This is about an NP 231 in a '91 Dakota. I just put this xfer case in, and the front drive shaft isn't spinning. I've got all four wheels off the ground, and it feels like there's a little gentle rotational force on it when it's in gear, but not enough to drive the wheels.

First, are there hydraulics (like a clutch) in there that need fluid to operate, or is the fluid just a lubricant? I don't have any in there yet (see next question). Looking at the Haynes drawing, seems to me that it's just shafts and sprockets and chain, so if it's engaged it should work. If it needs the fluid in order to drive the front shaft, that's likely to be my problem.

Second, what do all y'all use to put fluid in these things? There's no way to pour from a jug into the fill plug hole, so is there some kind of little pump or something that does the job?

Thanks much.

Jonathan

 

I put atf+4 in mine.

it wont spin if its in 4hi or 4lo with the trans in park and youll feel some resistance with the trans in gear as you will also be moving the gears in the trans too.

I would not run it in 4wd without fluid in the case.

not sure about with it in 2wd but I dont trust it without fluid.

yes they make a pump that screws onto the bottle which makes it way easier. it cost like $6 at the autostore

 

What I meant is that with the xmission in gear and the xfer case in (either)
4, the front drive shaft is not spinning, so I've definitely got a problem here.
I've got all four wheels off the ground while doing this.

Understood, but is that what's keeping the front driveshaft from spinning?

 

A lack of fluid will not keep the front drive from engaging, but it will keep the transfer case from working for very long.

Is the engine running when you're doing this, or are you turning the wheels by hand? If turning by hand, is the opposite side front wheel turning?

If you are in 4WD and the engine is running, and the shaft isn't spinning, it sounds like you do, in fact, have a problem. Chain, maybe?

 

I think the op is trying to turn the driveshaft instead of the wheels.

try turning it with the trans in neutral instead of in gear.
or like tom said and have the engine running and see if it spins

 

Of course - I have no intention of running it dry, but I just wanted to see the front wheels turning and be able to get in and out of the garage under its own steam before filling it.

Yeah, the engine is running, it's in gear, and the rear wheels are turning. When I turn the front driveshaft by hand the front wheel turns, so I'm getting movement through the diff and the front axle disconnect is behaving properly. Interestingly, if I turn the front driveshaft backwards by hand, when I let go it'll rotate a fraction of a turn forwards (probably just until it takes up the front diff gear lash).

See, that's why I'm confused. Before I put it in I spun all the shafts by hand and moved the shifter between the positions to make sure it was behaving and that I was connecting it properly to the linkage (it's so eary to linkages on upside-down/backwards - I've done it on my Jeep too). So I really don't think the chain's toast.

 

Then it sounds to me like your linkage is out of adjustment or hooked up wrong and the case is not actually being shifted into 4WD.

 

Except that (as I said above) I checked it before I put it in to make sure I didn't get the linkage wrong, and loosened the adjusting bolt today to make sure it was falling into the detents properly. Also, the vacuum switch for the front axle disconnect is getting actuated properly, so that suggests the xfer case is being shifted properly.

 

Well, I can't imagine what could have happened to it between when you checked it out on the ground and when you installed it. That's just weird.

Almost sounds like an AWD transfer case. What happens if you put the parking brake on? The front wheels don't move then, right? (Not implying that you don't know the difference in cases, but I'm out of other ideas here.)

 

The "no frills" NP 231 is a very simple chain drive transfer case. If the front shaft isn't turning, the chances are that you have either a broken chain or (as has already been pointed out) a badly adjusted linkage. If you checked the shifting of this t-case before you installed it & it did shift properly, I'd put my money on the linkage either being loose, disconnected, or tightened in the wrong position.

There are lots of write-ups on these t-cases as well as exploded diagrams if you need them, but it should be easy to set up. Loosen the clamping bolts so that the linkage is still connected but free to slide in and out, then put the t-case into a gear by hand - if you can't tell which one it is, move the truck and see (if it moves very slowly, it's 4 lo). Now put the stick into that position, crawl back under and tighten the clamping bolts on the linkage and you should be OK. The early manual shift 4wd setups also had a front axle disconnect that essentially split one of the front axles (on my jeeps it's always been a vacuum disconnect, while on my GM pickup, it was electrical). If you have this type of axle, that's another area to look at if the 4wd isn't working. In the vacuum connections, there was usually a problem with one of the hoses or the vacuum actuator had rusted through. In the electrically driven systems, often the actuator is shot - a service manual of some sort should give you all the details on your particular truck (even a Haynes manual).