12 Valve 2nd Gen Dodge Cummins 94-98 Discussion of 12 Valve 5.9 Liter Dodge Cummins Diesels with P7100 Injection Pumps

4x4 goes on and off

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Old 01-24-2016, 08:58 PM
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Default 4x4 goes on and off

Just got a new ring and pinion done in the front so everything is good to go for 4x4. But I'm having this problem sometimes where 4 wheel goes on and off. I don't have the vacuum set up on the axle I have the aftermarket pull in cab to get it into 4 wheel. I think this is where the problem lies, I'm wondering if maybe something needs to be tightened? The light for 4 wheel comes on but it isn't always in 4 wheel, it takes 3 or 4 pulls and release to get it in 4 wheel and then sometimes it feels like the fork like thing in the axles pops out or something. I have a friend that says his is just always locked and there is a steel plate over the opening. Since we don't have locking hubs I guess it wouldn't matter if it was done how his truck is
 
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Old 01-25-2016, 05:12 AM
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It wouldn't, I have my CAD pinned and have for nearly 100K of plowing snow, pulling overweight trailers, etc. It's easy to do, just cut a chunk of something tough like hydraulic hose, slice it the long way and snap it over the piston in the CAD so the fork can't disengage the collar. Depending on how rugged a material you use, you may or may not need a zip tie to hold it in place. You may notice a slight chucking in front with your wheels turned to the lock, depending you your tire size and how hard you drive it, but I don't even notice it in mine. I noticed no difference in NVH, fuel mileage or tire wear with this setup, only downside is that the 4WD light will always be on even if you're in 2WD. My boost gauge blocks that light though, so I don't notice that either.

Now, the problem you're describing may not be so simple to fix. The collar that slides back and forth to lock and unlock the right wheel from the center axle could be damaged, your passenger axle could be damaged, or what's more likely is that your center axle could be damaged. Pop the cad housing off the axle, slide the collar over and take a good look at the center axle splines to see if they're stripped. It's a common thing, a relatively cheap part and not too big a deal to change, so whether you do it yourself or pay someone to do it it shouldn't break the bank. Certainly no worse than a ring and pinion.
 
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Old 01-25-2016, 06:10 AM
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Another thing to check would be the plastic inserts that go in-between the collar and the fork. If the plastic inserts are not there, there will be a good amount of play between the collar and the fork making it hard to get and stay in 4x4.
 
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Old 01-25-2016, 12:13 PM
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Thanks guys I'll take a look this week. Everything inside the axle is new with no more then 2k on it except for anything to do with the cad, I haven't touched that.
 
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Old 01-25-2016, 05:18 PM
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Originally Posted by 94 12valve
Another thing to check would be the plastic inserts that go in-between the collar and the fork. If the plastic inserts are not there, there will be a good amount of play between the collar and the fork making it hard to get and stay in 4x4.


I don't have a plastic anything in there. WTF?
 
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Old 01-25-2016, 10:19 PM
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Did a little scrolling I guess I have a posi lock cable system. So when I remove the CAD cover to look back there I'm guessing oil will come out do I just dump more more back I through there when I'm done?
 
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Old 01-26-2016, 05:28 AM
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Originally Posted by JBearSVT


I don't have a plastic anything in there. WTF?
You should they clip on the fork and go in the collar

Originally Posted by Bloom12valve
Did a little scrolling I guess I have a posi lock cable system. So when I remove the CAD cover to look back there I'm guessing oil will come out do I just dump more more back I through there when I'm done?
Yes oil will come out. It would be best to dump oil into the differential cover through the fill hole.
 
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Old 01-26-2016, 04:21 PM
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I've had that thing off a million times, and never had more than a drip come out. Oil is supposed to dump out of it? WTF. I have it serviced every December before plow season, and check it every 5K when I service the truck. It's not like it's low, I would know. You're starting to freak me out.
 
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Old 01-26-2016, 06:44 PM
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everyone I have ever taken apart oil runs out. The oil seal is on the outer axle, there is a bearing on the inner shaft but still the CAD should have some oil in it.
 
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Old 01-27-2016, 04:58 PM
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It certainly has never been dry in there, but I've never been like "oh $#!+, I forgot stuff was gonna come out of here!"
 



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