I have a 99 grand cherokee. I think I may have busted an axle shaft, is there a way to tell without taking it all the way apart? I think I have heard something about jacking it up and spinning the wheels. What will it do if it is normal? Busted?

When I shift into 4wd I get a whining noise like the front driveshaft is turning, but I get no power to the front wheels. even when I am stopped the front drive shaft is spinning when in 4wd. Could that be something besides the axle shaft?

Thanks

It could be your hubs...



Most 4x4 have either manual or automatic locking hubs (so that when 4x4 is not engaged, the wheels will not spin the axles/diff/drive-shaft)....



I would assume the Jeep would have automatic hubs...



If the hubs fail to engage, you will have the above problem....



 

Jeeps have automatic hubs. So I'm taking from this that it is a front axle, and not a rear axle?

Jack it up, and see how the axels spin

A regular..non limited slip axel will spin one wheel forward..and the other the opposite direction.

A posi trac or limited slip....put the vehicle in nuetral..see if the wheels act like a normal dif..or might both try to spin the same direction.

If one wheel just free wheels...then maybe it busted something...axel or spider gears.

Correct. Front axle with automatic hubs.

Either your ring and pinion is shot or your hubs are trashed.  The front driveshaft should not spin without the tires moving.

Well, a month or two ago when I got the jeep I took it out to see if the 4wd worked. and it did, for a few minutes, on dry pavement I know I should not have done it, but I did. Something popped and this is the problem I have had ever since. I dont know what broke, but it has been working fine in 2wd. I am trying to get out today and find time to get under there and see what is going on with the 4wd.

You can run it on dry pavement just don't turn. I never understood this anyway. You can't really tell if its in 4 wheel drive or not on pavement anyway.
The way I do it is to get in some gravel and try and spin out alittle. That way I know its in 4 wheel drive and its working.