Front driveshaft keeps aspinning

[bdahlg]

1991 XJ Laredo 4L HO, NP231, AW4, 158,000 mi

Recently doing just a little wheelin, hill climbs and such, and realized that after one climb, i took it out of 4wd, part-time light diminishes, but i can tell my front driveshaft is still engaged (that sound that the front differential makes under the driver's side when brakes are depressed). Had my brother look at it when i put it in drive and sure enough it was spinning, obviously 4x4 lever was in 2H. I'm pretty sure (I've witnessed it) that it's not supposed to spin since it is engaged at the transfer case when lever is pulled. Don't know if it ever came out although the sound from the front differential did stop. I drove it 2 hours to Boston yesterday (don't know if this was the smartest move) but ran perfectly like it always does.
Anyways, it is vacuum actuated, could it be the shift linkage at the transfer case even though the actuator is not engaged (since this is where the part-time light switch is located at the actuator)? Also, is it dangerous to the Jeep driving on pavement with the front driveshaft spinning?
Any input would be appreciated, I just got her running absolutely perfect and plan to keep it that way

Thanks!!

[Cam7]

The Best way I that I use is to Jack up the Jeep and secure with Jack Stands that all 4 wheels are off the floor and make sure you use 4 Jack Stands. Then start the vechile and put into drive and see if all 4 wheels are turning. You will be able to tell if the front Diff is engaged and go from there for repairs. The 4wd shouldnt be driven on dry pavement for a long period of time.

[fredjacksonsan]

Keep in mind that on many models, the front differential is always engaged (no vacuum activation) so the driveshaft will always spin.

Cam7's idea, to jack up all 4 wheels, is a good one to verify the Tcase is disengaging.....if it is, no worries.

[2000izusu]

mine spins all the time but i have no vaccum disconnect.

[d0pod]

That vacuum system kinda sucks (no pun intended). Search google for "4x4 posi lock". Gets rid of the stock junk and operates on a cable setup instead.

Doesn't matter if it's spinning on road. As said most of them do...it's when it won't start spinning off road you run into problems.

[bdahlg]

No, I don't need the posi-lock. My vacuum is strong and the actuator engages and disengages quick and easy now that i replaced the vacuum line coming form the reservoir located in the front bumper. Since there is no serious issue with the front driveshaft spinning, im not really going to worry about it. Besides, i just checked it the ohter day and it wasn't spinning. I'm guessing it just taking longer for it to disengage for some reason. Thanks all for your help