deane.barker

I just bought a 1997 Grand Cherokee TSI with full-time 4WD. I've got two options: 4-Hi and 4-Lo.

When in 4-Hi, are the differentials supposed to be locked? I always thought they were unlocked in 4-Hi and only lock in 4-Lo.

But even in 4-Hi, when I turn sharply, the tires skid, which makes me think the diffs are locked.

Could the diffs be "stuck" or something? How can I unlock them?

JIMI B

I just bought a 97 for a winter car last week, and it does the same thing. Funny that my first result searching was this thread.

drakan1908

The diffs don't lock or unlock. You are always in 4wd. When you are in 4hi the transfercase acts like a diff and allows some slippage from front to rear. I think 4lo locks the front to the rear. I have the 242 (selectrac) that has fulltime 4wd that acts like yours but I also have parttime 4wd that locks the front to the rear and I have 4lo that also locks the front to the rear. It is possible the vc is going out of your transfercase. I have heard that to test this go to a big parking lot and make some figure 8's. You shouldn't feel any bind in the front end.

OverlandZJ

You both are experiencing a worn Viscous Coupler in the transfer case... NP249. This is very common of this model transfer case.

Do not repair it, it will happen again. What you want to do is locate a competent mechanic.. like a Jeep owner to swap in a NP231 or NP242. It's not a difficult job for someone familiar with this work. Where are y'all located.. we could possibly receommend someone/place.

91cavgt

I'm in the Dallas/Fort Worth area. Do you know anyone around here that can do that? It looks like the TC chain is stretched so to get by for now I am gonna remove the front driveshaft tomorrow. It looks like the NP231 and NP242 are more common than the NP249 as well so maybe they cost a little less? Any idea on what a shop might charge someone to do this swap?

zedpapa

don't remove the front shaft. that will destroy the viscous coupling and you wont be able to go anywhere. a viscous coupling is like a limited slip diff. it has a bunch a clutch plates in it. it slips when you turn to allow for different wheel speeds. what will happen if you remove the front shaft is the coupling will slip until it wears out and will then act like open diff.

zedpapa

91cavgt

Well, I believe the drive home stretched the TC chain and/or destroyed the viscous coupling. After I got home I found out that the Jeep I just bought had a 235/70/15 tire on the right front and 225/70/15 tires on all the other corners. The noise it was making was VERY bad so I wanted to see if taking the driveshaft off would allow me to drive the Jeep to and from work (only 8 miles one way) till I can find a replacement TC.