Yeah, Mine leaked moisture and rusted up the inside of the tube. No vac. Remove the rubber connector that goes on the cad, Then switch between 2/4wd and feel the amount of vac at the connector with your finger(or a vac gague if you have one). You should have the same amount of vac on both.

 

Ok stop guessing or going off anecdotal experience. You need to TEST with a vacuum pump.

There's only two lines going to the CAD. Disconnect the rubber plug AT THE CAD and apply vacuum to either side while spinning the RF wheel. One side should lock relatively quickly (I realize this is subjective) and the other side should unlock relatively quickly. You must be spinning the wheel to allow the collar to slide reasonably. You can even just rock it forward/reverse.

The diaphragm should hold vacuum.

If this all seems OK, repeat at the TRANSFER CASE END of the hardlines. This will tell you if your metal hard lines are clogged or leaking.

Do this and report back.

You can also hook up your vac pump and use it as a gauge with engine running. How many inches of vacuum are you seeing at the CAD supply? Is it different at the xmember under the t-case where the hard lines begin? You can also check vacuum at the vac switch on top of the t-case, and while you're at it look at that big rubber connector -- I bet it's falling apart but maybe not

 

Also, 'tis the season for 4x4 problems! It's guaranteed every year like New Year's resolutioners at the gym in January. Buckle up everyone!