Trying to work out the kinks. Hit the switch, I hear the click and the 4HI button lights up. Put it in neutral and hit the button, the 4LO button lights up and the transfer case does go into low.

However, the front end is not receiving power. I got all 4 wheels off the ground. Put it in 4WD and the driveshaft is spinning and there is a grinding/buzzing/cards in bike spokes noise coming from under the front somewhere. Is there something that disconnects the front axleshafts that may not be engaging?

Help... It's becoming a money pit!

 

Sure there is something that disconnects the front axle. It is called the "vacuum actuator".

What are you driving?

 

Oops!

1996 Jimmy 4WD (obviously)

 

The vacuum actuator is under the battery. Engine vacuum runs to the vacuum switch on the transfer case which directs it to the actuator when in a 4wd mode. The actuator pulls on the cable to the front diff, connecting the passenger side axle.

So you need to check for vacuum at the actuator when in 4wd with the engine running. If you have vacuum, then the actuator may be bad or the cable may be froze up. If you do not have vacuum, you could have a bad vacuum line or a bad vacuum switch on the transfer case.

For more information, please use the search function with keywords from above. This problem has been covered a number of times.

 

I am finding it hard to test for vacuum when I have to remove the battery and tray to remove the vacuum module. How is one supposed to reattach the battery with the short cables to test it out?

I can pull on the cable end once I removed the vacuum module. I can feel it engage, but when I spin the tire by hand I still hear the ratcheting sound.

Is there anyway to permantly lock the front axle?

 

If you can hear it clicking, it is not fully engaging. The cable may get tight before it engages. Work some lubricant into the cable and then work the cable in and out until the travel improves. You may have to pull quite hard on it initially. You also may have to have someone else slightly rotate the passenger wheel while you pull on the cable to make it easier for the collar to lock into the splines on the passenger side outer axle half. Once it is aligned, you should be able to work it back and forth without moving the wheel again.

I test the actuator with a small hand vacuum pump (mine just happens to be a brake bleeder kit that works quite well for this). It should hold vacuum pressure once pumped down.

 

So here's the deal. I don't want to know the answer, but I am hoping I am wrong.

I pulled the skid plate down, and loosened the 3 bolts holding the shift cable in. I pulled the cover back as far as it would go...about an inch and got a little bit of gear lube dripping out. I then pulled on the whole assembly to engage it. The cable assembly only pops out about 1/2 inch and I can feel what feels like it trying to engage. If I turn the front tire backwards it will sometimes lock and I see the front driveshaft spin. However, if I turn the tire forward, it pulls the cable in and out as I hear it grinding on something inside the differential.

I don't know how to explain it better. As I am holding the cable it moves in and out at the same speed as the grinding gears.

My question. How far is this shift fork (cable) supposed to move?

What do I have to tear apart to get at the shift assembly?

Thanks!

 

It should move between a 1/2" and 3/4".

Have a look at THIS POST. It definitely sounds like the collar and/or splines on the outer axle shaft have some damage which is not allowing it to engage properly.

 

So here's the update.

Bit the bullet and pulled the passenger side axle tube and assembly off the front differential. It was not as bad as I had imagined it to be.

When I got it apart, all looked well until I tried to assemble it on the bench. The differential side slid right into the collar like it was supposed too. The right side axle side did not. It would just barely engage the teeth, and when I tried spinning the pieces in opposite directions.. You guessed it, the same noise and sensation I felt with it all installed.

So I laid the sleeve down as far as it would go on the damaged teeth and lightly tapped it with a hammer. It then after three taps, dropped down and fully engaged.

I played with it a while longer, and now have it reinstalled. Works good.

My only problem now, I damaged the lock spring taking the cable off the axle and I need a new one before I can button it all back up.

 

Thanks for the update!