comment Share on other sites More sharing options...
comancheon33 Posted April 25, 2006 Share Posted April 25, 2006 My 91 was bone stock when I got it. It had a 231 with a disconnect front axle. It also had the contact switch on the disconnect itself. No blue switch in mine on the passenger fenderwell. I am wondering about the danna 44 rear axle though. Link to comment Share on other sites More sharing options...
Pete M Posted April 25, 2006 Share Posted April 25, 2006 Dana 44s were offered right up to the end. Link to comment Share on other sites More sharing options...
Krazeeun Posted April 25, 2006 Author Share Posted April 25, 2006 SEE I'm not COMPLETELY INSANE!! :cheers: D44 rear with LSD & 3.55...... bone stock Link to comment Share on other sites More sharing options...
pingpong Posted April 25, 2006 Share Posted April 25, 2006 SEE I'm not COMPLETELY INSANE!! :cheers: Maybe not completely :nuts: and I was wrong again :banana: so its all good :cheers: Link to comment Share on other sites More sharing options...
m0brando Posted April 25, 2006 Share Posted April 25, 2006 But wait -- does this prove that I'm insane?!? Don't tell my wife if so! :) Well I know the 2 bone-stock '92 MJ's (current one was 1 owner) and the 93 XJ parts rig that I had/have all have a 231 and no disconnnect on the front axle. All are 5 speeds and the MJ's have a Dana 35 rear-end and the XJ an 8.25. So I guess it just proves that Chrysler wasn't any better than AMC about being consistent! Brandon '92 MJ '97 XJ Various other J's Link to comment Share on other sites More sharing options...
Krazeeun Posted April 25, 2006 Author Share Posted April 25, 2006 My JY info is the same as what you have seen, peter. Krazeeun, where are you located? I got the ASAF part, but a little hazy on the rest... Born & Raised in Haines City, FL Joined the USAF to see the world... :USAflag: Ended up at Hurlburt Field.... FL :mad: Link to comment Share on other sites More sharing options...
Pete M Posted April 25, 2006 Share Posted April 25, 2006 But wait -- does this prove that I'm insane?!? Don't tell my wife if so! :) Well I know the 2 bone-stock '92 MJ's (current one was 1 owner) and the 93 XJ parts rig that I had/have all have a 231 and no disconnnect on the front axle. All are 5 speeds and the MJ's have a Dana 35 rear-end and the XJ an 8.25. So I guess it just proves that Chrysler wasn't any better than AMC about being consistent! Brandon '92 MJ '97 XJ Various other J's Plenty of crazy things happened in the MJs life span. During the early years AMC was desparately trying to get products out the door. During the middle years there was the transition from AMC to Chrysler, both in manufacturing and then design. And then it was abruptly cancelled and who know what they were throwing at it in the last days. But then, the 92s are now 14 years old and a lot can happen in 14 years, especially when it comes to easily swapped parts. P.S. Are you typing your signature each time? Link to comment Share on other sites More sharing options...
Bounty Hunter Posted April 25, 2006 Share Posted April 25, 2006 EOD = Explosive Ordinance Disposal, right? The D30 disco will either have 3 vacuum lines, or 2 vacuum lines and 2 wires. Sounds like they switched over in at least '91 if that's what his jeep has. Not all D30 disco setups have the 4wd light switch on the fender or firewall. I recommend disconnecting the linkage arm from the transfer case and moving the sector shaft manually with a 3/8" wrench. If this doesn't shift it properly, I suggest taking the case apart and seeing what's going on. The 231 is very easy to rebuild, I'd do it for you if you were near St. Louis. Link to comment Share on other sites More sharing options...
DirtyComanche Posted April 26, 2006 Share Posted April 26, 2006 Yeah, just if you are going to rebuild it... Remove it from the vehicle first! (Hey, it was worth a shot) Link to comment Share on other sites More sharing options...
Krazeeun Posted April 26, 2006 Author Share Posted April 26, 2006 EOD = Explosive Ordinance Disposal, right? The D30 disco will either have 3 vacuum lines, or 2 vacuum lines and 2 wires. Sounds like they switched over in at least '91 if that's what his jeep has. Not all D30 disco setups have the 4wd light switch on the fender or firewall. I recommend disconnecting the linkage arm from the transfer case and moving the sector shaft manually with a 3/8" wrench. If this doesn't shift it properly, I suggest taking the case apart and seeing what's going on. The 231 is very easy to rebuild, I'd do it for you if you were near St. Louis. Explosive Ordnance (note the absense of the letter "I") Disposal baby!! :USAflag: This weekend if I get a chance (in the middle of an ORE :mad: ) I'm gonna try manually shifting & if no go... I'm splittin the case to see what I can find inside... not taking it out of the truck though, I did that with the NP242 in my XJ once.... never again :eek: Link to comment Share on other sites More sharing options...
CWLONGSHOT Posted May 11, 2006 Share Posted May 11, 2006 Hey man, How did this job go? What did you find out??? Imquiring minds want to know!!! CW Link to comment Share on other sites More sharing options...
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