Stamey

Since I pulled the tranny on my 96, to put a new TC in, the 4x4 has not worked. The vacuum lines are connected correctly, and I just verified I have vacuum in the white plastic line that comes down from the engine, over the top of the tranny, to the valve on the transfer case. I do not have any noticable vacuum in the lines, black and red, that go down into metal lines on the cross member.
That valve on the transfer case rotates, well the plastic part with the vacuum ports on top. I can easily turn it. Is this supposed to happen? The bottom part of the valve is tight in the transfer case.
I am wondering if the valve is bad, but I am not sure about the turning, or what other checks I need to do to verify one way or the other.

Advice appreciated.

Thanks,
Chris

TxDiesel007

Forget that unreliable OEM system..

Posi lock it and forget about it... If your OEM system does not work, chances are that you have a leak in the vaccum lines somewhere. You might wanna check up by the fuel filter, and see to make sure all the lines are connected.. Secondly, check the T case, the plug above, the four way could be loose. Goin back for a sec, i use the small zip ties to shut all the hose ends to the actuall line that they plug to and ull be alright.. If the T case checks out, go ahead and inspect the vac lines, You could have oil in the ones that are below by the T case, if you do chances are that is causing them not to work.. If they are clean, go to ur CAD...

Pull the plug from the CAD housing, you should have vaccum on one line (with the truck running) and the other should not work, in 4wd the inverse should happen, and one pushes the collar to the axle to connect 4wd... NOw if you have vaccum and it still dont work, it might be in ur CAD.. take it off and inspect it, the shift fork might have worn out, or the grooves that the collar slides on might be bad...


More on the Posi Lock here.. and below..



https://www.dieseltruckresource.com/...ight=Posi+Lock
Rick

Stamey

At this point I don't have vacuum to the hoses the go to the crossmember, where metal lines carry it to the CAD. so I know my problem is before those lines, and I suspect the valve on the T-case. I have verified I have vacuum as far as the group of hoses that plug into the t-case. I have had a tough time getting that bunch of vacuum lines back on that valve, mainly because the rubber seems to have expanded and it doesn't fit well around those tabs that make it only plug in one way. Even so, I feel like I have gotten it on there enough to work, but the plastic ports part of the valve rotate independently of the metal part the goes into the t-case. I am trying to figure out if this could be my problem, and how to test it. Depending on how the valve operates, it may or may not be a problem.

Thanks,
Chris

wilderness

Triple check your plug on the t case. I just got mine back from the tranny shop and they plugged mine up wrong. I found out the hard way after I was shamefully stuck at deer camp. I'm not sure if the plug should turn on the tcase but I know the actuator turns on the vac lock on the front end. I fixed mine easily and have'nt had any probs since. That is a great set up that TX showed you though. Get a vacuum guage and pump and check every thing Make sure that the metal lines on the crossmember are hooked up the right way (I think the red one goes on the longer line if I remember correctly) Theese new part stores will give you a loaner vacuum guage for free. If the 4wheel drive worked before you pulled the tranny then someting is'nt hook back up right. Good luck!

TxDiesel007

You can buy the connecters at O Reily auto parts

I bought them in the help section. Yes the rubber expands, and makes them useless per say, heat and oil will screw them up too. But as Wilderness said, check that plug again and again, and my suggestion is make sure all ur vac lines are hooked up, if not then the 4wd will not function properly...

Seriously tho, just posi lock ur rigs and forget about 4wd issues.. That posi lock takes a severe beating on my truck at times and it holds awesome. Plus u have a 2 low for trailers.. what more do u need?

Rick

Birdman

The vacuum switch in the transfer are known to go bad.If the lines are swelled the switch is bad allowing the fluid in the transfer case to be sucked up into the vacuum lines.Trans fluid really makes the rubber hoses and the fitting swell