Guys I need help...

About October I was putting the truck into 4 wheel and it made a clunk and decided to no longer function.
Since there was no real need for it and funds were slim I ignored it. Well come snow time I decide to take a look at it.
The piston in the CAD was bent, the fork had ground down because of this and had ground about 1/4" of splines off of the intermediate shaft.
I slowly rebuilt all of that. New Intermediate shaft, new axle seal, new cad.
Test drove tonight after Intermediate install and No 4x4.....SOB!!

Now i'm lost. What in the hell else could be wrong?

Transfer case works, when I put it in 4wheel the front drive shaft does spin.
Cad works of the truck, fork moves full travel.

but when i pull the 4wheel lever, no light, no four wheel, just the front axle spinning and rear tires spinning.

Any experts wanna help me out. I'm losing my hair over this!

Thanks in advanced.
Mike

 

Since it sounds like everything else is working smoothly then it must be a vacuum problem.
Vacuum should switch from one hose to the other depending on 4 or 2wd.
You could also have a vacuum leak somewhere else in the system that causes it not to have enough vacuum to move the CAD,

 

maybe the vacuum lines got switched around?

 

The 2 lines at the vacuum canister on the CAD, one always has vacuum when truck is running. Reverse them at the axle, and see if the pass axle is engaged.
The other issue could be the switch on the tcase, or a vacuum leak and no vacuum at all.
Do you have a vacuum gauge? easy to isolate and determine where the issue is.

 

Vacuum is fine. Cad works in both directions when using the vacuum.

 

Differential Experts, Heres my thought.
Is the intermediate shaft supposed to sync with the transfer case to engage 4 wheel drive? Im thinking maybe the shaft is not syncing, therefore the cad will not engage?

 

its just 2 gears meshing together. Pull the canister assembly off, is the collar lined up to the intermediate gear? can you slide it back and forth and engage the axle side?

 

Assuming that your front diff. is stock. Its an open differential. So the intermediate shaft spins backwards while in 2wd because the ring and pinion arent spinning and the spider gears are. When you put it in 4wd the transfer case starts spinning the front driveshaft and the front diff. spins normally. The intermediate shaft then starts spinning forward because the ring and pinion are spinning the same speed as the truck. Thats when the intermediate shaft and the right axle shaft start spinning the same speed. And thats when they sync up so the collar can lock the two shafts together.

Thats why when you put it in 4wd sometimes you have to move the truck a bit to get the 4wd light to come on.

 

Maybe the collar is backwards? Not sure if that matters or not.

 

What bent the piston in the first place? I would guess that you had a low vacuum situation that wasn't holding the collar firm and it was only engaging the intermediate shaft part way. That caused it to slip and make the clunk which also ground down the splines on the shaft.

Sounds like you've replaced everything else, so it either has to be not enough vacuum to move the CAD when together, or something internal in the axle.