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4 wheel drive not engaging what broke?

IDXJ

NAXJA Forum User
Location
Las Vegas
I was out on a trail yesterday. I was in 4 wheel drive obviously then heard a pop and no more 4 wheel drive. I checked all the usual axle shafts, u joints etc. I am going to dig into the front end this evening and wondered if anyone had some ideas. Heres whats working and not working. In 4 wheel drive my drive shaft is turning and my dash light is coming on but wheels are not getting power. I have a 1990 XJ with the 231. I drove the 125 miles home at 70 + with no problems at all.
 
Okay..just a couple suggestions.

First, take a vacuum pump and put vacuume on the shft fork on the RH side of the axle to engage the axle (If you have a disco axle that is).

Now, jack up the front wheels and spin the front DS manually..what happens? Do you feel any binding?

If everything seems cool there I'd be inclined to say T-Case, if nothing happens something diff-wise...pinion maybe?
 
oops forgot to add that I have vacuum going to the axle. That was the first thing I checked since it is the usual problem. My guess is it would not be a t case problem because the drive shaft turns when shifted into 4 wheel drive. Also I can spin the wheels freely when shifted into 4 wheel drives. My thought is maybe broken spider gears.
 
Also check to see that the shift fork on the axle hasn't broken. Just pull off the vacuum assembly cover on the axle and take a peek.
 
Yep had the same thing happen to me when I bought mine and the axle dsico shoft fork snapped. I bought a new one and apprently they new the design sucked because they redesigned it to make it beefier.
 
Your drive shaft will turn because the wheels turn it??? Not sure about this with a disconnect axle but my 97 did that.
 
Id suggest you put on jack stands and put it in 4wd(hi or low).You should be able to find out where it has lost connection.Do this with the engine running so you have vacumn but in park.
 
RCP Phx said:
Id suggest you put on jack stands and put it in 4wd(hi or low).You should be able to find out where it has lost connection.Do this with the engine running so you have vacumn but in park.
I did that. That is how I know the drive shaft is tuning but not the wheels. I am going to take a look at the shift fork tomorrow and see if that is it. Anyone know if I can pick up a shift fork at an auto parts store or is it a dealer thing.
 
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